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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2016-10-05</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001579471</issuerCik>
        <issuerName>Colony Starwood Homes</issuerName>
        <issuerTradingSymbol>SFR</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001076343</rptOwnerCik>
            <rptOwnerName>BARRACK THOMAS JR</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>515 SOUTH FLOWER</rptOwnerStreet1>
            <rptOwnerStreet2>44TH FLOOR</rptOwnerStreet2>
            <rptOwnerCity>LOS ANGELES</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>90071</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Shares, per value $0.01 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2016-10-05</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>J</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
                <footnoteId id="F2"/>
                <footnoteId id="F3"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>27575055</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8102004</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>By controlled entities</value>
                    <footnoteId id="F4"/>
                    <footnoteId id="F5"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">On October 5, 2016, each of Series X Holdco, LLC, a Delaware limited liability company (&quot;Series X&quot;), and Manager Holdco, LLC, a Delaware limited liability company (&quot;Manager Holdco&quot;), transferred all of its Common Shares, par value $0.01 per share, of the Issuer (the &quot;Shares&quot;) to all its members on a pro rata basis and without consideration pursuant to the terms of its limited liability company agreement. Subsequently on October 5, 2016, in a series of transfers, certain entities controlled by the Reporting Person, each with a direct or indirect interest in Series X or Manager Holdco, transferred all of its Shares to all of its members or limited partners, as applicable, on a pro rata basis and without consideration pursuant to the terms of its limited liability company agreement or limited partnership agreement, as applicable.  (Continued in footnote 2)</footnote>
        <footnote id="F2">Following on October 5, 2016, each of Colony American Homes Holdings I, L.P., a Delaware limited partnership, Colony American Homes Holdings II, L.P., a Cayman Islands exempted limited partnership, Colony American Homes Holdings III, L.P., a Delaware limited partnership, and Colony American Homes Holdings IV, L.P., a Cayman Islands exempted limited partnership transferred all of its Shares to all its limited partners on a pro rata basis and without consideration pursuant to the terms of its partnership agreement. (Continued in footnote 3)</footnote>
        <footnote id="F3">Following such transfers previously described: (i) Series X Holdco, LLC beneficially owned no Shares, (ii) Manager Holdco, LLC beneficially owned no Shares, (iii) Colony American Homes Holdings I, L.P. beneficially owned no Shares, (iv) Colony American Homes Holdings II, L.P. beneficially owned no Shares, (v) Colony American Homes Holdings III, L.P. beneficially owned no Shares, (vi) Colony American Homes Holdings IV, L.P. beneficially owned no Shares, (vii) Colony Distressed Credit Fund II, L.P. beneficially owned 2,951,315 Shares, (viii) ColCo Strategic Partners, L.P. beneficially owned 2,673,215 Shares, (ix) Colony Capital CAH, L.P. beneficially owned 53,464 Shares, (x) Colony AH Member, LLC beneficially owned 2,288,767 Shares, and (xi) CCCAH Management Partners, LLC beneficially owned 135,243 Shares.  The aggregate beneficial ownership of the entities described herein no longer exceeds 10%.</footnote>
        <footnote id="F4">Mr. Barrack is the direct or indirect control person of the general partner or the managing member, as the case may be, of each of Series X Holdco, LLC, Manager Holdco, LLC, Colony American Homes Holdings I, L.P., Colony American Homes Holdings II, L.P., Colony American Homes Holdings III, L.P., Colony American Homes Holdings IV, L.P., Colony Distressed Credit Fund II, L.P., ColCo Strategic Partners, L.P., Colony Capital CAH, L.P., Colony AH Member, LLC, and CCCAH Management Partners, LLC.</footnote>
        <footnote id="F5">The Reporting Person disclaims beneficial ownership of the Shares reported herein except to the extent of his pecuniary interest in such securities.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Thomas J. Barrack, Jr.</signatureName>
        <signatureDate>2016-10-07</signatureDate>
    </ownerSignature>
</ownershipDocument>
