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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4/A</documentType>

    <periodOfReport>2013-11-04</periodOfReport>

    <dateOfOriginalSubmission>2013-11-04</dateOfOriginalSubmission>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001376339</issuerCik>
        <issuerName>MIMEDX GROUP, INC.</issuerName>
        <issuerTradingSymbol>MDXG</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0000901434</rptOwnerCik>
            <rptOwnerName>PETIT PARKER H</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O MIMEDX GROUP, INC.</rptOwnerStreet1>
            <rptOwnerStreet2>1775 WEST OAK COMMONS CT., N.E.</rptOwnerStreet2>
            <rptOwnerCity>MARIETTA</rptOwnerCity>
            <rptOwnerState>GA</rptOwnerState>
            <rptOwnerZipCode>30062</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Chief Executive Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2013-11-04</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>250000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1.00</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>8935020</value>
                    <footnoteId id="F1"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Warrant</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1.00</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2013-11-04</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>M</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>250000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>0</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <value>2010-11-04</value>
            </exerciseDate>
            <expirationDate>
                <value>2013-11-04</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>250000</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>975000</value>
                    <footnoteId id="F2"/>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Note:  This amended Form 4 is being filed to amend the Transaction Code applicable to the reported transaction and the beneficial ownership total in Column 9 of Table I.  Includes 5,710,020 shares held directly by Mr. Petit; 150,000 shares held by The Parker H. Petit Grantor Trust, of which he serves as Trustee; 150,000 shares held by Petit Investments, L.P., of which he serves as General partner and limited partner and possesses shared voting and investment control; 975,000 shares held by Cox Road Partners II, LLLP, 975,000 shares help by Cox Road Partners, LLLP and 975,000 shares held by Petit Investments II, L.L.L.P., Limited Liability Partnerships over which Mr. Petit possesses sole voting and investment control.  Mr. Petit also has 106,000 shares of unvested restricted stock.  He has no voting rights with respect to the unvested restricted stock.</footnote>
        <footnote id="F2">325,000 warrants held by Cox Road Partners II LLP, 325,000 warrants held by Cox Road Partners LLLP and 325,000 warrants held by Petit Investments II, L.L.L.P., Limited Liability Partnerships over which Mr. Petit possesses sole voting and investment control.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Michael J. Senken, by Power of Attorney</signatureName>
        <signatureDate>2013-11-04</signatureDate>
    </ownerSignature>
</ownershipDocument>
