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

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-06-17</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000730708</issuerCik>
        <issuerName>SEACOAST BANKING CORP OF FLORIDA</issuerName>
        <issuerTradingSymbol>SBCF</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001228649</rptOwnerCik>
            <rptOwnerName>GOLDSTEIN ROBERT</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>C/O CAPGEN CAPITAL GROUP III LP</rptOwnerStreet1>
            <rptOwnerStreet2>280 PARK AVENUE 40TH FLOOR WEST SUITE 40</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10017</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001488108</rptOwnerCik>
            <rptOwnerName>CapGen Capital Group III LLC</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>280 PARK AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>40TH FLOOR WEST SUITE 401</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10017</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001488107</rptOwnerCik>
            <rptOwnerName>CapGen Capital Group III LP</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>280 PARK AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>40TH FLOOR WEST SUITE 401</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10017</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle></officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001453863</rptOwnerCik>
            <rptOwnerName>Ludwig Eugene</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>280 PARK AVENUE</rptOwnerStreet1>
            <rptOwnerStreet2>40TH FLOOR WEST SUITE 401</rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10017</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, par value $0.10 per share</value>
            </securityTitle>
            <transactionDate>
                <value>2010-06-29</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>C</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>9715862</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F1"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>15715862</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Held by CapGen Capital Group III LP</value>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Series B Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1.45</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2010-06-17</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
                <footnoteId id="F1"/>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>14088</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>1000</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F5"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock, par value $0.10 per share</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>9715862</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>14088</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Held by CapGen Capital Group III LP</value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
        <derivativeTransaction>
            <securityTitle>
                <value>Series B Preferred Stock</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>1.45</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2010-06-29</value>
            </transactionDate>
            <deemedExecutionDate></deemedExecutionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>C</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>14088</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F5"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F5"/>
            </exerciseDate>
            <expirationDate>
                <footnoteId id="F5"/>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock, par value $0.10 per share</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>9715862</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                    <footnoteId id="F2"/>
                    <footnoteId id="F3"/>
                    <footnoteId id="F4"/>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>Held by CapGen Capital Group III LP</value>
                </natureOfOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">On April 9, 2010, CapGen Capital Group III LP (&quot;CapGen LP&quot;) executed a letter agreement (the &quot;Letter Agreement&quot;) pursuant to which, on June 17, 2010, CapGen LP acquired 14,088 shares of Mandatorily Convertible Noncumulative Nonvoting Preferred Stock, Series B, $0.10 par value per share (the &quot;Series B Preferred Stock&quot;), of Seacoast Banking Corporation of Florida (the &quot;Issuer&quot;), which shares of Series B Preferred Stock were mandatorily converted into 9,715,862 shares of common stock, par value $0.10 per share (&quot;Common Stock&quot;) of the Issuer on June 29, 2010,  based on a conversion price of $1.45 per share pursuant to the terms of the Issuer's Amended and Restated Articles of Incorporation filed with the Florida Secretary of State on April 9, 2010.</footnote>
        <footnote id="F2">CapGen Capital Group III LLC (&quot;CapGen LLC&quot;) is the sole general partner of CapGen LP, and Mr. Eugene A. Ludwig is the managing member of CapGen LLC.  Mr. Robert Goldstein serves as a director of the Issuer.   CapGen LP is the direct holder of the shares of Common Stock and Series B Preferred Stock referenced on this Form 4.</footnote>
        <footnote id="F3">As the sole general partner of CapGen LP, CapGen LLC may be deemed to be the indirect beneficial owner of such shares of Common Stock under Rule 16a-1(a)(2) promulgated under the Securities Exchange Act of 1934, as amended (the &quot;Exchange Act&quot;). Pursuant to Rule 16a-1(a)(4) promulgated under the Exchange Act, CapGen LLC disclaims that it is the beneficial owner of such shares, except to the extent of its pecuniary interest.</footnote>
        <footnote id="F4">As the managing member of CapGen LLC, Mr. Ludwig may be deemed to be the indirect beneficial owner of such shares under Rule 16a-1(a)(2) promulgated under the Exchange Act. As a principal member and member of the investment committee of CapGen LLC, the general partner of CapGen LP, Mr. Goldstein may be deemed to be the indirect beneficial owner of such shares under Rule 16a-1(a)(2) promulgated under the Exchange Act. Pursuant to Rule 16a-1(a)(4) promulgated under the Exchange Act, each of Mr. Ludwig and Mr. Goldstein disclaims that he is the beneficial owner of such shares, except to the extent of his pecuniary interest.</footnote>
        <footnote id="F5">All shares of Series B Preferred Stock automatically converted into shares of Common Stock on June 29, 2010, which was the fifth business day following the receipt by the Issuer on June 22, 2010 of the approval by the holders of the Common Stock of the issuance of the Common Stock upon the mandatory conversion for purposes of NASDAQ Stock Market Rule 5635. The Series B Preferred Stock automatically converted into a number of shares of Common Stock calculated by dividing (i) the $1,000 per share liquidation amount by (ii) the applicable conversion price, which was $1.45 per share.</footnote>
    </footnotes>

    <remarks>CapGen LP, CapGen LLC and Mr. Ludwig disclaim their status as directors by deputization by virtue of Mr. Goldstein's position as a member of the board of directors of the Issuer.</remarks>

    <ownerSignature>
        <signatureName>/s/ Robert B. Goldstein</signatureName>
        <signatureDate>2010-07-26</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Eugene A. Ludwig, the managing member of CapGen Capital Group III LLC, the general partner of CapGen Capital Group III LP</signatureName>
        <signatureDate>2010-07-26</signatureDate>
    </ownerSignature>
</ownershipDocument>
