<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-11-20</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001398659</issuerCik>
        <issuerName>Genpact LTD</issuerName>
        <issuerTradingSymbol>G</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000936828</rptOwnerCik>
            <rptOwnerName>GIC Private Ltd</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>168 ROBINSON ROAD #37-01</rptOwnerStreet1>
            <rptOwnerStreet2>CAPITAL TOWER</rptOwnerStreet2>
            <rptOwnerCity>SINGAPORE</rptOwnerCity>
            <rptOwnerState>U0</rptOwnerState>
            <rptOwnerZipCode>068912</rptOwnerZipCode>
            <rptOwnerStateDescription>SINGAPORE</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>See Footnotes</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001561359</rptOwnerCik>
            <rptOwnerName>Twickenham Investment Private Ltd</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>168 ROBINSON ROAD #37-01</rptOwnerStreet1>
            <rptOwnerStreet2>CAPITAL TOWER</rptOwnerStreet2>
            <rptOwnerCity>SINGAPORE</rptOwnerCity>
            <rptOwnerState>U0</rptOwnerState>
            <rptOwnerZipCode>068912</rptOwnerZipCode>
            <rptOwnerStateDescription>SINGAPORE</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>See Footnotes</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001296212</rptOwnerCik>
            <rptOwnerName>GIC Special Investments Pte Ltd</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>168 ROBINSON ROAD #37-01</rptOwnerStreet1>
            <rptOwnerStreet2>CAPITAL TOWER</rptOwnerStreet2>
            <rptOwnerCity>SINGAPORE</rptOwnerCity>
            <rptOwnerState>U0</rptOwnerState>
            <rptOwnerZipCode>068912</rptOwnerZipCode>
            <rptOwnerStateDescription>SINGAPORE</rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>1</isOther>
            <otherText>See Footnotes</otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares, par value $0.01 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2017-11-20</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1499806</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>30.26</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>7392645</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                    <footnoteId id="F6"/>
                    <footnoteId id="F7"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                    <footnoteId id="F6"/>
                    <footnoteId id="F7"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See footnotes</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                    <footnoteId id="F6"/>
                    <footnoteId id="F7"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">This report is filed jointly by GIC Private Limited (&quot;GIC&quot;), GIC Special Investments Pte. Ltd. (&quot;GICSI&quot;) and Twickenham Investment Private Limited (&quot;Twickenham&quot;, and together with GIC and GICSI, the &quot;Reporting Persons&quot;).</footnote>
        <footnote id="F2">On November 14, 2017, Twickenham entered into an underwriting agreement (the &quot;Underwriting Agreement&quot;) with the Issuer, J.P. Morgan Securities LLC (the &quot;Underwriter&quot;) and various other selling shareholders named therein, pursuant to which the Underwriter agreed to purchase an aggregate of 1,499,806 common shares of the Issuer from Twickenham at a price of $30.26 per share. This transaction closed on November 20, 2017.</footnote>
        <footnote id="F3">GIC is the direct owner of 230,975 common shares of the Issuer and Twickenham is the direct owner of 7,161,670 common shares of the Issuer. Twickenham is controlled and managed by GICSI, which is in turn wholly-owned by GIC. GICSI and GIC may be deemed to share voting and dispositive power with respect to the 7,161,670 common shares of the Issuer directly owned by Twickenham. No individual has beneficial ownership over the common shares of the Issuer beneficially owned by the Reporting Persons. Each of the Reporting Persons disclaims beneficial ownership of these securities, except to the extent of its pecuniary interest therein.</footnote>
        <footnote id="F4">On October 25, 2012, (i) Twickenham, Glory Investments A Limited (&quot;Glory A&quot;), Glory Investments B Limited (&quot;Glory B&quot;), Glory Investments IV Limited (&quot;Glory IV&quot;), Glory Investments IV-B Limited (&quot;GloryIV-B&quot;), RGIP, LLC (&quot;RGIP&quot; and collectively with Glory A, Glory B, Glory IV, Glory IV-B and Twickenham, the &quot;Genpact Investors&quot;), Glory Investments TA IV Limited (&quot;Glory TA&quot;) and the Issuer entered into an amended and restated shareholders agreement (the &quot;Shareholders Agreement&quot;), and (ii) the Genpact Investors and Glory TA entered into an investor agreement (&quot;Investor Agreement&quot;).</footnote>
        <footnote id="F5">Pursuant to the Investor Agreement, the Genpact Investors irrevocably appointed a single Investors' Representative (as defined in the Investor Agreement) as its sole and exclusive agent and proxy and true and lawful attorney-in-fact to take certain actions on behalf of each of the Genpact Investors relating to the voting and disposition of the Common Shares and the exercise of certain rights under the Shareholders Agreement, including, (i) voting and dispositive authority with respect to all Common Shares held directly or indirectly by the Genpact Investors, (ii) power to exercise registration rights under the Shareholders Agreement, (iii) the exclusive power to designate all individuals with respect to which the Genpact Investors may, by rights granted to them under the Shareholders Agreement, nominate to the Issuer's board of directors (including designation of such individuals' respective replacements), and</footnote>
        <footnote id="F6">(Continued From Footnote 5) (iv) power and authority to elect to subscribe for new equity securities of Genpact on behalf of the Genpact Investors in connection with the exercise of any pre-emptive rights of the Genpact Investors under the Shareholders Agreement.</footnote>
        <footnote id="F7">As a result of the Shareholders Agreement and Investor Agreement, each of the Genpact Investors and Glory TA may be deemed to beneficially own the Common Shares held by Twickenham, Glory A, Glory B, Glory IV and Glory IV-B. Twickenham disclaims beneficial ownership of such securities except to the extent of its pecuniary interest therein.</footnote>
    </footnotes>

    <remarks>MEMBER OF 10% OWNER GROUP (1)(2)(3)(4)(5)(6)(7)</remarks>

    <ownerSignature>
        <signatureName>/s/ Jimmy Teo, Jimmy Teo, Senior Vice President of GIC Private Limited</signatureName>
        <signatureDate>2017-11-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Celine Loh, Celine Loh, Senior Vice President of GIC Private Limited</signatureName>
        <signatureDate>2017-11-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Deanna Ong, Deanna Ong, Director of GIC Special Investments Pte. Ltd.</signatureName>
        <signatureDate>2017-11-20</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Matthew Lim, Matthew Lim, Director of Twickenham Investment Private Limited</signatureName>
        <signatureDate>2017-11-20</signatureDate>
    </ownerSignature>
</ownershipDocument>
