<?xml version="1.0" encoding="UTF-8"?>

<!--XBRL Document Created with the Workiva Platform-->
<!--Copyright 2026 Workiva-->
<!--r:019b130c-47fe-7eba-b77d-c2f010cc7326,g:77a7b8bd-5f13-4fec-9a28-e2e4907f8f66-->
<link:linkbase xmlns:link="http://www.xbrl.org/2003/linkbase" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xbrldt="http://xbrl.org/2005/xbrldt" xsi:schemaLocation="http://www.xbrl.org/2003/linkbase http://www.xbrl.org/2003/xbrl-linkbase-2003-12-31.xsd">
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/all" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#all"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#hypercube-dimension"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-default"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#dimension-domain"/>
  <link:arcroleRef arcroleURI="http://xbrl.org/int/dim/arcrole/domain-member" xlink:type="simple" xlink:href="http://www.xbrl.org/2005/xbrldt-2005.xsd#domain-member"/>
  <link:roleRef roleURI="http://www.vertiv.com/role/UNAUDITEDCONDENSEDCONSOLIDATEDSTATEMENTSOFEARNINGSLOSS" xlink:type="simple" xlink:href="vrt-20260331.xsd#UNAUDITEDCONDENSEDCONSOLIDATEDSTATEMENTSOFEARNINGSLOSS"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/UNAUDITEDCONDENSEDCONSOLIDATEDSTATEMENTSOFEARNINGSLOSS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019b130c-4943-74a2-bb0b-eed5c4cf5555" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019b130c-4943-7e03-aec1-b2a75d92c4d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-74a2-bb0b-eed5c4cf5555" xlink:to="loc_us-gaap_StatementTable_019b130c-4943-7e03-aec1-b2a75d92c4d1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019b130c-4943-7c6f-821e-357f31a5081b" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019b130c-4943-7e03-aec1-b2a75d92c4d1" xlink:to="loc_srt_ProductOrServiceAxis_019b130c-4943-7c6f-821e-357f31a5081b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019b130c-4943-7c6f-821e-357f31a5081b_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019b130c-4943-7c6f-821e-357f31a5081b" xlink:to="loc_srt_ProductsAndServicesDomain_019b130c-4943-7c6f-821e-357f31a5081b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019b130c-4943-7342-89fa-09f511b3c121" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019b130c-4943-7c6f-821e-357f31a5081b" xlink:to="loc_srt_ProductsAndServicesDomain_019b130c-4943-7342-89fa-09f511b3c121" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ProductMember_019b130c-4943-7847-baad-e650e81b79c5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ProductMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019b130c-4943-7342-89fa-09f511b3c121" xlink:to="loc_us-gaap_ProductMember_019b130c-4943-7847-baad-e650e81b79c5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ServiceMember_019b130c-4943-7f36-9893-ffc804c02830" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ServiceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019b130c-4943-7342-89fa-09f511b3c121" xlink:to="loc_us-gaap_ServiceMember_019b130c-4943-7f36-9893-ffc804c02830" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenuesAbstract_019b130c-4943-72d7-b3a3-1d1eda8ef4be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenuesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-74a2-bb0b-eed5c4cf5555" xlink:to="loc_us-gaap_RevenuesAbstract_019b130c-4943-72d7-b3a3-1d1eda8ef4be" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019b130c-4943-7b9e-b565-4bcdade9aa41" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenuesAbstract_019b130c-4943-72d7-b3a3-1d1eda8ef4be" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019b130c-4943-7b9e-b565-4bcdade9aa41" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_CostAndExpenseAbstract_019b130c-4943-7848-97ac-091068dc29bf" xlink:href="vrt-20260331.xsd#vrt_CostAndExpenseAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-74a2-bb0b-eed5c4cf5555" xlink:to="loc_vrt_CostAndExpenseAbstract_019b130c-4943-7848-97ac-091068dc29bf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostOfGoodsAndServicesSold_019b130c-4943-79d5-9b23-743536f7836c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostOfGoodsAndServicesSold"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vrt_CostAndExpenseAbstract_019b130c-4943-7848-97ac-091068dc29bf" xlink:to="loc_us-gaap_CostOfGoodsAndServicesSold_019b130c-4943-79d5-9b23-743536f7836c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingExpensesAbstract_019b130c-4943-7a16-b21f-d7da9fff1296" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingExpensesAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-74a2-bb0b-eed5c4cf5555" xlink:to="loc_us-gaap_OperatingExpensesAbstract_019b130c-4943-7a16-b21f-d7da9fff1296" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019b130c-4943-726f-bd38-90bb5d681ba0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019b130c-4943-7a16-b21f-d7da9fff1296" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019b130c-4943-726f-bd38-90bb5d681ba0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_AmortizationOfIntangibleAssetsExcludingCostsOfSales_019b130c-4943-71da-acdf-f5322e3214c9" xlink:href="vrt-20260331.xsd#vrt_AmortizationOfIntangibleAssetsExcludingCostsOfSales"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019b130c-4943-7a16-b21f-d7da9fff1296" xlink:to="loc_vrt_AmortizationOfIntangibleAssetsExcludingCostsOfSales_019b130c-4943-71da-acdf-f5322e3214c9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_019b130c-4943-7145-85ca-7890c80efadf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019b130c-4943-7a16-b21f-d7da9fff1296" xlink:to="loc_us-gaap_RestructuringCharges_019b130c-4943-7145-85ca-7890c80efadf" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_019b130c-4943-7a47-a1e7-f625318b3ee5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignCurrencyTransactionGainLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019b130c-4943-7a16-b21f-d7da9fff1296" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_019b130c-4943-7a47-a1e7-f625318b3ee5" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingIncomeExpenseNet_019b130c-4943-784a-89e2-c143db8c8a39" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherOperatingIncomeExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OperatingExpensesAbstract_019b130c-4943-7a16-b21f-d7da9fff1296" xlink:to="loc_us-gaap_OtherOperatingIncomeExpenseNet_019b130c-4943-784a-89e2-c143db8c8a39" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019b130c-4943-7c1c-b944-559013e218bd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-74a2-bb0b-eed5c4cf5555" xlink:to="loc_us-gaap_OperatingIncomeLoss_019b130c-4943-7c1c-b944-559013e218bd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestExpense_019b130c-4943-7cab-9af6-e6c2b9f78d75" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-74a2-bb0b-eed5c4cf5555" xlink:to="loc_us-gaap_InterestExpense_019b130c-4943-7cab-9af6-e6c2b9f78d75" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019b130c-4943-7809-88a1-59bf270a0e36" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-74a2-bb0b-eed5c4cf5555" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019b130c-4943-7809-88a1-59bf270a0e36" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019b130c-4943-720f-8ff9-fcc455fc4cbc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-74a2-bb0b-eed5c4cf5555" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019b130c-4943-720f-8ff9-fcc455fc4cbc" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeTaxExpenseBenefit_019b130c-4943-7cec-86b5-1dfef4aeeb0f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeTaxExpenseBenefit"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-74a2-bb0b-eed5c4cf5555" xlink:to="loc_us-gaap_IncomeTaxExpenseBenefit_019b130c-4943-7cec-86b5-1dfef4aeeb0f" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019b130c-4943-7a73-a33f-1223157aeffe" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-74a2-bb0b-eed5c4cf5555" xlink:to="loc_us-gaap_NetIncomeLoss_019b130c-4943-7a73-a33f-1223157aeffe" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareAbstract_019b130c-4943-7c25-aba4-519427b47915" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-74a2-bb0b-eed5c4cf5555" xlink:to="loc_us-gaap_EarningsPerShareAbstract_019b130c-4943-7c25-aba4-519427b47915" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareBasic_019b130c-4943-728a-98e3-421975ce2888" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_019b130c-4943-7c25-aba4-519427b47915" xlink:to="loc_us-gaap_EarningsPerShareBasic_019b130c-4943-728a-98e3-421975ce2888" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EarningsPerShareDiluted_019b130c-4943-783d-aa3a-5a5ec4688fe9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EarningsPerShareDiluted"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EarningsPerShareAbstract_019b130c-4943-7c25-aba4-519427b47915" xlink:to="loc_us-gaap_EarningsPerShareDiluted_019b130c-4943-783d-aa3a-5a5ec4688fe9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_WeightedAverageSharesOutstandingBasicAndDilutedAbstract_019b130c-4943-7dbf-87d6-e05625692ed1" xlink:href="vrt-20260331.xsd#vrt_WeightedAverageSharesOutstandingBasicAndDilutedAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-74a2-bb0b-eed5c4cf5555" xlink:to="loc_vrt_WeightedAverageSharesOutstandingBasicAndDilutedAbstract_019b130c-4943-7dbf-87d6-e05625692ed1" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019b130c-4943-7cb0-9677-b5a2dcd30311" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfSharesOutstandingBasic"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vrt_WeightedAverageSharesOutstandingBasicAndDilutedAbstract_019b130c-4943-7dbf-87d6-e05625692ed1" xlink:to="loc_us-gaap_WeightedAverageNumberOfSharesOutstandingBasic_019b130c-4943-7cb0-9677-b5a2dcd30311" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019b130c-4943-710c-8a1b-9db89347be3d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vrt_WeightedAverageSharesOutstandingBasicAndDilutedAbstract_019b130c-4943-7dbf-87d6-e05625692ed1" xlink:to="loc_us-gaap_WeightedAverageNumberOfDilutedSharesOutstanding_019b130c-4943-710c-8a1b-9db89347be3d" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/UNAUDITEDCONDENSEDCONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMELOSS" xlink:type="simple" xlink:href="vrt-20260331.xsd#UNAUDITEDCONDENSEDCONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMELOSS"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/UNAUDITEDCONDENSEDCONSOLIDATEDSTATEMENTSOFCOMPREHENSIVEINCOMELOSS" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019b130c-4943-7582-a849-086e31dce236" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019b130c-4943-719c-9184-fba44550d89a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-7582-a849-086e31dce236" xlink:to="loc_us-gaap_StatementTable_019b130c-4943-719c-9184-fba44550d89a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019b130c-4943-7f11-9766-287a8b857eab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019b130c-4943-719c-9184-fba44550d89a" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019b130c-4943-7f11-9766-287a8b857eab" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019b130c-4943-7f11-9766-287a8b857eab_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019b130c-4943-7f11-9766-287a8b857eab" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019b130c-4943-7f11-9766-287a8b857eab_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019b130c-4943-72f7-8b25-e8b098b3ed80" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019b130c-4943-7f11-9766-287a8b857eab" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019b130c-4943-72f7-8b25-e8b098b3ed80" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_019b130c-4943-7734-b664-6591c4aca066" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019b130c-4943-72f7-8b25-e8b098b3ed80" xlink:to="loc_us-gaap_InterestRateSwapMember_019b130c-4943-7734-b664-6591c4aca066" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_019b130c-4943-7dac-bca1-37bce3a3aece" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019b130c-4943-72f7-8b25-e8b098b3ed80" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_019b130c-4943-7dac-bca1-37bce3a3aece" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019b130c-4943-789d-b052-d464735ab4bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-7582-a849-086e31dce236" xlink:to="loc_us-gaap_NetIncomeLoss_019b130c-4943-789d-b052-d464735ab4bf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParentAbstract_019b130c-4943-76b7-8f32-be12ff26e998" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParentAbstract"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-7582-a849-086e31dce236" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParentAbstract_019b130c-4943-76b7-8f32-be12ff26e998" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_019b130c-4943-7308-8205-fb8651719757" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParentAbstract_019b130c-4943-76b7-8f32-be12ff26e998" xlink:to="loc_us-gaap_OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationAdjustmentNetOfTaxPortionAttributableToParent_019b130c-4943-7308-8205-fb8651719757" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent_019b130c-4943-7c48-b5cc-8165f53480e7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParentAbstract_019b130c-4943-76b7-8f32-be12ff26e998" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossAfterReclassificationAndTaxParent_019b130c-4943-7c48-b5cc-8165f53480e7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent_019b130c-4943-7c16-a6de-df804ab48d55" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParentAbstract_019b130c-4943-76b7-8f32-be12ff26e998" xlink:to="loc_us-gaap_OtherComprehensiveIncomeDefinedBenefitPlansAdjustmentNetOfTaxPortionAttributableToParent_019b130c-4943-7c16-a6de-df804ab48d55" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019b130c-4943-7109-9459-33ee8c58f9b7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParentAbstract_019b130c-4943-76b7-8f32-be12ff26e998" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019b130c-4943-7109-9459-33ee8c58f9b7" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ComprehensiveIncomeNetOfTax_019b130c-4943-79b1-a608-0bda57d23b05" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ComprehensiveIncomeNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-7582-a849-086e31dce236" xlink:to="loc_us-gaap_ComprehensiveIncomeNetOfTax_019b130c-4943-79b1-a608-0bda57d23b05" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/UNAUDITEDCONDENSEDCONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITYDEFICIT" xlink:type="simple" xlink:href="vrt-20260331.xsd#UNAUDITEDCONDENSEDCONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITYDEFICIT"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/UNAUDITEDCONDENSEDCONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITYDEFICIT" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019b130c-4943-767d-ba40-fea58f14130b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019b130c-4943-7d8f-b45c-0c793d0929a8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-767d-ba40-fea58f14130b" xlink:to="loc_us-gaap_StatementTable_019b130c-4943-7d8f-b45c-0c793d0929a8" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019b130c-4943-71b0-8b36-7bfae161fa57" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019b130c-4943-7d8f-b45c-0c793d0929a8" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019b130c-4943-71b0-8b36-7bfae161fa57" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019b130c-4943-71b0-8b36-7bfae161fa57_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019b130c-4943-71b0-8b36-7bfae161fa57" xlink:to="loc_us-gaap_EquityComponentDomain_019b130c-4943-71b0-8b36-7bfae161fa57_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019b130c-4943-7414-aaea-bb505c642292" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019b130c-4943-71b0-8b36-7bfae161fa57" xlink:to="loc_us-gaap_EquityComponentDomain_019b130c-4943-7414-aaea-bb505c642292" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockMember_019b130c-4943-7086-a793-c3d8bea0a4bf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019b130c-4943-7414-aaea-bb505c642292" xlink:to="loc_us-gaap_CommonStockMember_019b130c-4943-7086-a793-c3d8bea0a4bf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019b130c-4943-7fff-9ac3-c7d510e9f8ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019b130c-4943-7414-aaea-bb505c642292" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019b130c-4943-7fff-9ac3-c7d510e9f8ff" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RetainedEarningsMember_019b130c-4943-74a5-b3ce-c96df999ff45" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RetainedEarningsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019b130c-4943-7414-aaea-bb505c642292" xlink:to="loc_us-gaap_RetainedEarningsMember_019b130c-4943-74a5-b3ce-c96df999ff45" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019b130c-4943-7275-9fe7-8893dff679e1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019b130c-4943-7414-aaea-bb505c642292" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019b130c-4943-7275-9fe7-8893dff679e1" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019b130c-4943-7276-9b63-4b9e240c0d17" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncreaseDecreaseInStockholdersEquityRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-767d-ba40-fea58f14130b" xlink:to="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019b130c-4943-7276-9b63-4b9e240c0d17" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019b130c-4943-7ac6-a450-f7512a125326" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019b130c-4943-7276-9b63-4b9e240c0d17" xlink:to="loc_us-gaap_CommonStockSharesOutstanding_019b130c-4943-7ac6-a450-f7512a125326" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019b130c-4943-73f0-87ee-a7d54619922f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019b130c-4943-7276-9b63-4b9e240c0d17" xlink:to="loc_us-gaap_StockholdersEquity_019b130c-4943-73f0-87ee-a7d54619922f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetIncomeLoss_019b130c-4943-78f1-9a3c-a46228c45852" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019b130c-4943-7276-9b63-4b9e240c0d17" xlink:to="loc_us-gaap_NetIncomeLoss_019b130c-4943-78f1-9a3c-a46228c45852" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_019b130c-4943-7fa5-8954-be97a09a06dd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019b130c-4943-7276-9b63-4b9e240c0d17" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised_019b130c-4943-7fa5-8954-be97a09a06dd" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_019b130c-4943-766f-b358-6df5b10ab273" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019b130c-4943-7276-9b63-4b9e240c0d17" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueStockOptionsExercised_019b130c-4943-766f-b358-6df5b10ab273" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019b130c-4943-79f6-8e01-b71aa73a8d97" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019b130c-4943-7276-9b63-4b9e240c0d17" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesShareBasedCompensation_019b130c-4943-79f6-8e01-b71aa73a8d97" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_019b130c-4943-76fe-9b54-d7e73164f7fd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019b130c-4943-7276-9b63-4b9e240c0d17" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueShareBasedCompensation_019b130c-4943-76fe-9b54-d7e73164f7fd" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeBenefitPlan_019b130c-4943-75ce-a087-f62ee0edc8c2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodSharesEmployeeBenefitPlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019b130c-4943-7276-9b63-4b9e240c0d17" xlink:to="loc_us-gaap_StockIssuedDuringPeriodSharesEmployeeBenefitPlan_019b130c-4943-75ce-a087-f62ee0edc8c2" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeBenefitPlan_019b130c-4943-7a2e-a818-3317e7bebfd8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockIssuedDuringPeriodValueEmployeeBenefitPlan"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019b130c-4943-7276-9b63-4b9e240c0d17" xlink:to="loc_us-gaap_StockIssuedDuringPeriodValueEmployeeBenefitPlan_019b130c-4943-7a2e-a818-3317e7bebfd8" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Dividends_019b130c-4943-7b32-9894-a682940407d7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Dividends"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019b130c-4943-7276-9b63-4b9e240c0d17" xlink:to="loc_us-gaap_Dividends_019b130c-4943-7b32-9894-a682940407d7" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019b130c-4943-7de1-9cbe-44c1aa3757f4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_IncreaseDecreaseInStockholdersEquityRollForward_019b130c-4943-7276-9b63-4b9e240c0d17" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTax_019b130c-4943-7de1-9cbe-44c1aa3757f4" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CommonStockSharesOutstanding_019b130c-4943-71d7-a5b4-a8d5dafe6f1c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CommonStockSharesOutstanding"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019b130c-4943-7229-9dc3-3ecbee6000a0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/UNAUDITEDCONDENSEDCONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITYDEFICITParenthetical" xlink:type="simple" xlink:href="vrt-20260331.xsd#UNAUDITEDCONDENSEDCONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITYDEFICITParenthetical"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/UNAUDITEDCONDENSEDCONSOLIDATEDSTATEMENTSOFSHAREHOLDERSEQUITYDEFICITParenthetical" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementLineItems_019b130c-4943-795f-a521-8ad86c682d79" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementTable_019b130c-4943-7111-92ef-f262d01a6ad2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-795f-a521-8ad86c682d79" xlink:to="loc_us-gaap_StatementTable_019b130c-4943-7111-92ef-f262d01a6ad2" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019b130c-4943-729b-8449-52fe0f59fbe7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_StatementTable_019b130c-4943-7111-92ef-f262d01a6ad2" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019b130c-4943-729b-8449-52fe0f59fbe7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019b130c-4943-729b-8449-52fe0f59fbe7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019b130c-4943-729b-8449-52fe0f59fbe7" xlink:to="loc_us-gaap_EquityComponentDomain_019b130c-4943-729b-8449-52fe0f59fbe7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019b130c-4943-79f8-897f-3ea2a19aa9b5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019b130c-4943-729b-8449-52fe0f59fbe7" xlink:to="loc_us-gaap_EquityComponentDomain_019b130c-4943-79f8-897f-3ea2a19aa9b5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdditionalPaidInCapitalMember_019b130c-4943-719f-aded-59a4d6841789" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdditionalPaidInCapitalMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019b130c-4943-79f8-897f-3ea2a19aa9b5" xlink:to="loc_us-gaap_AdditionalPaidInCapitalMember_019b130c-4943-719f-aded-59a4d6841789" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_019b130c-4943-7817-9d75-c6b624e041b1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-795f-a521-8ad86c682d79" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedNumberOfShares_019b130c-4943-7817-9d75-c6b624e041b1" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_019b130c-4943-7433-aa57-554d35fdf9ca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-795f-a521-8ad86c682d79" xlink:to="loc_us-gaap_SharesPaidForTaxWithholdingForShareBasedCompensation_019b130c-4943-7433-aa57-554d35fdf9ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_019b130c-4943-763a-a305-94b19b1147ab" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-795f-a521-8ad86c682d79" xlink:to="loc_us-gaap_AdjustmentsRelatedToTaxWithholdingForShareBasedCompensation_019b130c-4943-763a-a305-94b19b1147ab" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_019b130c-4943-75d8-9acb-dd0287a0ece4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_StatementLineItems_019b130c-4943-795f-a521-8ad86c682d79" xlink:to="loc_us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedInPeriodFairValue1_019b130c-4943-75d8-9acb-dd0287a0ece4" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/ACQUISITIONSNarrativeDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#ACQUISITIONSNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/ACQUISITIONSNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7c3f-bea5-659a93c75053" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019cd0fe-e733-7608-b369-8f301eb8005b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7c3f-bea5-659a93c75053" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019cd0fe-e733-7608-b369-8f301eb8005b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019cd0fe-e733-72ae-a3e5-b86c36500a52" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019cd0fe-e733-7608-b369-8f301eb8005b" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019cd0fe-e733-72ae-a3e5-b86c36500a52" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd0fe-e733-72ae-a3e5-b86c36500a52_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019cd0fe-e733-72ae-a3e5-b86c36500a52" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd0fe-e733-72ae-a3e5-b86c36500a52_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd0fe-e733-75c8-97e9-7cb7d07c74b1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019cd0fe-e733-72ae-a3e5-b86c36500a52" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd0fe-e733-75c8-97e9-7cb7d07c74b1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_PurgeRiteIntermediateLLCMember_019cd0fe-e733-71f0-bcff-02f29a464800" xlink:href="vrt-20260331.xsd#vrt_PurgeRiteIntermediateLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd0fe-e733-75c8-97e9-7cb7d07c74b1" xlink:to="loc_vrt_PurgeRiteIntermediateLLCMember_019cd0fe-e733-71f0-bcff-02f29a464800" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_GreatLakesMember_019cd0fe-e733-7f0f-ad68-02cfc2fd567f" xlink:href="vrt-20260331.xsd#vrt_GreatLakesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd0fe-e733-75c8-97e9-7cb7d07c74b1" xlink:to="loc_vrt_GreatLakesMember_019cd0fe-e733-7f0f-ad68-02cfc2fd567f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019cd0fe-e733-76c7-a308-6811ff529cef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019cd0fe-e733-7608-b369-8f301eb8005b" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019cd0fe-e733-76c7-a308-6811ff529cef" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd0fe-e733-76c7-a308-6811ff529cef_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019cd0fe-e733-76c7-a308-6811ff529cef" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd0fe-e733-76c7-a308-6811ff529cef_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd0fe-e733-709f-a641-b49857eb37d1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019cd0fe-e733-76c7-a308-6811ff529cef" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd0fe-e733-709f-a641-b49857eb37d1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_019cd0fe-e733-7d2c-8885-08a2f5feb909" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd0fe-e733-709f-a641-b49857eb37d1" xlink:to="loc_us-gaap_CustomerRelationshipsMember_019cd0fe-e733-7d2c-8885-08a2f5feb909" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeAxis_019cd0fe-e733-7b61-bc80-d00635f7a9d2" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019cd0fe-e733-7608-b369-8f301eb8005b" xlink:to="loc_srt_RangeAxis_019cd0fe-e733-7b61-bc80-d00635f7a9d2" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cd0fe-e733-7b61-bc80-d00635f7a9d2_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_RangeAxis_019cd0fe-e733-7b61-bc80-d00635f7a9d2" xlink:to="loc_srt_RangeMember_019cd0fe-e733-7b61-bc80-d00635f7a9d2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_RangeMember_019cd0fe-e733-76cf-a285-281197326467" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_RangeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_RangeAxis_019cd0fe-e733-7b61-bc80-d00635f7a9d2" xlink:to="loc_srt_RangeMember_019cd0fe-e733-76cf-a285-281197326467" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MinimumMember_019cd0fe-e733-7f97-b8d2-8979167b94e0" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MinimumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cd0fe-e733-76cf-a285-281197326467" xlink:to="loc_srt_MinimumMember_019cd0fe-e733-7f97-b8d2-8979167b94e0" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_MaximumMember_019cd0fe-e733-7e8b-805a-3642924b3f8c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_MaximumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_RangeMember_019cd0fe-e733-76cf-a285-281197326467" xlink:to="loc_srt_MaximumMember_019cd0fe-e733-7e8b-805a-3642924b3f8c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019d959d-316a-7050-b932-ca369aa88034" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019cd0fe-e733-7608-b369-8f301eb8005b" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019d959d-316a-7050-b932-ca369aa88034" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019d959d-316a-7050-b932-ca369aa88034_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019d959d-316a-7050-b932-ca369aa88034" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019d959d-316a-7050-b932-ca369aa88034_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019d959d-316a-77de-8b21-83593456664f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019d959d-316a-7050-b932-ca369aa88034" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019d959d-316a-77de-8b21-83593456664f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019d959d-316a-7535-93aa-b67e653596d2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019d959d-316a-77de-8b21-83593456664f" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019d959d-316a-7535-93aa-b67e653596d2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferred1_019cd0fe-e733-71f8-8e53-6515cf37d7ff" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationConsiderationTransferred1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7c3f-bea5-659a93c75053" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferred1_019cd0fe-e733-71f8-8e53-6515cf37d7ff" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAcquiredFromAcquisition_019cd0fe-e733-7709-ab0b-ed99dc584018" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAcquiredFromAcquisition"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7c3f-bea5-659a93c75053" xlink:to="loc_us-gaap_CashAcquiredFromAcquisition_019cd0fe-e733-7709-ab0b-ed99dc584018" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesGross_019cd0fe-e733-723a-90d6-2ccc7e99c281" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireBusinessesGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7c3f-bea5-659a93c75053" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesGross_019cd0fe-e733-723a-90d6-2ccc7e99c281" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019cd0fe-e733-7f0f-b4f6-b6358e9c6048" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7c3f-bea5-659a93c75053" xlink:to="loc_us-gaap_PaymentsToAcquireBusinessesNetOfCashAcquired_019cd0fe-e733-7f0f-b4f6-b6358e9c6048" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_BusinessCombinationConsiderationTransferredContingentConsideration_019cd0fe-e733-7b4d-8004-4efb7a1a14df" xlink:href="vrt-20260331.xsd#vrt_BusinessCombinationConsiderationTransferredContingentConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7c3f-bea5-659a93c75053" xlink:to="loc_vrt_BusinessCombinationConsiderationTransferredContingentConsideration_019cd0fe-e733-7b4d-8004-4efb7a1a14df" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationConsiderationTransferredOther1_019cd0fe-e733-7c34-b3ba-c862de918520" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationConsiderationTransferredOther1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7c3f-bea5-659a93c75053" xlink:to="loc_us-gaap_BusinessCombinationConsiderationTransferredOther1_019cd0fe-e733-7c34-b3ba-c862de918520" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_BusinessCombinationAdditionalCashConsideration_019cd0fe-e733-7de5-a395-933e5de894fe" xlink:href="vrt-20260331.xsd#vrt_BusinessCombinationAdditionalCashConsideration"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7c3f-bea5-659a93c75053" xlink:to="loc_vrt_BusinessCombinationAdditionalCashConsideration_019cd0fe-e733-7de5-a395-933e5de894fe" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019d959d-316a-7f02-be6a-3f9b7e33bc95" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7c3f-bea5-659a93c75053" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019d959d-316a-7f02-be6a-3f9b7e33bc95" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingIncomeExpenseNet_019d959d-316a-71d5-8417-c497e7530bc4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherOperatingIncomeExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7c3f-bea5-659a93c75053" xlink:to="loc_us-gaap_OtherOperatingIncomeExpenseNet_019d959d-316a-71d5-8417-c497e7530bc4" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_019cd0fe-e733-7d7f-8d4e-5580f0c1aa7a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7c3f-bea5-659a93c75053" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_019cd0fe-e733-7d7f-8d4e-5580f0c1aa7a" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_019cd0fe-e733-7ea7-87e7-3dfb19574fbf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7c3f-bea5-659a93c75053" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_019cd0fe-e733-7ea7-87e7-3dfb19574fbf" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_BusinessCombinationRecognizedAssetAcquiredAccountsReceivableAndInventory_019cd0fe-e733-73b0-98f2-c9b74765fbab" xlink:href="vrt-20260331.xsd#vrt_BusinessCombinationRecognizedAssetAcquiredAccountsReceivableAndInventory"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7c3f-bea5-659a93c75053" xlink:to="loc_vrt_BusinessCombinationRecognizedAssetAcquiredAccountsReceivableAndInventory_019cd0fe-e733-73b0-98f2-c9b74765fbab" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_019cd0fe-e733-7dbf-8b3c-c4237c224c23" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7c3f-bea5-659a93c75053" xlink:to="loc_us-gaap_BusinessAcquisitionPurchasePriceAllocationGoodwillExpectedTaxDeductibleAmount_019cd0fe-e733-7dbf-8b3c-c4237c224c23" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherNoncurrentAssets_019cd0fe-e733-7f9d-a230-7782d96e99f2" xlink:href="vrt-20260331.xsd#vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherNoncurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7c3f-bea5-659a93c75053" xlink:to="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherNoncurrentAssets_019cd0fe-e733-7f9d-a230-7782d96e99f2" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillPurchaseAccountingAdjustments_019cd0fe-e733-7a1c-b002-0333627fcae5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillPurchaseAccountingAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7c3f-bea5-659a93c75053" xlink:to="loc_us-gaap_GoodwillPurchaseAccountingAdjustments_019cd0fe-e733-7a1c-b002-0333627fcae5" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_019cd0fe-e733-714c-8f36-936005f74a9e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7c3f-bea5-659a93c75053" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetUsefulLife_019cd0fe-e733-714c-8f36-936005f74a9e" xlink:type="arc" order="15"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/ACQUISITIONSRecognizedIdentifiedAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#ACQUISITIONSRecognizedIdentifiedAssetsAcquiredandLiabilitiesAssumedDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/ACQUISITIONSRecognizedIdentifiedAssetsAcquiredandLiabilitiesAssumedDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019cd0fe-e733-7a1a-8463-6f8a19caa6e1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019cd0fe-e733-7a1a-8463-6f8a19caa6e1" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019cd0fe-e733-7a9f-aeff-b33684f1af0f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019cd0fe-e733-7a1a-8463-6f8a19caa6e1" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019cd0fe-e733-7a9f-aeff-b33684f1af0f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd0fe-e733-7a9f-aeff-b33684f1af0f_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019cd0fe-e733-7a9f-aeff-b33684f1af0f" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd0fe-e733-7a9f-aeff-b33684f1af0f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd0fe-e733-72b4-88a0-06e43647ea44" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019cd0fe-e733-7a9f-aeff-b33684f1af0f" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd0fe-e733-72b4-88a0-06e43647ea44" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_PurgeRiteIntermediateLLCMember_019cd0fe-e733-77aa-9595-1698835a21f9" xlink:href="vrt-20260331.xsd#vrt_PurgeRiteIntermediateLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd0fe-e733-72b4-88a0-06e43647ea44" xlink:to="loc_vrt_PurgeRiteIntermediateLLCMember_019cd0fe-e733-77aa-9595-1698835a21f9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_019cd0fe-e733-721d-b1fb-a0e8d83773ae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsReceivables_019cd0fe-e733-721d-b1fb-a0e8d83773ae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsReceivable_019d8504-8f85-7d6a-a9b1-9ef8ecbf9e6c" xlink:href="vrt-20260331.xsd#vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsReceivable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsReceivable_019d8504-8f85-7d6a-a9b1-9ef8ecbf9e6c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther_019cd0fe-e733-74db-85c8-8e79af9eebc2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentAssetsOther_019cd0fe-e733-74db-85c8-8e79af9eebc2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherCurrentAssets_019d8504-8f85-70c7-a1e1-6a578f35e31c" xlink:href="vrt-20260331.xsd#vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherCurrentAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherCurrentAssets_019d8504-8f85-70c7-a1e1-6a578f35e31c" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_019cd0fe-e733-753b-8ed5-c54016f73035" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedPropertyPlantAndEquipment_019cd0fe-e733-753b-8ed5-c54016f73035" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPropertyPlantAndEquipment_019d8504-8f85-7c86-88b1-e6c950da7313" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentPropertyPlantAndEquipment_019d8504-8f85-7c86-88b1-e6c950da7313" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Goodwill_019cd0fe-e733-70cb-a7ad-f579fd546759" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Goodwill"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_us-gaap_Goodwill_019cd0fe-e733-70cb-a7ad-f579fd546759" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GoodwillPurchaseAccountingAdjustments_019d8504-8f85-77f8-ac3c-718e95e9cfb0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GoodwillPurchaseAccountingAdjustments"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_us-gaap_GoodwillPurchaseAccountingAdjustments_019d8504-8f85-77f8-ac3c-718e95e9cfb0" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_019cd0fe-e733-7c