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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2020-03-19</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001705110</issuerCik>
        <issuerName>ANGI Homeservices Inc.</issuerName>
        <issuerTradingSymbol>ANGI</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001781028</rptOwnerCik>
            <rptOwnerName>Hanrahan Oisin</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O ANGI HOMESERVICES INC.</rptOwnerStreet1>
            <rptOwnerStreet2>3601 WALNUT STREET, SUITE 700</rptOwnerStreet2>
            <rptOwnerCity>DENVER</rptOwnerCity>
            <rptOwnerState>CO</rptOwnerState>
            <rptOwnerZipCode>80205</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>CPO</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable></nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
                <footnoteId id="F1"/>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2020-03-19</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>A</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>738552</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2023-02-15</value>
                <footnoteId id="F1"/>
            </exerciseDate>
            <expirationDate>
                <value>2023-02-15</value>
                <footnoteId id="F1"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Class A Common Stock, par value $0.001</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>738552</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>738552</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Represents performance-based restricted stock units (&quot;PSUs&quot;), the vesting of which is subject to: (i) the Reporting Person's continuous service with ANGI through February 15, 2023 and (ii) the satisfaction of certain performance conditions related to the market price of ANGI Class A Common Stock (the &quot;Market Price Test&quot;) and ANGI 2022 revenue and Adjusted EBITDA (the &quot;Results Test&quot;). From zero to 200% of the number of PSUs reported in Table II of this form can potentially vest, with the exact number of PSUs so vesting to be the greater of the number determined by applying the Market Price Test and the Results Test. In the case of the Market Price Test, 0%, 50%, 100%, 150% and 200% of the PSUs will vest if the price of ANGI Class A Common Stock is less than $6.77, $6.77, $9.00, $11.24 and $13.54, respectively (with linear interpolation applied for stock prices between the levels previously indicated).</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>Tanya M. Stanich as Attorney-in-Fact for Oisin Hanrahan</signatureName>
        <signatureDate>2020-03-23</signatureDate>
    </ownerSignature>
</ownershipDocument>
