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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2014-08-19</periodOfReport>

    <dateOfOriginalSubmission>2014-08-21</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001463101</issuerCik>
        <issuerName>Enphase Energy, Inc.</issuerName>
        <issuerTradingSymbol>ENPH</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001543816</rptOwnerCik>
            <rptOwnerName>Kortlang Benjamin John</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>2750 SAND HILL ROAD</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>MENLO PARK</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>94025</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2014-08-19</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>762640</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.0269</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>3810796</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnotes</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2014-08-19</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>523</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>10.0269</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>2614</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">The shares are directly held by KPCB Green Grown Fund, LLC (&quot;GGF Fund&quot;). All shares are held for convenience in the name of &quot;KPCB Holdings, Inc., as nominee&quot;.  The managing member for GGF Fund is KPCB GGF Associates, LLC (&quot;GGF Associates&quot;). The voting and dispositive control over the shares is shared by individual managing directors of GGF Associates, none of whom has veto power. Excludes 37,360 shares of Common Stock in the aggregate (the &quot;Sold Shares&quot;)  sold on August 19, 2014 by, and 186,683 shares of Common Stock in the aggregate (the &quot;Remaining Shares&quot;) beneficially owned by, individuals and entities associated with Kleiner Perkins Caufield &amp; Byers.  The Sold Shares include 523 shares of Common Stock sold by the reporting person and the Remaining Shares include 2,614 shares of Common Stock held by the reporting person.  (Continued on footnote 2).</footnote>
        <footnote id="F2">The Sold Shares were, and the Remaining Shares are, held for convenience in the name of &quot;KPCB Holdings, Inc. as nominee,&quot; for the accounts of such individuals and entities who each exercise their own voting and dispositive control over such shares.</footnote>
    </footnotes>

    <remarks>This Form 4 is amended and restated in its entirety to include 523 shares that were sold by the reporting person on August 19, 2014.

The reporting person disclaims beneficial ownership of these shares except to the extent of any pecuniary interest therein, and the filing of this report is not an admission that he is the beneficial owner of these shares for purposes of Section 16 or for any other purpose.</remarks>

    <ownerSignature>
        <signatureName>/s/ Susan Biglieri by power of attorney for Benjamin Kortlang</signatureName>
        <signatureDate>2014-09-18</signatureDate>
    </ownerSignature>
</ownershipDocument>