16-a236-a274ce0c1e00" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedIntangibles_019cd0fe-e733-7c16-a236-a274ce0c1e00" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherIntangibleAssets_019d8504-8f85-7d76-8cfb-06cd552c9b84" xlink:href="vrt-20260331.xsd#vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherIntangibleAssets_019d8504-8f85-7d76-8cfb-06cd552c9b84" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_BusinessCombinationRecognizedAssetAcquiredRightOfUseAssetsNet_019cd0fe-e733-78c4-a9d1-3e78873ae263" xlink:href="vrt-20260331.xsd#vrt_BusinessCombinationRecognizedAssetAcquiredRightOfUseAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_vrt_BusinessCombinationRecognizedAssetAcquiredRightOfUseAssetsNet_019cd0fe-e733-78c4-a9d1-3e78873ae263" xlink:type="arc" order="10"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentRightOfUseAssetsNet_019d8504-8f85-7fd2-8177-0e4e452c17fd" xlink:href="vrt-20260331.xsd#vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentRightOfUseAssetsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentRightOfUseAssetsNet_019d8504-8f85-7fd2-8177-0e4e452c17fd" xlink:type="arc" order="11"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_019cd0fe-e733-7a63-803c-41d5179805ec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesAccountsPayable_019cd0fe-e733-7a63-803c-41d5179805ec" xlink:type="arc" order="12"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsPayable_019d8504-8f85-7877-bf90-3660730b6138" xlink:href="vrt-20260331.xsd#vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsPayable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccountsPayable_019d8504-8f85-7877-bf90-3660730b6138" xlink:type="arc" order="13"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue_019cd0fe-e733-71c5-b3f3-876836fab81b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedCurrentLiabilitiesDeferredRevenue_019cd0fe-e733-71c5-b3f3-876836fab81b" xlink:type="arc" order="14"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredRevenue_019d8504-8f85-7cb7-8bed-3432d9ba897d" xlink:href="vrt-20260331.xsd#vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredRevenue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredRevenue_019d8504-8f85-7cb7-8bed-3432d9ba897d" xlink:type="arc" order="15"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAccruedExpensesAndOtherLiabilities_019cd0fe-e733-7c3c-a2b9-4a28df74e182" xlink:href="vrt-20260331.xsd#vrt_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAccruedExpensesAndOtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_vrt_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedAccruedExpensesAndOtherLiabilities_019cd0fe-e733-7c3c-a2b9-4a28df74e182" xlink:type="arc" order="16"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccruedExpensesAndOtherLiabilities_019d8504-8f85-76b2-8fce-e9c14bb924c2" xlink:href="vrt-20260331.xsd#vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccruedExpensesAndOtherLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentAccruedExpensesAndOtherLiabilities_019d8504-8f85-76b2-8fce-e9c14bb924c2" xlink:type="arc" order="17"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_019cd0fe-e733-793a-b59c-996b3810b3b8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedDeferredTaxLiabilities_019cd0fe-e733-793a-b59c-996b3810b3b8" xlink:type="arc" order="18"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredIncomeTaxes_019d8504-8f85-7f5f-a613-9a404d9882d1" xlink:href="vrt-20260331.xsd#vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredIncomeTaxes"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentDeferredIncomeTaxes_019d8504-8f85-7f5f-a613-9a404d9882d1" xlink:type="arc" order="19"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt_019cd0fe-e733-7af1-97d3-b173e344c727" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredAndLiabilitiesAssumedNoncurrentLiabilitiesLongTermDebt_019cd0fe-e733-7af1-97d3-b173e344c727" xlink:type="arc" order="20"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherLongTermLiabilities_019d8504-8f85-7f57-8dc6-e3b8f9af066c" xlink:href="vrt-20260331.xsd#vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherLongTermLiabilities"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_vrt_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentOtherLongTermLiabilities_019d8504-8f85-7f57-8dc6-e3b8f9af066c" xlink:type="arc" order="21"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_019cd0fe-e733-7dd2-9569-c5a4ed2cfe2f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_us-gaap_BusinessCombinationRecognizedIdentifiableAssetsAcquiredGoodwillAndLiabilitiesAssumedNet_019cd0fe-e733-7dd2-9569-c5a4ed2cfe2f" xlink:type="arc" order="22"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentConsiderationTransferred_019d854e-d829-71a6-b8ae-74877cfa737a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentConsiderationTransferred"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-722c-8699-0d97c96e0e3c" xlink:to="loc_us-gaap_BusinessCombinationProvisionalInformationInitialAccountingIncompleteAdjustmentConsiderationTransferred_019d854e-d829-71a6-b8ae-74877cfa737a" xlink:type="arc" order="23"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/ACQUISITIONSIndefiniteLivedIntangibleAssetsAcquiredDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#ACQUISITIONSIndefiniteLivedIntangibleAssetsAcquiredDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/ACQUISITIONSIndefiniteLivedIntangibleAssetsAcquiredDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7823-98c4-836dac5c87b7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019cd0fe-e733-7dd2-82d2-bfd90ce797c0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7823-98c4-836dac5c87b7" xlink:to="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019cd0fe-e733-7dd2-82d2-bfd90ce797c0" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019cd0fe-e733-72ca-aea3-8f2b4d2e3032" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019cd0fe-e733-7dd2-82d2-bfd90ce797c0" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019cd0fe-e733-72ca-aea3-8f2b4d2e3032" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd0fe-e733-72ca-aea3-8f2b4d2e3032_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019cd0fe-e733-72ca-aea3-8f2b4d2e3032" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd0fe-e733-72ca-aea3-8f2b4d2e3032_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd0fe-e733-7927-ada6-c79f443fcbcf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019cd0fe-e733-72ca-aea3-8f2b4d2e3032" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd0fe-e733-7927-ada6-c79f443fcbcf" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_PurgeRiteIntermediateLLCMember_019cd0fe-e733-79d6-b68d-74bf44f86848" xlink:href="vrt-20260331.xsd#vrt_PurgeRiteIntermediateLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019cd0fe-e733-7927-ada6-c79f443fcbcf" xlink:to="loc_vrt_PurgeRiteIntermediateLLCMember_019cd0fe-e733-79d6-b68d-74bf44f86848" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019cd0fe-e733-7383-baec-ab5110d21fb2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfBusinessAcquisitionsByAcquisitionTable_019cd0fe-e733-7dd2-82d2-bfd90ce797c0" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019cd0fe-e733-7383-baec-ab5110d21fb2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd0fe-e733-7383-baec-ab5110d21fb2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019cd0fe-e733-7383-baec-ab5110d21fb2" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd0fe-e733-7383-baec-ab5110d21fb2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd0fe-e733-7e8e-81c7-50cf2f464a64" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsByMajorClassAxis_019cd0fe-e733-7383-baec-ab5110d21fb2" xlink:to="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd0fe-e733-7e8e-81c7-50cf2f464a64" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CustomerRelationshipsMember_019cd0fe-e733-702c-8835-365566c1703f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CustomerRelationshipsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd0fe-e733-7e8e-81c7-50cf2f464a64" xlink:to="loc_us-gaap_CustomerRelationshipsMember_019cd0fe-e733-702c-8835-365566c1703f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TrademarksMember_019cd0fe-e733-7540-846a-5c898107ed99" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TrademarksMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd0fe-e733-7e8e-81c7-50cf2f464a64" xlink:to="loc_us-gaap_TrademarksMember_019cd0fe-e733-7540-846a-5c898107ed99" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherIntangibleAssetsMember_019cd0fe-e733-7875-8d95-b82cb4883cba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherIntangibleAssetsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd0fe-e733-7e8e-81c7-50cf2f464a64" xlink:to="loc_us-gaap_OtherIntangibleAssetsMember_019cd0fe-e733-7875-8d95-b82cb4883cba" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SoftwareDevelopmentMember_019cd0fe-e733-7226-9c66-249b50b6ce81" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SoftwareDevelopmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FiniteLivedIntangibleAssetsMajorClassNameDomain_019cd0fe-e733-7e8e-81c7-50cf2f464a64" xlink:to="loc_us-gaap_SoftwareDevelopmentMember_019cd0fe-e733-7226-9c66-249b50b6ce81" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_019cd0fe-e733-7f0d-9c83-038f142113ef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7823-98c4-836dac5c87b7" xlink:to="loc_us-gaap_AcquiredFiniteLivedIntangibleAssetsWeightedAverageUsefulLife_019cd0fe-e733-7f0d-9c83-038f142113ef" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_019cd0fe-e733-79f0-8b06-651e217c5ec9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FinitelivedIntangibleAssetsAcquired1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionLineItems_019cd0fe-e733-7823-98c4-836dac5c87b7" xlink:to="loc_us-gaap_FinitelivedIntangibleAssetsAcquired1_019cd0fe-e733-79f0-8b06-651e217c5ec9" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/REVENUEDisaggregationofRevenueDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#REVENUEDisaggregationofRevenueDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/REVENUEDisaggregationofRevenueDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueLineItems_019b130c-4943-7512-995b-8963c1f000bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DisaggregationOfRevenueTable_019b130c-4943-700a-b884-d1bc42f60368" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DisaggregationOfRevenueTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019b130c-4943-7512-995b-8963c1f000bb" xlink:to="loc_us-gaap_DisaggregationOfRevenueTable_019b130c-4943-700a-b884-d1bc42f60368" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-4943-71f8-b1f8-dfefdb8cef89" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019b130c-4943-700a-b884-d1bc42f60368" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-4943-71f8-b1f8-dfefdb8cef89" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019b130c-4943-71f8-b1f8-dfefdb8cef89_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-4943-71f8-b1f8-dfefdb8cef89" xlink:to="loc_us-gaap_SegmentDomain_019b130c-4943-71f8-b1f8-dfefdb8cef89_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019b130c-4943-7668-8e24-2258384786af" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-4943-71f8-b1f8-dfefdb8cef89" xlink:to="loc_us-gaap_SegmentDomain_019b130c-4943-7668-8e24-2258384786af" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_AmericasSegmentMember_019b130c-4943-7279-b9ee-fae8122b1bce" xlink:href="vrt-20260331.xsd#vrt_AmericasSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b130c-4943-7668-8e24-2258384786af" xlink:to="loc_vrt_AmericasSegmentMember_019b130c-4943-7279-b9ee-fae8122b1bce" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_AsiaPacificSegmentMember_019b130c-4943-7a4d-bc59-75fbc3ab46c2" xlink:href="vrt-20260331.xsd#vrt_AsiaPacificSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b130c-4943-7668-8e24-2258384786af" xlink:to="loc_vrt_AsiaPacificSegmentMember_019b130c-4943-7a4d-bc59-75fbc3ab46c2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_EMEASegmentMember_019b130c-4943-7f47-bd0e-e5e1ba7d8eec" xlink:href="vrt-20260331.xsd#vrt_EMEASegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b130c-4943-7668-8e24-2258384786af" xlink:to="loc_vrt_EMEASegmentMember_019b130c-4943-7f47-bd0e-e5e1ba7d8eec" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductOrServiceAxis_019b130c-4943-7bdf-b86c-64540f07767f" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019b130c-4943-700a-b884-d1bc42f60368" xlink:to="loc_srt_ProductOrServiceAxis_019b130c-4943-7bdf-b86c-64540f07767f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019b130c-4943-7bdf-b86c-64540f07767f_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ProductOrServiceAxis_019b130c-4943-7bdf-b86c-64540f07767f" xlink:to="loc_srt_ProductsAndServicesDomain_019b130c-4943-7bdf-b86c-64540f07767f_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ProductsAndServicesDomain_019b130c-4943-7ad6-8e48-1df3ee46d679" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ProductsAndServicesDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ProductOrServiceAxis_019b130c-4943-7bdf-b86c-64540f07767f" xlink:to="loc_srt_ProductsAndServicesDomain_019b130c-4943-7ad6-8e48-1df3ee46d679" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_ProductExcludingSparesMember_019b130c-4943-7c3a-b0c0-8cd40ec03070" xlink:href="vrt-20260331.xsd#vrt_ProductExcludingSparesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019b130c-4943-7ad6-8e48-1df3ee46d679" xlink:to="loc_vrt_ProductExcludingSparesMember_019b130c-4943-7c3a-b0c0-8cd40ec03070" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_ServicesAndSparesMember_019b130c-4943-7552-9b8a-695ea6bd7708" xlink:href="vrt-20260331.xsd#vrt_ServicesAndSparesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ProductsAndServicesDomain_019b130c-4943-7ad6-8e48-1df3ee46d679" xlink:to="loc_vrt_ServicesAndSparesMember_019b130c-4943-7552-9b8a-695ea6bd7708" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_019b130c-4943-7747-ab4c-07c69711fe84" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TimingOfTransferOfGoodOrServiceAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DisaggregationOfRevenueTable_019b130c-4943-700a-b884-d1bc42f60368" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_019b130c-4943-7747-ab4c-07c69711fe84" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_019b130c-4943-7747-ab4c-07c69711fe84_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TimingOfTransferOfGoodOrServiceDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_019b130c-4943-7747-ab4c-07c69711fe84" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_019b130c-4943-7747-ab4c-07c69711fe84_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_019b130c-4943-7cc1-a657-a37dee5f478e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TimingOfTransferOfGoodOrServiceDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceAxis_019b130c-4943-7747-ab4c-07c69711fe84" xlink:to="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_019b130c-4943-7cc1-a657-a37dee5f478e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransferredAtPointInTimeMember_019b130c-4943-7b04-a6ba-68b7ced07eae" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransferredAtPointInTimeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_019b130c-4943-7cc1-a657-a37dee5f478e" xlink:to="loc_us-gaap_TransferredAtPointInTimeMember_019b130c-4943-7b04-a6ba-68b7ced07eae" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TransferredOverTimeMember_019b130c-4943-7f38-a727-14106f5a17cb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TransferredOverTimeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TimingOfTransferOfGoodOrServiceDomain_019b130c-4943-7cc1-a657-a37dee5f478e" xlink:to="loc_us-gaap_TransferredOverTimeMember_019b130c-4943-7f38-a727-14106f5a17cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019b130c-4943-7706-90a1-b41d1a8f9e0d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DisaggregationOfRevenueLineItems_019b130c-4943-7512-995b-8963c1f000bb" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019b130c-4943-7706-90a1-b41d1a8f9e0d" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/REVENUENarrativeDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#REVENUENarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/REVENUENarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019b130c-4943-77ab-8a08-ec358d5fbe5b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019b130c-4943-7de2-9c16-ceb0d374fa3b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019b130c-4943-77ab-8a08-ec358d5fbe5b" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019b130c-4943-7de2-9c16-ceb0d374fa3b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_019b130c-4943-7825-9f8d-0b9dfc0eb5ba" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019b130c-4943-7de2-9c16-ceb0d374fa3b" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionStartDateAxis_019b130c-4943-7825-9f8d-0b9dfc0eb5ba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_019b130c-4943-71fa-bb20-072ad6ccfc00" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019b130c-4943-77ab-8a08-ec358d5fbe5b" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_019b130c-4943-71fa-bb20-072ad6ccfc00" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_019b130c-4943-74a5-a1af-57ff99123835" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019b130c-4943-77ab-8a08-ec358d5fbe5b" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_019b130c-4943-74a5-a1af-57ff99123835" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019b130c-4943-70d5-86d0-c168076a37fa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019b130c-4943-77ab-8a08-ec358d5fbe5b" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019b130c-4943-70d5-86d0-c168076a37fa" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/REVENUENarrativeDetails_1" xlink:type="simple" xlink:href="vrt-20260331.xsd#REVENUENarrativeDetails_1"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/REVENUENarrativeDetails_1" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019b130c-4943-77ab-8a08-ec358d5fbe5b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019b130c-4943-7de2-9c16-ceb0d374fa3b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019b130c-4943-77ab-8a08-ec358d5fbe5b" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionTable_019b130c-4943-7de2-9c16-ceb0d374fa3b" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_019b130c-4943-71fa-bb20-072ad6ccfc00" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ContractWithCustomerLiabilityRevenueRecognized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019b130c-4943-77ab-8a08-ec358d5fbe5b" xlink:to="loc_us-gaap_ContractWithCustomerLiabilityRevenueRecognized_019b130c-4943-71fa-bb20-072ad6ccfc00" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligation_019b130c-4943-74a5-a1af-57ff99123835" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligation"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019b130c-4943-77ab-8a08-ec358d5fbe5b" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligation_019b130c-4943-74a5-a1af-57ff99123835" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019b130c-4943-70d5-86d0-c168076a37fa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionLineItems_019b130c-4943-77ab-8a08-ec358d5fbe5b" xlink:to="loc_us-gaap_RevenueRemainingPerformanceObligationExpectedTimingOfSatisfactionPeriod1_019b130c-4943-70d5-86d0-c168076a37fa" xlink:type="arc" order="2"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/RESTRUCTURINGCOSTSRestructuringCostsbySegmentDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#RESTRUCTURINGCOSTSRestructuringCostsbySegmentDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/RESTRUCTURINGCOSTSRestructuringCostsbySegmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019b130c-4943-76de-8029-769a978723dc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019b130c-4943-7bfb-91f3-dac013f4c00a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019b130c-4943-76de-8029-769a978723dc" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019b130c-4943-7bfb-91f3-dac013f4c00a" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019b130c-4943-726e-b467-616c7d7ea59c" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019b130c-4943-7bfb-91f3-dac013f4c00a" xlink:to="loc_srt_ConsolidationItemsAxis_019b130c-4943-726e-b467-616c7d7ea59c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019b130c-4943-726e-b467-616c7d7ea59c_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019b130c-4943-726e-b467-616c7d7ea59c" xlink:to="loc_srt_ConsolidationItemsDomain_019b130c-4943-726e-b467-616c7d7ea59c_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019b130c-4943-7ebc-b4c0-9485dcdd4f91" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019b130c-4943-726e-b467-616c7d7ea59c" xlink:to="loc_srt_ConsolidationItemsDomain_019b130c-4943-7ebc-b4c0-9485dcdd4f91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_019b130c-4943-7453-ab30-56fe25666bb6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019b130c-4943-7ebc-b4c0-9485dcdd4f91" xlink:to="loc_us-gaap_OperatingSegmentsMember_019b130c-4943-7453-ab30-56fe25666bb6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_019b130c-4943-75db-8177-c6604f8d51d3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019b130c-4943-7ebc-b4c0-9485dcdd4f91" xlink:to="loc_us-gaap_CorporateNonSegmentMember_019b130c-4943-75db-8177-c6604f8d51d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-4943-7374-a762-b31056a7c3de" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019b130c-4943-7bfb-91f3-dac013f4c00a" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-4943-7374-a762-b31056a7c3de" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019b130c-4943-7374-a762-b31056a7c3de_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-4943-7374-a762-b31056a7c3de" xlink:to="loc_us-gaap_SegmentDomain_019b130c-4943-7374-a762-b31056a7c3de_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019b130c-4943-7fb4-aa63-01ea3cc6e173" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-4943-7374-a762-b31056a7c3de" xlink:to="loc_us-gaap_SegmentDomain_019b130c-4943-7fb4-aa63-01ea3cc6e173" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_AmericasSegmentMember_019b130c-4943-7c0d-a852-ad05d7e11afd" xlink:href="vrt-20260331.xsd#vrt_AmericasSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b130c-4943-7fb4-aa63-01ea3cc6e173" xlink:to="loc_vrt_AmericasSegmentMember_019b130c-4943-7c0d-a852-ad05d7e11afd" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_AsiaPacificSegmentMember_019b130c-4943-71a3-9f22-c3d2dd66598f" xlink:href="vrt-20260331.xsd#vrt_AsiaPacificSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b130c-4943-7fb4-aa63-01ea3cc6e173" xlink:to="loc_vrt_AsiaPacificSegmentMember_019b130c-4943-71a3-9f22-c3d2dd66598f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_EMEASegmentMember_019b130c-4943-7a4f-bab7-856d395f1384" xlink:href="vrt-20260331.xsd#vrt_EMEASegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b130c-4943-7fb4-aa63-01ea3cc6e173" xlink:to="loc_vrt_EMEASegmentMember_019b130c-4943-7a4f-bab7-856d395f1384" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_019b130c-4943-7718-97b3-c77f74366433" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019b130c-4943-76de-8029-769a978723dc" xlink:to="loc_us-gaap_RestructuringCharges_019b130c-4943-7718-97b3-c77f74366433" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/RESTRUCTURINGCOSTSScheduleofChangesinRestructuringReserveDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#RESTRUCTURINGCOSTSScheduleofChangesinRestructuringReserveDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/RESTRUCTURINGCOSTSScheduleofChangesinRestructuringReserveDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveLineItems_019b130c-4943-7633-802d-0723c91ad79e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019b130c-4943-7be4-a230-2eaaafea1c60" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfRestructuringAndRelatedCostsTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019b130c-4943-7633-802d-0723c91ad79e" xlink:to="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019b130c-4943-7be4-a230-2eaaafea1c60" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCostAndReserveAxis_019b130c-4943-7981-8517-ffd93bed5f60" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCostAndReserveAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfRestructuringAndRelatedCostsTable_019b130c-4943-7be4-a230-2eaaafea1c60" xlink:to="loc_us-gaap_RestructuringCostAndReserveAxis_019b130c-4943-7981-8517-ffd93bed5f60" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019b130c-4943-7981-8517-ffd93bed5f60_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019b130c-4943-7981-8517-ffd93bed5f60" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019b130c-4943-7981-8517-ffd93bed5f60_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TypeOfRestructuringDomain_019b130c-4943-76c5-b7de-ce445a816d18" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TypeOfRestructuringDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_RestructuringCostAndReserveAxis_019b130c-4943-7981-8517-ffd93bed5f60" xlink:to="loc_us-gaap_TypeOfRestructuringDomain_019b130c-4943-76c5-b7de-ce445a816d18" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeSeveranceMember_019b130c-4943-7f9c-ace0-4566077913a8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeSeveranceMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019b130c-4943-76c5-b7de-ce445a816d18" xlink:to="loc_us-gaap_EmployeeSeveranceMember_019b130c-4943-7f9c-ace0-4566077913a8" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FacilityClosingMember_019b130c-4943-70fe-a3b5-d5be5917517e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FacilityClosingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_TypeOfRestructuringDomain_019b130c-4943-76c5-b7de-ce445a816d18" xlink:to="loc_us-gaap_FacilityClosingMember_019b130c-4943-70fe-a3b5-d5be5917517e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringReserveRollForward_019b130c-4943-72f9-9b88-0d63803f87be" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringReserveRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringCostAndReserveLineItems_019b130c-4943-7633-802d-0723c91ad79e" xlink:to="loc_us-gaap_RestructuringReserveRollForward_019b130c-4943-72f9-9b88-0d63803f87be" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_RestructuringReserveNet_019b130c-4943-7700-91df-8543f0c4caf4" xlink:href="vrt-20260331.xsd#vrt_RestructuringReserveNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_019b130c-4943-72f9-9b88-0d63803f87be" xlink:to="loc_vrt_RestructuringReserveNet_019b130c-4943-7700-91df-8543f0c4caf4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsForRestructuring_019b130c-4943-7125-80ed-a52a64361f2b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsForRestructuring"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_019b130c-4943-72f9-9b88-0d63803f87be" xlink:to="loc_us-gaap_PaymentsForRestructuring_019b130c-4943-7125-80ed-a52a64361f2b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_RestructuringChargesAndAccrualAdjustment_019b130c-4943-7301-be87-5448a61240a7" xlink:href="vrt-20260331.xsd#vrt_RestructuringChargesAndAccrualAdjustment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_RestructuringReserveRollForward_019b130c-4943-72f9-9b88-0d63803f87be" xlink:to="loc_vrt_RestructuringChargesAndAccrualAdjustment_019b130c-4943-7301-be87-5448a61240a7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_RestructuringReserveNet_019b130c-49f5-7a08-ad91-a8dbc3406ea7" xlink:href="vrt-20260331.xsd#vrt_RestructuringReserveNet"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/DEBTScheduleofDebtDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#DEBTScheduleofDebtDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/DEBTScheduleofDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019b130c-49f5-7cb2-8af0-b2b247891d16" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019b130c-49f5-7fff-9d66-fb55be544e28" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b130c-49f5-7cb2-8af0-b2b247891d16" xlink:to="loc_us-gaap_DebtInstrumentTable_019b130c-49f5-7fff-9d66-fb55be544e28" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019b130c-49f5-7600-a8c1-8305a8ba05e2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019b130c-49f5-7fff-9d66-fb55be544e28" xlink:to="loc_us-gaap_DebtInstrumentAxis_019b130c-49f5-7600-a8c1-8305a8ba05e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-7600-a8c1-8305a8ba05e2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019b130c-49f5-7600-a8c1-8305a8ba05e2" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-7600-a8c1-8305a8ba05e2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-76f1-a715-25842e1e700f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019b130c-49f5-7600-a8c1-8305a8ba05e2" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-76f1-a715-25842e1e700f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_TermLoanDue2032Member_019b130c-49f5-722c-8f04-a366781d2b86" xlink:href="vrt-20260331.xsd#vrt_TermLoanDue2032Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-76f1-a715-25842e1e700f" xlink:to="loc_vrt_TermLoanDue2032Member_019b130c-49f5-722c-8f04-a366781d2b86" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_SeniorSecuredNotesDue2028Member_019b130c-49f5-746d-8380-6d94b9f0ac21" xlink:href="vrt-20260331.xsd#vrt_SeniorSecuredNotesDue2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-76f1-a715-25842e1e700f" xlink:to="loc_vrt_SeniorSecuredNotesDue2028Member_019b130c-49f5-746d-8380-6d94b9f0ac21" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_SeniorNotesDue2036Member_019d27c7-0fa0-7262-b344-747a86a7b0d9" xlink:href="vrt-20260331.xsd#vrt_SeniorNotesDue2036Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-76f1-a715-25842e1e700f" xlink:to="loc_vrt_SeniorNotesDue2036Member_019d27c7-0fa0-7262-b344-747a86a7b0d9" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_SeniorNotesDue2046Member_019d27c7-5de8-7e84-9a71-6de08a7eff5f" xlink:href="vrt-20260331.xsd#vrt_SeniorNotesDue2046Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-76f1-a715-25842e1e700f" xlink:to="loc_vrt_SeniorNotesDue2046Member_019d27c7-5de8-7e84-9a71-6de08a7eff5f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_SeniorNotesDue2056Member_019d27c7-9f1b-7717-8797-f7a06d88dc21" xlink:href="vrt-20260331.xsd#vrt_SeniorNotesDue2056Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-76f1-a715-25842e1e700f" xlink:to="loc_vrt_SeniorNotesDue2056Member_019d27c7-9f1b-7717-8797-f7a06d88dc21" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_SeniorNotesDue2066Member_019d27c7-dc12-7c91-83f8-fb76239809d5" xlink:href="vrt-20260331.xsd#vrt_SeniorNotesDue2066Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-76f1-a715-25842e1e700f" xlink:to="loc_vrt_SeniorNotesDue2066Member_019d27c7-dc12-7c91-83f8-fb76239809d5" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019b130c-49f5-72aa-bbcc-ccf0953eec76" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019b130c-49f5-7fff-9d66-fb55be544e28" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019b130c-49f5-72aa-bbcc-ccf0953eec76" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019b130c-49f5-72aa-bbcc-ccf0953eec76_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019b130c-49f5-72aa-bbcc-ccf0953eec76" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019b130c-49f5-72aa-bbcc-ccf0953eec76_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019b130c-49f5-7223-8cc4-913f14d3b013" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019b130c-49f5-72aa-bbcc-ccf0953eec76" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019b130c-49f5-7223-8cc4-913f14d3b013" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019b130c-49f5-7867-901b-22b2a9279842" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019b130c-49f5-7223-8cc4-913f14d3b013" xlink:to="loc_us-gaap_LineOfCreditMember_019b130c-49f5-7867-901b-22b2a9279842" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019d4879-b1b6-775a-bb9c-f03cb16210c4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019b130c-49f5-7223-8cc4-913f14d3b013" xlink:to="loc_us-gaap_SeniorNotesMember_019d4879-b1b6-775a-bb9c-f03cb16210c4" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019b130c-49f5-7582-bbe9-a5f0bfb97a98" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019b130c-49f5-7fff-9d66-fb55be544e28" xlink:to="loc_us-gaap_CreditFacilityAxis_019b130c-49f5-7582-bbe9-a5f0bfb97a98" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019b130c-49f5-7582-bbe9-a5f0bfb97a98_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019b130c-49f5-7582-bbe9-a5f0bfb97a98" xlink:to="loc_us-gaap_CreditFacilityDomain_019b130c-49f5-7582-bbe9-a5f0bfb97a98_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019b130c-49f5-75bb-9642-eed7f71346d7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019b130c-49f5-7582-bbe9-a5f0bfb97a98" xlink:to="loc_us-gaap_CreditFacilityDomain_019b130c-49f5-75bb-9642-eed7f71346d7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019b130c-49f5-758c-8b97-a037a13fe105" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019b130c-49f5-75bb-9642-eed7f71346d7" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019b130c-49f5-758c-8b97-a037a13fe105" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtWeightedAverageInterestRate_019b130c-49f5-7c8f-afe1-e1f3b5d9f178" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtWeightedAverageInterestRate"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b130c-49f5-7cb2-8af0-b2b247891d16" xlink:to="loc_us-gaap_DebtWeightedAverageInterestRate_019b130c-49f5-7c8f-afe1-e1f3b5d9f178" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019d4877-1368-7371-aae5-a276d978ae9a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b130c-49f5-7cb2-8af0-b2b247891d16" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019d4877-1368-7371-aae5-a276d978ae9a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_019b130c-49f5-70fc-8493-330c3dde2e51" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b130c-49f5-7cb2-8af0-b2b247891d16" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_019b130c-49f5-70fc-8493-330c3dde2e51" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019b130c-49f5-715f-accf-875213f9b045" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b130c-49f5-7cb2-8af0-b2b247891d16" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019b130c-49f5-715f-accf-875213f9b045" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_019b130c-49f5-7942-a146-e971ebffb5c4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b130c-49f5-7cb2-8af0-b2b247891d16" xlink:to="loc_us-gaap_DebtInstrumentUnamortizedDiscountPremiumAndDebtIssuanceCostsNet_019b130c-49f5-7942-a146-e971ebffb5c4" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebt_019b130c-49f5-7c50-9a40-557c7068cade" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b130c-49f5-7cb2-8af0-b2b247891d16" xlink:to="loc_us-gaap_LongTermDebt_019b130c-49f5-7c50-9a40-557c7068cade" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtCurrent_019b130c-49f5-7dd1-9b20-2b275101be58" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b130c-49f5-7cb2-8af0-b2b247891d16" xlink:to="loc_us-gaap_LongTermDebtCurrent_019b130c-49f5-7dd1-9b20-2b275101be58" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtNoncurrent_019b130c-49f5-7a04-a897-b6503301d08a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019b130c-49f5-7cb2-8af0-b2b247891d16" xlink:to="loc_us-gaap_LongTermDebtNoncurrent_019b130c-49f5-7a04-a897-b6503301d08a" xlink:type="arc" order="7"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/DEBTNarrativeDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#DEBTNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/DEBTNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentLineItems_019d27e1-c944-7c5b-8215-640f4d3d8724" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentTable_019b130c-49f5-7563-b0d7-49653406e4b6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019d27e1-c944-7c5b-8215-640f4d3d8724" xlink:to="loc_us-gaap_DebtInstrumentTable_019b130c-49f5-7563-b0d7-49653406e4b6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019d27e1-c944-7ed5-92bd-1bcebde58c8a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019b130c-49f5-7563-b0d7-49653406e4b6" xlink:to="loc_us-gaap_DebtInstrumentAxis_019d27e1-c944-7ed5-92bd-1bcebde58c8a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019d27e1-c944-7ed5-92bd-1bcebde58c8a_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019d27e1-c944-7ed5-92bd-1bcebde58c8a" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019d27e1-c944-7ed5-92bd-1bcebde58c8a_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019d27e1-c944-753f-bc16-17c4a71fd7b9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019d27e1-c944-7ed5-92bd-1bcebde58c8a" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019d27e1-c944-753f-bc16-17c4a71fd7b9" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_SeniorUnsecuredNotesMember_019d4d3e-88f0-77c0-9c27-41133cfb6b30" xlink:href="vrt-20260331.xsd#vrt_SeniorUnsecuredNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019d27e1-c944-753f-bc16-17c4a71fd7b9" xlink:to="loc_vrt_SeniorUnsecuredNotesMember_019d4d3e-88f0-77c0-9c27-41133cfb6b30" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_SeniorNotesDue2036Member_019d4d3e-88f0-794c-b863-63db28afbe46" xlink:href="vrt-20260331.xsd#vrt_SeniorNotesDue2036Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019d27e1-c944-753f-bc16-17c4a71fd7b9" xlink:to="loc_vrt_SeniorNotesDue2036Member_019d4d3e-88f0-794c-b863-63db28afbe46" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_SeniorNotesDue2046Member_019d4d3e-88f0-7540-908b-c4e59a42d342" xlink:href="vrt-20260331.xsd#vrt_SeniorNotesDue2046Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019d27e1-c944-753f-bc16-17c4a71fd7b9" xlink:to="loc_vrt_SeniorNotesDue2046Member_019d4d3e-88f0-7540-908b-c4e59a42d342" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_SeniorNotesDue2056Member_019d4d3e-88f0-75c8-8545-67e6f12862eb" xlink:href="vrt-20260331.xsd#vrt_SeniorNotesDue2056Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019d27e1-c944-753f-bc16-17c4a71fd7b9" xlink:to="loc_vrt_SeniorNotesDue2056Member_019d4d3e-88f0-75c8-8545-67e6f12862eb" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_SeniorNotesDue2066Member_019d4d3e-88f0-70a0-bfbb-5741ce9fb2bf" xlink:href="vrt-20260331.xsd#vrt_SeniorNotesDue2066Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019d27e1-c944-753f-bc16-17c4a71fd7b9" xlink:to="loc_vrt_SeniorNotesDue2066Member_019d4d3e-88f0-70a0-bfbb-5741ce9fb2bf" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_ABLRevolvingCreditFacilityMember_019d4d3f-6a3e-7366-9a69-2eb97dd06cd9" xlink:href="vrt-20260331.xsd#vrt_ABLRevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019d27e1-c944-753f-bc16-17c4a71fd7b9" xlink:to="loc_vrt_ABLRevolvingCreditFacilityMember_019d4d3f-6a3e-7366-9a69-2eb97dd06cd9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_019d4905-0152-7906-881a-204576b03471" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019b130c-49f5-7563-b0d7-49653406e4b6" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_019d4905-0152-7906-881a-204576b03471" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019d4905-0152-7906-881a-204576b03471_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_019d4905-0152-7906-881a-204576b03471" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019d4905-0152-7906-881a-204576b03471_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019d4905-0152-781a-8f7d-3992beee463a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodAxis_019d4905-0152-7906-881a-204576b03471" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019d4905-0152-781a-8f7d-3992beee463a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_019d4d3e-c9e5-7fc3-94f8-1777da8e0dec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodOneMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019d4905-0152-781a-8f7d-3992beee463a" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodOneMember_019d4d3e-c9e5-7fc3-94f8-1777da8e0dec" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_019d4d3e-c9e5-7d2f-9f83-a69c0b170232" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPeriodTwoMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentRedemptionPeriodDomain_019d4905-0152-781a-8f7d-3992beee463a" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPeriodTwoMember_019d4d3e-c9e5-7d2f-9f83-a69c0b170232" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019d4d3e-88f0-77a4-a9ec-03268615b126" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019b130c-49f5-7563-b0d7-49653406e4b6" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019d4d3e-88f0-77a4-a9ec-03268615b126" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019d4d3e-88f0-77a4-a9ec-03268615b126_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019d4d3e-88f0-77a4-a9ec-03268615b126" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019d4d3e-88f0-77a4-a9ec-03268615b126_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019d4d3e-88f0-77e0-a5c3-4423c391f2dd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019d4d3e-88f0-77a4-a9ec-03268615b126" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019d4d3e-88f0-77e0-a5c3-4423c391f2dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_UnsecuredDebtMember_019d4d3e-88f0-74f5-8676-e557a8200df2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_UnsecuredDebtMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019d4d3e-88f0-77e0-a5c3-4423c391f2dd" xlink:to="loc_us-gaap_UnsecuredDebtMember_019d4d3e-88f0-74f5-8676-e557a8200df2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019d4d3e-88f0-7cb7-82db-a3708914573f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019d4d3e-88f0-77e0-a5c3-4423c391f2dd" xlink:to="loc_us-gaap_SeniorNotesMember_019d4d3e-88f0-7cb7-82db-a3708914573f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditMember_019d4d3f-34b5-7550-98c0-7d1bd15c3628" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019d4d3e-88f0-77e0-a5c3-4423c391f2dd" xlink:to="loc_us-gaap_LineOfCreditMember_019d4d3f-34b5-7550-98c0-7d1bd15c3628" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityAxis_019d4d3f-34b5-7359-831f-02ff6efa96da" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019b130c-49f5-7563-b0d7-49653406e4b6" xlink:to="loc_us-gaap_CreditFacilityAxis_019d4d3f-34b5-7359-831f-02ff6efa96da" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019d4d3f-34b5-7359-831f-02ff6efa96da_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_CreditFacilityAxis_019d4d3f-34b5-7359-831f-02ff6efa96da" xlink:to="loc_us-gaap_CreditFacilityDomain_019d4d3f-34b5-7359-831f-02ff6efa96da_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CreditFacilityDomain_019d4d3f-34b5-7c91-aa1c-939a1e50f01a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CreditFacilityDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_CreditFacilityAxis_019d4d3f-34b5-7359-831f-02ff6efa96da" xlink:to="loc_us-gaap_CreditFacilityDomain_019d4d3f-34b5-7c91-aa1c-939a1e50f01a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019d4d3f-34b5-7288-8fc0-b496f71b045a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019d4d3f-34b5-7c91-aa1c-939a1e50f01a" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019d4d3f-34b5-7288-8fc0-b496f71b045a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_LettersOfCreditSubfacilityMember_019d6ab8-1f49-70a6-af0f-ce39beecb4db" xlink:href="vrt-20260331.xsd#vrt_LettersOfCreditSubfacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_CreditFacilityDomain_019d4d3f-34b5-7c91-aa1c-939a1e50f01a" xlink:to="loc_vrt_LettersOfCreditSubfacilityMember_019d6ab8-1f49-70a6-af0f-ce39beecb4db" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_DebtCovenantScenarioAxis_019d4d3f-6a3e-7abf-b3fc-4aed8cd23610" xlink:href="vrt-20260331.xsd#vrt_DebtCovenantScenarioAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_DebtInstrumentTable_019b130c-49f5-7563-b0d7-49653406e4b6" xlink:to="loc_vrt_DebtCovenantScenarioAxis_019d4d3f-6a3e-7abf-b3fc-4aed8cd23610" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_DebtCovenantScenarioDomain_019d4d3f-6a3e-7abf-b3fc-4aed8cd23610_default" xlink:href="vrt-20260331.xsd#vrt_DebtCovenantScenarioDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_vrt_DebtCovenantScenarioAxis_019d4d3f-6a3e-7abf-b3fc-4aed8cd23610" xlink:to="loc_vrt_DebtCovenantScenarioDomain_019d4d3f-6a3e-7abf-b3fc-4aed8cd23610_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_DebtCovenantScenarioDomain_019d4d3f-6a3e-727b-bf84-6a45f32dcf88" xlink:href="vrt-20260331.xsd#vrt_DebtCovenantScenarioDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_vrt_DebtCovenantScenarioAxis_019d4d3f-6a3e-7abf-b3fc-4aed8cd23610" xlink:to="loc_vrt_DebtCovenantScenarioDomain_019d4d3f-6a3e-727b-bf84-6a45f32dcf88" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_BaseCovenantMember_019d4d3f-6a3e-7a2d-8029-eca0476e0200" xlink:href="vrt-20260331.xsd#vrt_BaseCovenantMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vrt_DebtCovenantScenarioDomain_019d4d3f-6a3e-727b-bf84-6a45f32dcf88" xlink:to="loc_vrt_BaseCovenantMember_019d4d3f-6a3e-7a2d-8029-eca0476e0200" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_AcquisitionStepUpMember_019d4d3f-6a3e-7643-a320-c026985bdc49" xlink:href="vrt-20260331.xsd#vrt_AcquisitionStepUpMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_vrt_DebtCovenantScenarioDomain_019d4d3f-6a3e-727b-bf84-6a45f32dcf88" xlink:to="loc_vrt_AcquisitionStepUpMember_019d4d3f-6a3e-7643-a320-c026985bdc49" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFaceAmount_019d4d3e-88f0-7bd6-8f1d-ff021eede7c9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFaceAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019d27e1-c944-7c5b-8215-640f4d3d8724" xlink:to="loc_us-gaap_DebtInstrumentFaceAmount_019d4d3e-88f0-7bd6-8f1d-ff021eede7c9" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019d4d3e-88f0-733e-a41a-45979548272b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019d27e1-c944-7c5b-8215-640f4d3d8724" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019d4d3e-88f0-733e-a41a-45979548272b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_019d4d3e-c9e5-7bc6-a71c-855e5ad75ddd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentRedemptionPricePercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019d27e1-c944-7c5b-8215-640f4d3d8724" xlink:to="loc_us-gaap_DebtInstrumentRedemptionPricePercentage_019d4d3e-c9e5-7bc6-a71c-855e5ad75ddd" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019d4d3f-34b5-72bc-abab-17c44aa7d18f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019d27e1-c944-7c5b-8215-640f4d3d8724" xlink:to="loc_us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity_019d4d3f-34b5-72bc-abab-17c44aa7d18f" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongTermDebtTerm_019d9ba1-e3dd-766a-9c55-b0c2650bf430" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongTermDebtTerm"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019d27e1-c944-7c5b-8215-640f4d3d8724" xlink:to="loc_us-gaap_LongTermDebtTerm_019d9ba1-e3dd-766a-9c55-b0c2650bf430" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_DebtTermExtension_019d9ba2-c024-73b3-98cf-b86f840b2ba1" xlink:href="vrt-20260331.xsd#vrt_DebtTermExtension"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019d27e1-c944-7c5b-8215-640f4d3d8724" xlink:to="loc_vrt_DebtTermExtension_019d9ba2-c024-73b3-98cf-b86f840b2ba1" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_DebtInstrumentCovenantNetDebtToEBITDARatioMaximum_019d4d3f-6a3e-749c-aa41-223ce14bde5d" xlink:href="vrt-20260331.xsd#vrt_DebtInstrumentCovenantNetDebtToEBITDARatioMaximum"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019d27e1-c944-7c5b-8215-640f4d3d8724" xlink:to="loc_vrt_DebtInstrumentCovenantNetDebtToEBITDARatioMaximum_019d4d3f-6a3e-749c-aa41-223ce14bde5d" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019d4d3f-91de-7dbb-a695-11b557231d34" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019d27e1-c944-7c5b-8215-640f4d3d8724" xlink:to="loc_us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity_019d4d3f-91de-7dbb-a695-11b557231d34" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LettersOfCreditOutstandingAmount_019d4d3f-91de-7529-ab71-c93e48c48e9f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LettersOfCreditOutstandingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019d27e1-c944-7c5b-8215-640f4d3d8724" xlink:to="loc_us-gaap_LettersOfCreditOutstandingAmount_019d4d3f-91de-7529-ab71-c93e48c48e9f" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019d8565-a2bb-776b-8dbc-0b274f6bea46" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GainsLossesOnExtinguishmentOfDebt"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019d27e1-c944-7c5b-8215-640f4d3d8724" xlink:to="loc_us-gaap_GainsLossesOnExtinguishmentOfDebt_019d8565-a2bb-776b-8dbc-0b274f6bea46" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentCarryingAmount_019d4d3f-6a3e-7d4d-88e9-ecd0be3f658a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentCarryingAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentLineItems_019d27e1-c944-7c5b-8215-640f4d3d8724" xlink:to="loc_us-gaap_DebtInstrumentCarryingAmount_019d4d3f-6a3e-7d4d-88e9-ecd0be3f658a" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/OTHERFINANCIALINFORMATIONPropertyPlantAndEquipmentNetDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#OTHERFINANCIALINFORMATIONPropertyPlantAndEquipmentNetDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/OTHERFINANCIALINFORMATIONPropertyPlantAndEquipmentNetDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019b130c-49f5-7d9c-9bdf-7d2f387abd2a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019b130c-49f5-72d6-a750-486c396ea058" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfPropertyPlantAndEquipmentTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019b130c-49f5-7d9c-9bdf-7d2f387abd2a" xlink:to="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019b130c-49f5-72d6-a750-486c396ea058" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019b130c-49f5-70b7-995b-8a350d9f6596" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentByTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019b130c-49f5-72d6-a750-486c396ea058" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019b130c-49f5-70b7-995b-8a350d9f6596" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019b130c-49f5-70b7-995b-8a350d9f6596_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019b130c-49f5-70b7-995b-8a350d9f6596" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019b130c-49f5-70b7-995b-8a350d9f6596_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019b130c-49f5-7832-876f-b512936c3645" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentByTypeAxis_019b130c-49f5-70b7-995b-8a350d9f6596" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019b130c-49f5-7832-876f-b512936c3645" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MachineryAndEquipmentMember_019b130c-49f5-7fd9-8c6e-c97803a41b9b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MachineryAndEquipmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019b130c-49f5-7832-876f-b512936c3645" xlink:to="loc_us-gaap_MachineryAndEquipmentMember_019b130c-49f5-7fd9-8c6e-c97803a41b9b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BuildingMember_019b130c-49f5-7c9d-9443-4c9f5fcbe3c7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BuildingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019b130c-49f5-7832-876f-b512936c3645" xlink:to="loc_us-gaap_BuildingMember_019b130c-49f5-7c9d-9443-4c9f5fcbe3c7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LandMember_019b130c-49f5-77a7-b7d4-2ed0088db83b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LandMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019b130c-49f5-7832-876f-b512936c3645" xlink:to="loc_us-gaap_LandMember_019b130c-49f5-77a7-b7d4-2ed0088db83b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ConstructionInProgressMember_019b130c-49f5-7fa1-ad96-cbc0cea21874" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ConstructionInProgressMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentTypeDomain_019b130c-49f5-7832-876f-b512936c3645" xlink:to="loc_us-gaap_ConstructionInProgressMember_019b130c-49f5-7fa1-ad96-cbc0cea21874" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_StatementGeographicalAxis_019b130c-49f5-7299-87bd-55eb3b3da011" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_StatementGeographicalAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfPropertyPlantAndEquipmentTable_019b130c-49f5-72d6-a750-486c396ea058" xlink:to="loc_srt_StatementGeographicalAxis_019b130c-49f5-7299-87bd-55eb3b3da011" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019b130c-49f5-7299-87bd-55eb3b3da011_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_StatementGeographicalAxis_019b130c-49f5-7299-87bd-55eb3b3da011" xlink:to="loc_srt_SegmentGeographicalDomain_019b130c-49f5-7299-87bd-55eb3b3da011_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_SegmentGeographicalDomain_019b130c-49f5-798a-b398-38fc0c6e8db7" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_SegmentGeographicalDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_StatementGeographicalAxis_019b130c-49f5-7299-87bd-55eb3b3da011" xlink:to="loc_srt_SegmentGeographicalDomain_019b130c-49f5-798a-b398-38fc0c6e8db7" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_country_US_019b130c-49f5-7797-80fa-c3737da82934" xlink:href="https://xbrl.sec.gov/country/2025/country-2025.xsd#country_US"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_SegmentGeographicalDomain_019b130c-49f5-798a-b398-38fc0c6e8db7" xlink:to="loc_country_US_019b130c-49f5-7797-80fa-c3737da82934" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_019b130c-49f5-7431-8e9e-41ebe40c519f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019b130c-49f5-7d9c-9bdf-7d2f387abd2a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetBeforeAccumulatedDepreciationAndAmortization_019b130c-49f5-7431-8e9e-41ebe40c519f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_019b130c-49f5-7a46-b3cb-24119f58e147" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019b130c-49f5-7d9c-9bdf-7d2f387abd2a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAccumulatedDepreciationAndAmortization_019b130c-49f5-7a46-b3cb-24119f58e147" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_019b130c-49f5-7265-acad-de6d8791aa50" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019b130c-49f5-7d9c-9bdf-7d2f387abd2a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentAndFinanceLeaseRightOfUseAssetAfterAccumulatedDepreciationAndAmortization_019b130c-49f5-7265-acad-de6d8791aa50" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PropertyPlantAndEquipmentGross_019b130c-49f5-71d2-b177-69a72456ff6d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PropertyPlantAndEquipmentGross"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PropertyPlantAndEquipmentLineItems_019b130c-49f5-7d9c-9bdf-7d2f387abd2a" xlink:to="loc_us-gaap_PropertyPlantAndEquipmentGross_019b130c-49f5-71d2-b177-69a72456ff6d" xlink:type="arc" order="3"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/FINANCIALINSTRUMENTSANDRISKMANAGEMENTScheduleofFinancialAssetsandLiabilitiesMeasuredatFairValueHierarchyDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#FINANCIALINSTRUMENTSANDRISKMANAGEMENTScheduleofFinancialAssetsandLiabilitiesMeasuredatFairValueHierarchyDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/FINANCIALINSTRUMENTSANDRISKMANAGEMENTScheduleofFinancialAssetsandLiabilitiesMeasuredatFairValueHierarchyDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019b130c-49f5-7d96-b15c-94368ca0400e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019b130c-49f5-7e9e-a03b-62c12088a726" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019b130c-49f5-7d96-b15c-94368ca0400e" xlink:to="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019b130c-49f5-7e9e-a03b-62c12088a726" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019b130c-49f5-7a30-8a84-7f76c2b16368" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByFairValueHierarchyLevelAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019b130c-49f5-7e9e-a03b-62c12088a726" xlink:to="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019b130c-49f5-7a30-8a84-7f76c2b16368" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019b130c-49f5-7a30-8a84-7f76c2b16368_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019b130c-49f5-7a30-8a84-7f76c2b16368" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019b130c-49f5-7a30-8a84-7f76c2b16368_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019b130c-49f5-7c18-9b25-7db0a8eb23fd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueMeasurementsFairValueHierarchyDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByFairValueHierarchyLevelAxis_019b130c-49f5-7a30-8a84-7f76c2b16368" xlink:to="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019b130c-49f5-7c18-9b25-7db0a8eb23fd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel1Member_019b130c-49f5-7f4c-aed5-0c17642c4b1f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel1Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019b130c-49f5-7c18-9b25-7db0a8eb23fd" xlink:to="loc_us-gaap_FairValueInputsLevel1Member_019b130c-49f5-7f4c-aed5-0c17642c4b1f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel2Member_019b130c-49f5-7411-986c-f11234760b8e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel2Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019b130c-49f5-7c18-9b25-7db0a8eb23fd" xlink:to="loc_us-gaap_FairValueInputsLevel2Member_019b130c-49f5-7411-986c-f11234760b8e" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueInputsLevel3Member_019b130c-49f5-7126-88f5-f5c8d8c52b4c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueInputsLevel3Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueMeasurementsFairValueHierarchyDomain_019b130c-49f5-7c18-9b25-7db0a8eb23fd" xlink:to="loc_us-gaap_FairValueInputsLevel3Member_019b130c-49f5-7126-88f5-f5c8d8c52b4c" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019b130c-49f5-79da-918e-a5bb1141fe1e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisTable_019b130c-49f5-7e9e-a03b-62c12088a726" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019b130c-49f5-79da-918e-a5bb1141fe1e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019b130c-49f5-79da-918e-a5bb1141fe1e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019b130c-49f5-79da-918e-a5bb1141fe1e" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019b130c-49f5-79da-918e-a5bb1141fe1e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019b130c-49f5-75fe-849a-970d32d704a8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019b130c-49f5-79da-918e-a5bb1141fe1e" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019b130c-49f5-75fe-849a-970d32d704a8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_019b130c-49f5-7ee4-82d1-f7aaad427331" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019b130c-49f5-75fe-849a-970d32d704a8" xlink:to="loc_us-gaap_InterestRateSwapMember_019b130c-49f5-7ee4-82d1-f7aaad427331" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_019b130c-49f5-712c-8941-2602ca10aa9c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019b130c-49f5-75fe-849a-970d32d704a8" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_019b130c-49f5-712c-8941-2602ca10aa9c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_EconomicHedgeMember_019b130c-49f5-753a-af90-53575842423e" xlink:href="vrt-20260331.xsd#vrt_EconomicHedgeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019b130c-49f5-75fe-849a-970d32d704a8" xlink:to="loc_vrt_EconomicHedgeMember_019b130c-49f5-753a-af90-53575842423e" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019b130c-49f5-757a-82d8-c0d567a442cf" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CashAndCashEquivalentsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019b130c-49f5-7d96-b15c-94368ca0400e" xlink:to="loc_us-gaap_CashAndCashEquivalentsFairValueDisclosure_019b130c-49f5-757a-82d8-c0d567a442cf" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsCurrent_019b130c-49f5-74bb-add4-bad180c524ca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeAssetsCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019b130c-49f5-7d96-b15c-94368ca0400e" xlink:to="loc_us-gaap_DerivativeAssetsCurrent_019b130c-49f5-74bb-add4-bad180c524ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeAssetsNoncurrent_019b130c-49f5-76b2-be36-ddc9b4818be8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeAssetsNoncurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019b130c-49f5-7d96-b15c-94368ca0400e" xlink:to="loc_us-gaap_DerivativeAssetsNoncurrent_019b130c-49f5-76b2-be36-ddc9b4818be8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AssetsFairValueDisclosure_019b130c-49f5-7bf1-8d89-0d7d8cff04fd" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AssetsFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019b130c-49f5-7d96-b15c-94368ca0400e" xlink:to="loc_us-gaap_AssetsFairValueDisclosure_019b130c-49f5-7bf1-8d89-0d7d8cff04fd" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019cd591-681a-7f9e-9880-d30a33a9de82" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessCombinationContingentConsiderationLiability"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019b130c-49f5-7d96-b15c-94368ca0400e" xlink:to="loc_us-gaap_BusinessCombinationContingentConsiderationLiability_019cd591-681a-7f9e-9880-d30a33a9de82" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LiabilitiesFairValueDisclosure_019d27e9-1573-7494-a2fa-b7ce3a37ec79" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LiabilitiesFairValueDisclosure"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems_019b130c-49f5-7d96-b15c-94368ca0400e" xlink:to="loc_us-gaap_LiabilitiesFairValueDisclosure_019d27e9-1573-7494-a2fa-b7ce3a37ec79" xlink:type="arc" order="5"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/FINANCIALINSTRUMENTSANDRISKMANAGEMENTNarrativeDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#FINANCIALINSTRUMENTSANDRISKMANAGEMENTNarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/FINANCIALINSTRUMENTSANDRISKMANAGEMENTNarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019cd0a3-2254-75a0-adfa-4f08d24ac77e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019b130c-49f5-703e-9bf6-379193a403a6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019cd0a3-2254-75a0-adfa-4f08d24ac77e" xlink:to="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019b130c-49f5-703e-9bf6-379193a403a6" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd0a3-2254-72ab-bdbe-e80dfb0aa6ca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019b130c-49f5-703e-9bf6-379193a403a6" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd0a3-2254-72ab-bdbe-e80dfb0aa6ca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cd0a3-2254-72ab-bdbe-e80dfb0aa6ca_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd0a3-2254-72ab-bdbe-e80dfb0aa6ca" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cd0a3-2254-72ab-bdbe-e80dfb0aa6ca_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019cd0a3-2254-7ede-86d7-7f51e45198a5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019cd0a3-2254-72ab-bdbe-e80dfb0aa6ca" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019cd0a3-2254-7ede-86d7-7f51e45198a5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateSwapMember_019cd0a3-2254-72de-a0f8-ee01a399aec5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestRateSwapMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019cd0a3-2254-7ede-86d7-7f51e45198a5" xlink:to="loc_us-gaap_InterestRateSwapMember_019cd0a3-2254-72de-a0f8-ee01a399aec5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeContractMember_019cd0a4-2a95-7622-ad88-7680c2bc9676" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignExchangeContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019cd0a3-2254-7ede-86d7-7f51e45198a5" xlink:to="loc_us-gaap_ForeignExchangeContractMember_019cd0a4-2a95-7622-ad88-7680c2bc9676" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cd0a4-2a95-7578-b0cc-43e69d4efa5b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019cd0a3-2254-7ede-86d7-7f51e45198a5" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cd0a4-2a95-7578-b0cc-43e69d4efa5b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationAxis_019cd0a4-2a95-7355-b21e-442660c5a7e2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019b130c-49f5-703e-9bf6-379193a403a6" xlink:to="loc_us-gaap_HedgingDesignationAxis_019cd0a4-2a95-7355-b21e-442660c5a7e2" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cd0a4-2a95-7355-b21e-442660c5a7e2_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cd0a4-2a95-7355-b21e-442660c5a7e2" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cd0a4-2a95-7355-b21e-442660c5a7e2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingDesignationDomain_019cd0a4-2a95-7f12-9551-6d4aee7c8c06" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingDesignationDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_HedgingDesignationAxis_019cd0a4-2a95-7355-b21e-442660c5a7e2" xlink:to="loc_us-gaap_HedgingDesignationDomain_019cd0a4-2a95-7f12-9551-6d4aee7c8c06" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cd0a4-2a95-7d6a-a25f-1fdad114cb6d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DesignatedAsHedgingInstrumentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingDesignationDomain_019cd0a4-2a95-7f12-9551-6d4aee7c8c06" xlink:to="loc_us-gaap_DesignatedAsHedgingInstrumentMember_019cd0a4-2a95-7d6a-a25f-1fdad114cb6d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd0a4-2a95-73d8-b520-f4f379ef34f0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019b130c-49f5-703e-9bf6-379193a403a6" xlink:to="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd0a4-2a95-73d8-b520-f4f379ef34f0" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019cd0a4-2a95-73d8-b520-f4f379ef34f0_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd0a4-2a95-73d8-b520-f4f379ef34f0" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019cd0a4-2a95-73d8-b520-f4f379ef34f0_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_HedgingRelationshipDomain_019cd0a4-2a95-7ebb-a01f-4ebb82083c9b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_HedgingRelationshipDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentsGainLossByHedgingRelationshipAxis_019cd0a4-2a95-73d8-b520-f4f379ef34f0" xlink:to="loc_us-gaap_HedgingRelationshipDomain_019cd0a4-2a95-7ebb-a01f-4ebb82083c9b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_AluminumMember_019cd0a4-2a95-7e93-95d3-48ad0806a99e" xlink:href="vrt-20260331.xsd#vrt_AluminumMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019cd0a4-2a95-7ebb-a01f-4ebb82083c9b" xlink:to="loc_vrt_AluminumMember_019cd0a4-2a95-7e93-95d3-48ad0806a99e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_CopperMember_019cd0a4-2a95-771e-bea0-69336a13b9dd" xlink:href="vrt-20260331.xsd#vrt_CopperMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019cd0a4-2a95-7ebb-a01f-4ebb82083c9b" xlink:to="loc_vrt_CopperMember_019cd0a4-2a95-771e-bea0-69336a13b9dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_NetInvestmentHedgingMember_019cd0a4-2a95-74c6-823e-36fedc65000f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_NetInvestmentHedgingMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_HedgingRelationshipDomain_019cd0a4-2a95-7ebb-a01f-4ebb82083c9b" xlink:to="loc_us-gaap_NetInvestmentHedgingMember_019cd0a4-2a95-74c6-823e-36fedc65000f" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAxis_019ce305-1dfe-7ebb-9d8b-9edcf89f5981" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationTable_019b130c-49f5-703e-9bf6-379193a403a6" xlink:to="loc_us-gaap_BusinessAcquisitionAxis_019ce305-1dfe-7ebb-9d8b-9edcf89f5981" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019ce305-1dfe-7ebb-9d8b-9edcf89f5981_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019ce305-1dfe-7ebb-9d8b-9edcf89f5981" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019ce305-1dfe-7ebb-9d8b-9edcf89f5981_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019ce305-1dfe-75e2-9d2e-a35ac1dd5d3f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_BusinessAcquisitionAcquireeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_BusinessAcquisitionAxis_019ce305-1dfe-7ebb-9d8b-9edcf89f5981" xlink:to="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019ce305-1dfe-75e2-9d2e-a35ac1dd5d3f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_PurgeRiteIntermediateLLCMember_019ce305-1dfe-79ba-b1e7-2eea1f9a536a" xlink:href="vrt-20260331.xsd#vrt_PurgeRiteIntermediateLLCMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_BusinessAcquisitionAcquireeDomain_019ce305-1dfe-75e2-9d2e-a35ac1dd5d3f" xlink:to="loc_vrt_PurgeRiteIntermediateLLCMember_019ce305-1dfe-79ba-b1e7-2eea1f9a536a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherOperatingIncomeExpenseNet_019cd595-242a-75a2-b3af-e36604653eb5" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherOperatingIncomeExpenseNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019cd0a3-2254-75a0-adfa-4f08d24ac77e" xlink:to="loc_us-gaap_OtherOperatingIncomeExpenseNet_019cd595-242a-75a2-b3af-e36604653eb5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNotionalAmount_019cd0a3-2254-7d84-a42b-1d9725f3afe6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019cd0a3-2254-75a0-adfa-4f08d24ac77e" xlink:to="loc_us-gaap_DerivativeNotionalAmount_019cd0a3-2254-7d84-a42b-1d9725f3afe6" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_019cd0a3-2254-7992-9f2f-ac22222d705d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019cd0a3-2254-75a0-adfa-4f08d24ac77e" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax_019cd0a3-2254-7992-9f2f-ac22222d705d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossRealized_019cd0a4-2a95-7eca-9b22-1ca2d81a86ec" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignCurrencyTransactionGainLossRealized"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019cd0a3-2254-75a0-adfa-4f08d24ac77e" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossRealized_019cd0a4-2a95-7eca-9b22-1ca2d81a86ec" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeNonmonetaryNotionalAmount_019cd0a4-2a95-794d-ac7b-8f8b62974100" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeNonmonetaryNotionalAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019cd0a3-2254-75a0-adfa-4f08d24ac77e" xlink:to="loc_us-gaap_DerivativeNonmonetaryNotionalAmount_019cd0a4-2a95-794d-ac7b-8f8b62974100" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeGainLossOnDerivativeNet_019cd0a4-2a95-7e8b-a9b4-81dd0c199bb9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeGainLossOnDerivativeNet"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019cd0a3-2254-75a0-adfa-4f08d24ac77e" xlink:to="loc_us-gaap_DerivativeGainLossOnDerivativeNet_019cd0a4-2a95-7e8b-a9b4-81dd0c199bb9" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_TranslationAdjustmentForNetInvestmentHedgeIncreaseDecreaseNetOfTax_019cd0a4-2a95-7565-a208-5ae3bf47307a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_TranslationAdjustmentForNetInvestmentHedgeIncreaseDecreaseNetOfTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019cd0a3-2254-75a0-adfa-4f08d24ac77e" xlink:to="loc_us-gaap_TranslationAdjustmentForNetInvestmentHedgeIncreaseDecreaseNetOfTax_019cd0a4-2a95-7565-a208-5ae3bf47307a" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostAfterAllowanceForCreditLossCurrent_019cd0a4-dd51-7771-ae2c-c307c9ca6b13" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostAfterAllowanceForCreditLossCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019cd0a3-2254-75a0-adfa-4f08d24ac77e" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityAmortizedCostAfterAllowanceForCreditLossCurrent_019cd0a4-dd51-7771-ae2c-c307c9ca6b13" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtSecuritiesHeldToMaturityFairValueCurrent_019cd0a4-dd51-7825-8fb5-b5ac2470ba3c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtSecuritiesHeldToMaturityFairValueCurrent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueNetDerivativeAssetLiabilityMeasuredOnRecurringBasisUnobservableInputReconciliationLineItems_019cd0a3-2254-75a0-adfa-4f08d24ac77e" xlink:to="loc_us-gaap_DebtSecuritiesHeldToMaturityFairValueCurrent_019cd0a4-dd51-7825-8fb5-b5ac2470ba3c" xlink:type="arc" order="8"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/FINANCIALINSTRUMENTSANDRISKMANAGEMENTFairValueandCarryingValueofDebtDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#FINANCIALINSTRUMENTSANDRISKMANAGEMENTFairValueandCarryingValueofDebtDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/FINANCIALINSTRUMENTSANDRISKMANAGEMENTFairValueandCarryingValueofDebtDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019b130c-49f5-74e2-a2f3-b83f35fb8ef8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019b130c-49f5-79f4-9d73-fea764b5fa2d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByBalanceSheetGroupingTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019b130c-49f5-74e2-a2f3-b83f35fb8ef8" xlink:to="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019b130c-49f5-79f4-9d73-fea764b5fa2d" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueByMeasurementBasisAxis_019b130c-49f5-7405-9901-bb5fbedc7402" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueByMeasurementBasisAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019b130c-49f5-79f4-9d73-fea764b5fa2d" xlink:to="loc_us-gaap_FairValueByMeasurementBasisAxis_019b130c-49f5-7405-9901-bb5fbedc7402" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019b130c-49f5-7405-9901-bb5fbedc7402_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_019b130c-49f5-7405-9901-bb5fbedc7402" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019b130c-49f5-7405-9901-bb5fbedc7402_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019b130c-49f5-7639-8354-f01cc11345f1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_FairValueDisclosureItemAmountsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_FairValueByMeasurementBasisAxis_019b130c-49f5-7405-9901-bb5fbedc7402" xlink:to="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019b130c-49f5-7639-8354-f01cc11345f1" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019b130c-49f5-75a4-b960-9cb8fd855d25" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PortionAtFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueDisclosureItemAmountsDomain_019b130c-49f5-7639-8354-f01cc11345f1" xlink:to="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019b130c-49f5-75a4-b960-9cb8fd855d25" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_019b130c-49f5-7142-a798-664bd2f2fa84" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EstimateOfFairValueFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019b130c-49f5-75a4-b960-9cb8fd855d25" xlink:to="loc_us-gaap_EstimateOfFairValueFairValueDisclosureMember_019b130c-49f5-7142-a798-664bd2f2fa84" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_019b130c-49f5-7576-95e4-2410712ed225" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CarryingReportedAmountFairValueDisclosureMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_PortionAtFairValueFairValueDisclosureMember_019b130c-49f5-75a4-b960-9cb8fd855d25" xlink:to="loc_us-gaap_CarryingReportedAmountFairValueDisclosureMember_019b130c-49f5-7576-95e4-2410712ed225" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeAxis_019b130c-49f5-7b35-ab49-07c0a9c3dc3b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019b130c-49f5-79f4-9d73-fea764b5fa2d" xlink:to="loc_us-gaap_LongtermDebtTypeAxis_019b130c-49f5-7b35-ab49-07c0a9c3dc3b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019b130c-49f5-7b35-ab49-07c0a9c3dc3b_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019b130c-49f5-7b35-ab49-07c0a9c3dc3b" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019b130c-49f5-7b35-ab49-07c0a9c3dc3b_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LongtermDebtTypeDomain_019b130c-49f5-7197-8302-7123cdd68310" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LongtermDebtTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_LongtermDebtTypeAxis_019b130c-49f5-7b35-ab49-07c0a9c3dc3b" xlink:to="loc_us-gaap_LongtermDebtTypeDomain_019b130c-49f5-7197-8302-7123cdd68310" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevolvingCreditFacilityMember_019b130c-49f5-7fcd-aa6a-968331e75e77" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevolvingCreditFacilityMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019b130c-49f5-7197-8302-7123cdd68310" xlink:to="loc_us-gaap_RevolvingCreditFacilityMember_019b130c-49f5-7fcd-aa6a-968331e75e77" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SeniorNotesMember_019d48f4-34f4-7eab-9dd6-419badf196d3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SeniorNotesMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LongtermDebtTypeDomain_019b130c-49f5-7197-8302-7123cdd68310" xlink:to="loc_us-gaap_SeniorNotesMember_019d48f4-34f4-7eab-9dd6-419badf196d3" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentAxis_019b130c-49f5-7d63-aa1b-f82ab76a4a4e" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_FairValueByBalanceSheetGroupingTable_019b130c-49f5-79f4-9d73-fea764b5fa2d" xlink:to="loc_us-gaap_DebtInstrumentAxis_019b130c-49f5-7d63-aa1b-f82ab76a4a4e" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-7d63-aa1b-f82ab76a4a4e_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DebtInstrumentAxis_019b130c-49f5-7d63-aa1b-f82ab76a4a4e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-7d63-aa1b-f82ab76a4a4e_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-7ad5-b1c9-a48d0746b26d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DebtInstrumentAxis_019b130c-49f5-7d63-aa1b-f82ab76a4a4e" xlink:to="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-7ad5-b1c9-a48d0746b26d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_TermLoanDue2032Member_019b130c-49f5-7922-b472-b54933224e82" xlink:href="vrt-20260331.xsd#vrt_TermLoanDue2032Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-7ad5-b1c9-a48d0746b26d" xlink:to="loc_vrt_TermLoanDue2032Member_019b130c-49f5-7922-b472-b54933224e82" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_SeniorSecuredNotesDue2028Member_019b130c-49f5-7d02-b969-02065dfe23f5" xlink:href="vrt-20260331.xsd#vrt_SeniorSecuredNotesDue2028Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-7ad5-b1c9-a48d0746b26d" xlink:to="loc_vrt_SeniorSecuredNotesDue2028Member_019b130c-49f5-7d02-b969-02065dfe23f5" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_SeniorNotesDue2036Member_019d48ec-696e-7137-b230-986aaadf1c3d" xlink:href="vrt-20260331.xsd#vrt_SeniorNotesDue2036Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-7ad5-b1c9-a48d0746b26d" xlink:to="loc_vrt_SeniorNotesDue2036Member_019d48ec-696e-7137-b230-986aaadf1c3d" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_SeniorNotesDue2046Member_019d48ed-4a11-7954-82aa-8bcc13502d48" xlink:href="vrt-20260331.xsd#vrt_SeniorNotesDue2046Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-7ad5-b1c9-a48d0746b26d" xlink:to="loc_vrt_SeniorNotesDue2046Member_019d48ed-4a11-7954-82aa-8bcc13502d48" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_SeniorNotesDue2056Member_019d48ed-a6d8-7f60-9552-14fd6953765e" xlink:href="vrt-20260331.xsd#vrt_SeniorNotesDue2056Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-7ad5-b1c9-a48d0746b26d" xlink:to="loc_vrt_SeniorNotesDue2056Member_019d48ed-a6d8-7f60-9552-14fd6953765e" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_SeniorNotesDue2066Member_019d48ee-6525-7dd1-a073-8a7e5df0016f" xlink:href="vrt-20260331.xsd#vrt_SeniorNotesDue2066Member"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DebtInstrumentNameDomain_019b130c-49f5-7ad5-b1c9-a48d0746b26d" xlink:to="loc_vrt_SeniorNotesDue2066Member_019d48ee-6525-7dd1-a073-8a7e5df0016f" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentFairValue_019b130c-49f5-7029-ad1d-0a0afd583d01" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentFairValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019b130c-49f5-74e2-a2f3-b83f35fb8ef8" xlink:to="loc_us-gaap_DebtInstrumentFairValue_019b130c-49f5-7029-ad1d-0a0afd583d01" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019d48f4-34f4-712e-ac93-38d1dfe26ebc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DebtInstrumentInterestRateStatedPercentage"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_FairValueBalanceSheetGroupingFinancialStatementCaptionsLineItems_019b130c-49f5-74e2-a2f3-b83f35fb8ef8" xlink:to="loc_us-gaap_DebtInstrumentInterestRateStatedPercentage_019d48f4-34f4-712e-ac93-38d1dfe26ebc" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/ACCUMULATEDOTHERCOMPREHENSIVEINCOMELOSSDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#ACCUMULATEDOTHERCOMPREHENSIVEINCOMELOSSDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/ACCUMULATEDOTHERCOMPREHENSIVEINCOMELOSSDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019b130c-49f5-7427-aab8-920b407ff80d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019b130c-49f5-7388-b4f9-3b6ca0c04a58" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeLossTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019b130c-49f5-7427-aab8-920b407ff80d" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019b130c-49f5-7388-b4f9-3b6ca0c04a58" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementEquityComponentsAxis_019b130c-49f5-7b51-aeee-5368354fd383" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementEquityComponentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019b130c-49f5-7388-b4f9-3b6ca0c04a58" xlink:to="loc_us-gaap_StatementEquityComponentsAxis_019b130c-49f5-7b51-aeee-5368354fd383" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019b130c-49f5-7b51-aeee-5368354fd383_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019b130c-49f5-7b51-aeee-5368354fd383" xlink:to="loc_us-gaap_EquityComponentDomain_019b130c-49f5-7b51-aeee-5368354fd383_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EquityComponentDomain_019b130c-49f5-7ecb-82c2-ce88e3a4b70c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EquityComponentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementEquityComponentsAxis_019b130c-49f5-7b51-aeee-5368354fd383" xlink:to="loc_us-gaap_EquityComponentDomain_019b130c-49f5-7ecb-82c2-ce88e3a4b70c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019b130c-49f5-7e14-8b45-4b81302f4ca6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedOtherComprehensiveIncomeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_EquityComponentDomain_019b130c-49f5-7ecb-82c2-ce88e3a4b70c" xlink:to="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019b130c-49f5-7e14-8b45-4b81302f4ca6" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019b130c-49f5-7285-882e-a99f05ddeeca" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedTranslationAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019b130c-49f5-7e14-8b45-4b81302f4ca6" xlink:to="loc_us-gaap_AccumulatedTranslationAdjustmentMember_019b130c-49f5-7285-882e-a99f05ddeeca" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_019b130c-49f5-759b-b1f4-39d0b98a7f92" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019b130c-49f5-7e14-8b45-4b81302f4ca6" xlink:to="loc_us-gaap_AccumulatedGainLossNetCashFlowHedgeParentMember_019b130c-49f5-759b-b1f4-39d0b98a7f92" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_019b130c-49f5-7174-a88b-d3e19fb06cf9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeMember_019b130c-49f5-7e14-8b45-4b81302f4ca6" xlink:to="loc_us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember_019b130c-49f5-7174-a88b-d3e19fb06cf9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeInstrumentRiskAxis_019b130c-49f5-7b85-a04e-ccd97d780664" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeInstrumentRiskAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossTable_019b130c-49f5-7388-b4f9-3b6ca0c04a58" xlink:to="loc_us-gaap_DerivativeInstrumentRiskAxis_019b130c-49f5-7b85-a04e-ccd97d780664" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019b130c-49f5-7b85-a04e-ccd97d780664_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019b130c-49f5-7b85-a04e-ccd97d780664" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019b130c-49f5-7b85-a04e-ccd97d780664_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DerivativeContractTypeDomain_019b130c-49f5-7059-924a-d8e964590a4f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DerivativeContractTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_DerivativeInstrumentRiskAxis_019b130c-49f5-7b85-a04e-ccd97d780664" xlink:to="loc_us-gaap_DerivativeContractTypeDomain_019b130c-49f5-7059-924a-d8e964590a4f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_InterestRateContractMember_019b130c-49f5-7629-818a-d99fd077e93f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_InterestRateContractMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019b130c-49f5-7059-924a-d8e964590a4f" xlink:to="loc_us-gaap_InterestRateContractMember_019b130c-49f5-7629-818a-d99fd077e93f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignExchangeForwardMember_019b130c-49f5-748d-a608-feed8d0a8594" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignExchangeForwardMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_DerivativeContractTypeDomain_019b130c-49f5-7059-924a-d8e964590a4f" xlink:to="loc_us-gaap_ForeignExchangeForwardMember_019b130c-49f5-748d-a608-feed8d0a8594" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019b130c-49f5-7b52-94a2-5d711597a20d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AOCIAttributableToParentNetOfTaxRollForward"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019b130c-49f5-7427-aab8-920b407ff80d" xlink:to="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019b130c-49f5-7b52-94a2-5d711597a20d" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019b130c-49f5-730f-87a5-8acf44f98987" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019b130c-49f5-7b52-94a2-5d711597a20d" xlink:to="loc_us-gaap_StockholdersEquity_019b130c-49f5-730f-87a5-8acf44f98987" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019b130c-49f5-70a0-8272-cd8c2333f45b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019b130c-49f5-7b52-94a2-5d711597a20d" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent_019b130c-49f5-70a0-8272-cd8c2333f45b" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_019b130c-49f5-70be-8dea-c4b9c856eed9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AOCIAttributableToParentNetOfTaxRollForward_019b130c-49f5-7b52-94a2-5d711597a20d" xlink:to="loc_us-gaap_ReclassificationFromAociCurrentPeriodNetOfTaxAttributableToParent_019b130c-49f5-70be-8dea-c4b9c856eed9" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StockholdersEquity_019b130c-49f5-7fd6-ab2e-ad3288e9139f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StockholdersEquity"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_019b130c-49f5-766a-b704-f6a9f8884d31" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AccumulatedOtherComprehensiveIncomeLossLineItems_019b130c-49f5-7427-aab8-920b407ff80d" xlink:to="loc_us-gaap_OtherComprehensiveIncomeLossTaxPortionAttributableToParent1_019b130c-49f5-766a-b704-f6a9f8884d31" xlink:type="arc" order="1"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/SEGMENTINFORMATIONScheduleofSalesByBusinessSegmentDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#SEGMENTINFORMATIONScheduleofSalesByBusinessSegmentDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/SEGMENTINFORMATIONScheduleofSalesByBusinessSegmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_019b130c-49f5-7ed9-ab06-cf7d5c44a625" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingRevenueReconcilingItemLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_019b130c-49f5-7db3-96c5-eeebe41f6a48" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_019b130c-49f5-7ed9-ab06-cf7d5c44a625" xlink:to="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_019b130c-49f5-7db3-96c5-eeebe41f6a48" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019b130c-49f5-747a-9aa1-ac9f0db94e99" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_019b130c-49f5-7db3-96c5-eeebe41f6a48" xlink:to="loc_srt_ConsolidationItemsAxis_019b130c-49f5-747a-9aa1-ac9f0db94e99" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019b130c-49f5-747a-9aa1-ac9f0db94e99_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019b130c-49f5-747a-9aa1-ac9f0db94e99" xlink:to="loc_srt_ConsolidationItemsDomain_019b130c-49f5-747a-9aa1-ac9f0db94e99_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019b130c-49f5-7ba1-b37f-91b39c01ec51" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019b130c-49f5-747a-9aa1-ac9f0db94e99" xlink:to="loc_srt_ConsolidationItemsDomain_019b130c-49f5-7ba1-b37f-91b39c01ec51" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_019b130c-49f5-7885-b9ae-68e012ed2c05" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019b130c-49f5-7ba1-b37f-91b39c01ec51" xlink:to="loc_us-gaap_OperatingSegmentsMember_019b130c-49f5-7885-b9ae-68e012ed2c05" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IntersegmentEliminationMember_019b130c-49f5-77cf-8214-bc0534b3a36b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IntersegmentEliminationMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019b130c-49f5-7ba1-b37f-91b39c01ec51" xlink:to="loc_us-gaap_IntersegmentEliminationMember_019b130c-49f5-77cf-8214-bc0534b3a36b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_CorporateAndReconcilingItemsMember_019b130c-49f5-7d71-a353-bedb4f52df01" xlink:href="vrt-20260331.xsd#vrt_CorporateAndReconcilingItemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019b130c-49f5-7ba1-b37f-91b39c01ec51" xlink:to="loc_vrt_CorporateAndReconcilingItemsMember_019b130c-49f5-7d71-a353-bedb4f52df01" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_CorporateReconcilingItemsAndEliminationsMember_019b130c-49f5-7572-b1a6-878c05cf6af3" xlink:href="vrt-20260331.xsd#vrt_CorporateReconcilingItemsAndEliminationsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019b130c-49f5-7ba1-b37f-91b39c01ec51" xlink:to="loc_vrt_CorporateReconcilingItemsAndEliminationsMember_019b130c-49f5-7572-b1a6-878c05cf6af3" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaterialReconcilingItemsMember_019b130c-49f5-7176-aae1-34d9c9031788" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MaterialReconcilingItemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019b130c-49f5-7ba1-b37f-91b39c01ec51" xlink:to="loc_us-gaap_MaterialReconcilingItemsMember_019b130c-49f5-7176-aae1-34d9c9031788" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-49f5-7887-98f0-a44b0aeab164" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_019b130c-49f5-7db3-96c5-eeebe41f6a48" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-49f5-7887-98f0-a44b0aeab164" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019b130c-49f5-7887-98f0-a44b0aeab164_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-49f5-7887-98f0-a44b0aeab164" xlink:to="loc_us-gaap_SegmentDomain_019b130c-49f5-7887-98f0-a44b0aeab164_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019b130c-49f5-7f20-8cbe-fda5afef00fa" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-49f5-7887-98f0-a44b0aeab164" xlink:to="loc_us-gaap_SegmentDomain_019b130c-49f5-7f20-8cbe-fda5afef00fa" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_AmericasSegmentMember_019b130c-49f5-7a84-a6cc-1b0f6311532e" xlink:href="vrt-20260331.xsd#vrt_AmericasSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b130c-49f5-7f20-8cbe-fda5afef00fa" xlink:to="loc_vrt_AmericasSegmentMember_019b130c-49f5-7a84-a6cc-1b0f6311532e" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_AsiaPacificSegmentMember_019b130c-49f5-7dc1-837d-9381306c575b" xlink:href="vrt-20260331.xsd#vrt_AsiaPacificSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b130c-49f5-7f20-8cbe-fda5afef00fa" xlink:to="loc_vrt_AsiaPacificSegmentMember_019b130c-49f5-7dc1-837d-9381306c575b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_EMEASegmentMember_019b130c-49f5-778a-9767-eec06c180d83" xlink:href="vrt-20260331.xsd#vrt_EMEASegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b130c-49f5-7f20-8cbe-fda5afef00fa" xlink:to="loc_vrt_EMEASegmentMember_019b130c-49f5-778a-9767-eec06c180d83" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019b130c-49f5-701f-8653-3cd8b8819e0a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_019b130c-49f5-7ed9-ab06-cf7d5c44a625" xlink:to="loc_us-gaap_RevenueFromContractWithCustomerExcludingAssessedTax_019b130c-49f5-701f-8653-3cd8b8819e0a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CostsAndExpenses_019b130c-49f5-77de-beaf-5edcfc412da8" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CostsAndExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_019b130c-49f5-7ed9-ab06-cf7d5c44a625" xlink:to="loc_us-gaap_CostsAndExpenses_019b130c-49f5-77de-beaf-5edcfc412da8" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019b130c-49f5-75bc-8f63-82bd406bd478" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SellingGeneralAndAdministrativeExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_019b130c-49f5-7ed9-ab06-cf7d5c44a625" xlink:to="loc_us-gaap_SellingGeneralAndAdministrativeExpense_019b130c-49f5-75bc-8f63-82bd406bd478" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ResearchAndDevelopmentExpense_019b130c-49f5-795b-a62a-87f9d77e36c7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ResearchAndDevelopmentExpense"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_019b130c-49f5-7ed9-ab06-cf7d5c44a625" xlink:to="loc_us-gaap_ResearchAndDevelopmentExpense_019b130c-49f5-795b-a62a-87f9d77e36c7" xlink:type="arc" order="3"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_InformationTechnologyExpenses_019b130c-49f5-7427-b60a-59857479e68c" xlink:href="vrt-20260331.xsd#vrt_InformationTechnologyExpenses"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_019b130c-49f5-7ed9-ab06-cf7d5c44a625" xlink:to="loc_vrt_InformationTechnologyExpenses_019b130c-49f5-7427-b60a-59857479e68c" xlink:type="arc" order="4"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_RestructuringCharges_019b130c-49f5-7319-a465-4c42487ddd9d" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_RestructuringCharges"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_019b130c-49f5-7ed9-ab06-cf7d5c44a625" xlink:to="loc_us-gaap_RestructuringCharges_019b130c-49f5-7319-a465-4c42487ddd9d" xlink:type="arc" order="5"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingOtherItemAmount_019b130c-49f5-738f-8400-08f594846ab6" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingOtherItemAmount"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_019b130c-49f5-7ed9-ab06-cf7d5c44a625" xlink:to="loc_us-gaap_SegmentReportingOtherItemAmount_019b130c-49f5-738f-8400-08f594846ab6" xlink:type="arc" order="6"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingIncomeLoss_019b130c-49f5-78de-b5c1-9cdb98a416dc" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingIncomeLoss"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_019b130c-49f5-7ed9-ab06-cf7d5c44a625" xlink:to="loc_us-gaap_OperatingIncomeLoss_019b130c-49f5-78de-b5c1-9cdb98a416dc" xlink:type="arc" order="7"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_019b130c-49f5-7d7d-b166-fe30b8ab1aa3" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ForeignCurrencyTransactionGainLossBeforeTax"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_019b130c-49f5-7ed9-ab06-cf7d5c44a625" xlink:to="loc_us-gaap_ForeignCurrencyTransactionGainLossBeforeTax_019b130c-49f5-7d7d-b166-fe30b8ab1aa3" xlink:type="arc" order="8"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019b130c-49f5-7975-be61-b95af7cb62bb" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_019b130c-49f5-7ed9-ab06-cf7d5c44a625" xlink:to="loc_us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest_019b130c-49f5-7975-be61-b95af7cb62bb" xlink:type="arc" order="9"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AmortizationOfIntangibleAssets_019b130c-49f5-787c-a86b-354c5660e466" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AmortizationOfIntangibleAssets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_019b130c-49f5-7ed9-ab06-cf7d5c44a625" xlink:to="loc_us-gaap_AmortizationOfIntangibleAssets_019b130c-49f5-787c-a86b-354c5660e466" xlink:type="arc" order="10"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/SEGMENTINFORMATIONScheduleofTotalAssetsbySegmentDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#SEGMENTINFORMATIONScheduleofTotalAssetsbySegmentDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/SEGMENTINFORMATIONScheduleofTotalAssetsbySegmentDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_019b130c-49f5-72b7-87ad-b60879dbc205" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingAssetReconcilingItemLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_019b130c-49f5-7ea8-a943-8a85c8a53fef" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_019b130c-49f5-72b7-87ad-b60879dbc205" xlink:to="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_019b130c-49f5-7ea8-a943-8a85c8a53fef" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019b130c-49f5-76d7-b18f-fda2bb36f4e2" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_019b130c-49f5-7ea8-a943-8a85c8a53fef" xlink:to="loc_srt_ConsolidationItemsAxis_019b130c-49f5-76d7-b18f-fda2bb36f4e2" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019b130c-49f5-76d7-b18f-fda2bb36f4e2_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019b130c-49f5-76d7-b18f-fda2bb36f4e2" xlink:to="loc_srt_ConsolidationItemsDomain_019b130c-49f5-76d7-b18f-fda2bb36f4e2_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019b130c-49f5-70b0-bee3-5d82ed3df352" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019b130c-49f5-76d7-b18f-fda2bb36f4e2" xlink:to="loc_srt_ConsolidationItemsDomain_019b130c-49f5-70b0-bee3-5d82ed3df352" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_019b130c-49f5-7c9d-9cec-6f890ec273a2" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019b130c-49f5-70b0-bee3-5d82ed3df352" xlink:to="loc_us-gaap_OperatingSegmentsMember_019b130c-49f5-7c9d-9cec-6f890ec273a2" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_CorporateNonSegmentMember_019b130c-49f5-794d-8e3d-6502d2aa109c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_CorporateNonSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019b130c-49f5-70b0-bee3-5d82ed3df352" xlink:to="loc_us-gaap_CorporateNonSegmentMember_019b130c-49f5-794d-8e3d-6502d2aa109c" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-49f5-73c9-aae5-3dc364dbae84" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfAssetsFromSegmentToConsolidatedTable_019b130c-49f5-7ea8-a943-8a85c8a53fef" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-49f5-73c9-aae5-3dc364dbae84" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019b130c-49f5-73c9-aae5-3dc364dbae84_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-49f5-73c9-aae5-3dc364dbae84" xlink:to="loc_us-gaap_SegmentDomain_019b130c-49f5-73c9-aae5-3dc364dbae84_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019b130c-49f5-7263-adf1-4f90930fdfb0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-49f5-73c9-aae5-3dc364dbae84" xlink:to="loc_us-gaap_SegmentDomain_019b130c-49f5-7263-adf1-4f90930fdfb0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_AmericasSegmentMember_019b130c-49f5-7853-9c64-399d07caf9b5" xlink:href="vrt-20260331.xsd#vrt_AmericasSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b130c-49f5-7263-adf1-4f90930fdfb0" xlink:to="loc_vrt_AmericasSegmentMember_019b130c-49f5-7853-9c64-399d07caf9b5" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_AsiaPacificSegmentMember_019b130c-49f5-7bd5-b996-23a23d5a4f24" xlink:href="vrt-20260331.xsd#vrt_AsiaPacificSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b130c-49f5-7263-adf1-4f90930fdfb0" xlink:to="loc_vrt_AsiaPacificSegmentMember_019b130c-49f5-7bd5-b996-23a23d5a4f24" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_EMEASegmentMember_019b130c-49f5-737e-ad6d-9b0519f90933" xlink:href="vrt-20260331.xsd#vrt_EMEASegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b130c-49f5-7263-adf1-4f90930fdfb0" xlink:to="loc_vrt_EMEASegmentMember_019b130c-49f5-737e-ad6d-9b0519f90933" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_Assets_019b130c-49f5-7363-a076-b28882b1b6d9" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_Assets"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingAssetReconcilingItemLineItems_019b130c-49f5-72b7-87ad-b60879dbc205" xlink:to="loc_us-gaap_Assets_019b130c-49f5-7363-a076-b28882b1b6d9" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/SEGMENTINFORMATIONScheduleofDepreciationandAmortizationDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#SEGMENTINFORMATIONScheduleofDepreciationandAmortizationDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/SEGMENTINFORMATIONScheduleofDepreciationandAmortizationDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_019b130c-49f5-7412-97a8-f310e7482948" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingRevenueReconcilingItemLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_019b130c-49f5-7c0a-8250-370d71d53ea7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_019b130c-49f5-7412-97a8-f310e7482948" xlink:to="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_019b130c-49f5-7c0a-8250-370d71d53ea7" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019b130c-49f5-7b6f-84fb-cbd10eb4e6cb" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_019b130c-49f5-7c0a-8250-370d71d53ea7" xlink:to="loc_srt_ConsolidationItemsAxis_019b130c-49f5-7b6f-84fb-cbd10eb4e6cb" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019b130c-49f5-7b6f-84fb-cbd10eb4e6cb_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019b130c-49f5-7b6f-84fb-cbd10eb4e6cb" xlink:to="loc_srt_ConsolidationItemsDomain_019b130c-49f5-7b6f-84fb-cbd10eb4e6cb_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019b130c-49f5-757d-88e1-81ace1aebd64" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019b130c-49f5-7b6f-84fb-cbd10eb4e6cb" xlink:to="loc_srt_ConsolidationItemsDomain_019b130c-49f5-757d-88e1-81ace1aebd64" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_019b130c-49f5-7fd4-8d7a-3660a65b3a2a" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019b130c-49f5-757d-88e1-81ace1aebd64" xlink:to="loc_us-gaap_OperatingSegmentsMember_019b130c-49f5-7fd4-8d7a-3660a65b3a2a" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaterialReconcilingItemsMember_019b130c-49f5-756b-99e8-4e6d9a48db01" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MaterialReconcilingItemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019b130c-49f5-757d-88e1-81ace1aebd64" xlink:to="loc_us-gaap_MaterialReconcilingItemsMember_019b130c-49f5-756b-99e8-4e6d9a48db01" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-49f5-7272-8c6a-8528412ec2ce" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_019b130c-49f5-7c0a-8250-370d71d53ea7" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-49f5-7272-8c6a-8528412ec2ce" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019b130c-49f5-7272-8c6a-8528412ec2ce_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-49f5-7272-8c6a-8528412ec2ce" xlink:to="loc_us-gaap_SegmentDomain_019b130c-49f5-7272-8c6a-8528412ec2ce_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019b130c-49f5-7696-bb25-ef102ed09126" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-49f5-7272-8c6a-8528412ec2ce" xlink:to="loc_us-gaap_SegmentDomain_019b130c-49f5-7696-bb25-ef102ed09126" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_AmericasSegmentMember_019b130c-49f5-7500-977d-7e7437b9c657" xlink:href="vrt-20260331.xsd#vrt_AmericasSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b130c-49f5-7696-bb25-ef102ed09126" xlink:to="loc_vrt_AmericasSegmentMember_019b130c-49f5-7500-977d-7e7437b9c657" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_AsiaPacificSegmentMember_019b130c-49f5-7dda-9f25-e591de57f27f" xlink:href="vrt-20260331.xsd#vrt_AsiaPacificSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b130c-49f5-7696-bb25-ef102ed09126" xlink:to="loc_vrt_AsiaPacificSegmentMember_019b130c-49f5-7dda-9f25-e591de57f27f" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_EMEASegmentMember_019b130c-49f5-734d-ad70-fce5b9f4eeca" xlink:href="vrt-20260331.xsd#vrt_EMEASegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b130c-49f5-7696-bb25-ef102ed09126" xlink:to="loc_vrt_EMEASegmentMember_019b130c-49f5-734d-ad70-fce5b9f4eeca" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_DepreciationDepletionAndAmortization_019b130c-49f5-7169-bcf5-bcae892a1d06" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_DepreciationDepletionAndAmortization"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_019b130c-49f5-7412-97a8-f310e7482948" xlink:to="loc_us-gaap_DepreciationDepletionAndAmortization_019b130c-49f5-7169-bcf5-bcae892a1d06" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/SEGMENTINFORMATIONScheduleofCapitalExpendituresDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#SEGMENTINFORMATIONScheduleofCapitalExpendituresDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/SEGMENTINFORMATIONScheduleofCapitalExpendituresDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_019b130c-49f5-76dd-8b50-6b1d72098675" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentReportingRevenueReconcilingItemLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_019b130c-49f5-758e-9bcb-812e6f76bb86" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_019b130c-49f5-76dd-8b50-6b1d72098675" xlink:to="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_019b130c-49f5-758e-9bcb-812e6f76bb86" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsAxis_019b130c-49f5-7515-99d5-853709c3818d" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_019b130c-49f5-758e-9bcb-812e6f76bb86" xlink:to="loc_srt_ConsolidationItemsAxis_019b130c-49f5-7515-99d5-853709c3818d" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019b130c-49f5-7515-99d5-853709c3818d_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_ConsolidationItemsAxis_019b130c-49f5-7515-99d5-853709c3818d" xlink:to="loc_srt_ConsolidationItemsDomain_019b130c-49f5-7515-99d5-853709c3818d_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_ConsolidationItemsDomain_019b130c-49f5-7f55-a333-9bedf86e7fba" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_ConsolidationItemsDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_ConsolidationItemsAxis_019b130c-49f5-7515-99d5-853709c3818d" xlink:to="loc_srt_ConsolidationItemsDomain_019b130c-49f5-7f55-a333-9bedf86e7fba" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_OperatingSegmentsMember_019b130c-49f5-7596-afab-b1ce6c91318c" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_OperatingSegmentsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019b130c-49f5-7f55-a333-9bedf86e7fba" xlink:to="loc_us-gaap_OperatingSegmentsMember_019b130c-49f5-7596-afab-b1ce6c91318c" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_MaterialReconcilingItemsMember_019b130c-49f5-7253-812b-a2f1601c7e5b" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_MaterialReconcilingItemsMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_ConsolidationItemsDomain_019b130c-49f5-7f55-a333-9bedf86e7fba" xlink:to="loc_us-gaap_MaterialReconcilingItemsMember_019b130c-49f5-7253-812b-a2f1601c7e5b" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-49f5-7da7-8a48-42d710ef14f1" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_StatementBusinessSegmentsAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ReconciliationOfRevenueFromSegmentsToConsolidatedTable_019b130c-49f5-758e-9bcb-812e6f76bb86" xlink:to="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-49f5-7da7-8a48-42d710ef14f1" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019b130c-49f5-7da7-8a48-42d710ef14f1_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-49f5-7da7-8a48-42d710ef14f1" xlink:to="loc_us-gaap_SegmentDomain_019b130c-49f5-7da7-8a48-42d710ef14f1_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_SegmentDomain_019b130c-49f5-7075-9649-a7e39a6fa5e0" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_SegmentDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_StatementBusinessSegmentsAxis_019b130c-49f5-7da7-8a48-42d710ef14f1" xlink:to="loc_us-gaap_SegmentDomain_019b130c-49f5-7075-9649-a7e39a6fa5e0" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_AmericasSegmentMember_019b130c-49f5-7af1-aac0-f51344aebc40" xlink:href="vrt-20260331.xsd#vrt_AmericasSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b130c-49f5-7075-9649-a7e39a6fa5e0" xlink:to="loc_vrt_AmericasSegmentMember_019b130c-49f5-7af1-aac0-f51344aebc40" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_AsiaPacificSegmentMember_019b130c-49f5-7287-a55e-f7399e6f887a" xlink:href="vrt-20260331.xsd#vrt_AsiaPacificSegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b130c-49f5-7075-9649-a7e39a6fa5e0" xlink:to="loc_vrt_AsiaPacificSegmentMember_019b130c-49f5-7287-a55e-f7399e6f887a" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_EMEASegmentMember_019b130c-49f5-7fb6-a579-2f6b1ccfd5a8" xlink:href="vrt-20260331.xsd#vrt_EMEASegmentMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentDomain_019b130c-49f5-7075-9649-a7e39a6fa5e0" xlink:to="loc_vrt_EMEASegmentMember_019b130c-49f5-7fb6-a579-2f6b1ccfd5a8" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_019b130c-49f5-7636-9282-08177386e66f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentsToAcquirePropertyPlantAndEquipment"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_SegmentReportingRevenueReconcilingItemLineItems_019b130c-49f5-76dd-8b50-6b1d72098675" xlink:to="loc_us-gaap_PaymentsToAcquirePropertyPlantAndEquipment_019b130c-49f5-7636-9282-08177386e66f" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/EARNINGSLOSSPERSHARENarrativeDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#EARNINGSLOSSPERSHARENarrativeDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/EARNINGSLOSSPERSHARENarrativeDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019b130c-49f5-7d9a-91df-c84228628300" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019b130c-49f5-74da-b49f-57dc12968012" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019b130c-49f5-7d9a-91df-c84228628300" xlink:to="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019b130c-49f5-74da-b49f-57dc12968012" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019b130c-49f5-7932-a881-36e4712faf33" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_ScheduleOfAntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareTable_019b130c-49f5-74da-b49f-57dc12968012" xlink:to="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019b130c-49f5-7932-a881-36e4712faf33" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019b130c-49f5-7932-a881-36e4712faf33_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019b130c-49f5-7932-a881-36e4712faf33" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019b130c-49f5-7932-a881-36e4712faf33_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019b130c-49f5-746a-ade4-3cfb2c7beb91" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_AntidilutiveSecuritiesNameDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareByAntidilutiveSecuritiesAxis_019b130c-49f5-7932-a881-36e4712faf33" xlink:to="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019b130c-49f5-746a-ade4-3cfb2c7beb91" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_EmployeeStockOptionMember_019b130c-49f5-724e-b753-212a9550963f" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_EmployeeStockOptionMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesNameDomain_019b130c-49f5-746a-ade4-3cfb2c7beb91" xlink:to="loc_us-gaap_EmployeeStockOptionMember_019b130c-49f5-724e-b753-212a9550963f" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_019b130c-49f5-70fb-8274-6481a9962f77" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems_019b130c-49f5-7d9a-91df-c84228628300" xlink:to="loc_us-gaap_IncrementalCommonSharesAttributableToShareBasedPaymentArrangements_019b130c-49f5-70fb-8274-6481a9962f77" xlink:type="arc" order="0"/>
  </link:definitionLink>
  <link:roleRef roleURI="http://www.vertiv.com/role/COMMITMENTSANDCONTINGENCIESDetails" xlink:type="simple" xlink:href="vrt-20260331.xsd#COMMITMENTSANDCONTINGENCIESDetails"/>
  <link:definitionLink xlink:role="http://www.vertiv.com/role/COMMITMENTSANDCONTINGENCIESDetails" xlink:type="extended">
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesLineItems_019b130c-49f5-7cb8-9509-06ff18d9c770" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesLineItems"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingenciesTable_019b130c-49f5-76b4-b150-9b64005a7a46" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingenciesTable"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/all" xlink:from="loc_us-gaap_LossContingenciesLineItems_019b130c-49f5-7cb8-9509-06ff18d9c770" xlink:to="loc_us-gaap_LossContingenciesTable_019b130c-49f5-76b4-b150-9b64005a7a46" xlink:type="arc" order="1" xbrldt:closed="true" xbrldt:contextElement="segment"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseAxis_019b130c-49f5-7620-b905-751c70e700dd" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019b130c-49f5-76b4-b150-9b64005a7a46" xlink:to="loc_srt_LitigationCaseAxis_019b130c-49f5-7620-b905-751c70e700dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019b130c-49f5-7620-b905-751c70e700dd_default" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_srt_LitigationCaseAxis_019b130c-49f5-7620-b905-751c70e700dd" xlink:to="loc_srt_LitigationCaseTypeDomain_019b130c-49f5-7620-b905-751c70e700dd_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_srt_LitigationCaseTypeDomain_019b130c-49f5-7d4c-8dfb-2a670a3239dd" xlink:href="https://xbrl.fasb.org/srt/2025/elts/srt-2025.xsd#srt_LitigationCaseTypeDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_srt_LitigationCaseAxis_019b130c-49f5-7620-b905-751c70e700dd" xlink:to="loc_srt_LitigationCaseTypeDomain_019b130c-49f5-7d4c-8dfb-2a670a3239dd" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_vrt_SullivanVJohnsonEtAlMember_019b130c-49f5-7fff-a4b4-40bae444554b" xlink:href="vrt-20260331.xsd#vrt_SullivanVJohnsonEtAlMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_srt_LitigationCaseTypeDomain_019b130c-49f5-7d4c-8dfb-2a670a3239dd" xlink:to="loc_vrt_SullivanVJohnsonEtAlMember_019b130c-49f5-7fff-a4b4-40bae444554b" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsByNatureAxis_019b130c-49f5-7c5c-af65-2664fd718af7" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteeObligationsByNatureAxis"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/hypercube-dimension" xlink:from="loc_us-gaap_LossContingenciesTable_019b130c-49f5-76b4-b150-9b64005a7a46" xlink:to="loc_us-gaap_GuaranteeObligationsByNatureAxis_019b130c-49f5-7c5c-af65-2664fd718af7" xlink:type="arc" order="2"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_019b130c-49f5-7c5c-af65-2664fd718af7_default" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteeObligationsNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-default" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_019b130c-49f5-7c5c-af65-2664fd718af7" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_019b130c-49f5-7c5c-af65-2664fd718af7_default" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsNatureDomain_019b130c-49f5-7149-9656-ebd0439f4916" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteeObligationsNatureDomain"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/dimension-domain" xlink:from="loc_us-gaap_GuaranteeObligationsByNatureAxis_019b130c-49f5-7c5c-af65-2664fd718af7" xlink:to="loc_us-gaap_GuaranteeObligationsNatureDomain_019b130c-49f5-7149-9656-ebd0439f4916" xlink:type="arc" order="1"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_PaymentGuaranteeMember_019b130c-49f5-7f94-b3d8-0d2ad227eb92" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_PaymentGuaranteeMember"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_GuaranteeObligationsNatureDomain_019b130c-49f5-7149-9656-ebd0439f4916" xlink:to="loc_us-gaap_PaymentGuaranteeMember_019b130c-49f5-7f94-b3d8-0d2ad227eb92" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_LossContingencyNumberOfPlaintiffs_019b130c-49f5-79c2-8e3d-4fe0042aabc4" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_LossContingencyNumberOfPlaintiffs"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019b130c-49f5-7cb8-9509-06ff18d9c770" xlink:to="loc_us-gaap_LossContingencyNumberOfPlaintiffs_019b130c-49f5-79c2-8e3d-4fe0042aabc4" xlink:type="arc" order="0"/>
    <link:loc xlink:type="locator" xlink:label="loc_us-gaap_GuaranteeObligationsCurrentCarryingValue_019b130c-49f5-78f9-81fa-fd3ed2cf71db" xlink:href="https://xbrl.fasb.org/us-gaap/2025/elts/us-gaap-2025.xsd#us-gaap_GuaranteeObligationsCurrentCarryingValue"/>
    <link:definitionArc xlink:arcrole="http://xbrl.org/int/dim/arcrole/domain-member" xlink:from="loc_us-gaap_LossContingenciesLineItems_019b130c-49f5-7cb8-9509-06ff18d9c770" xlink:to="loc_us-gaap_GuaranteeObligationsCurrentCarryingValue_019b130c-49f5-78f9-81fa-fd3ed2cf71db" xlink:type="arc" order="1"/>
  </link:definitionLink>
</link:linkbase>
