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

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-06-09</periodOfReport>

    <notSubjectToSection16>1</notSubjectToSection16>

    <issuer>
        <issuerCik>0001019650</issuerCik>
        <issuerName>CENTRUE FINANCIAL CORP</issuerName>
        <issuerTradingSymbol>CFCB</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001008262</rptOwnerCik>
            <rptOwnerName>COOPER BRADLEY E</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>142 WEST 57TH STREET, 3RD FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10019</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>1</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001419136</rptOwnerCik>
            <rptOwnerName>Capital Z Partners III GP, L.P.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>142 WEST 57TH STREET, 3RD FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10019</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001419137</rptOwnerCik>
            <rptOwnerName>Capital Z Partners III GP, Ltd.</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>142 WEST 57TH STREET, 3RD FLOOR</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>NEW YORK</rptOwnerCity>
            <rptOwnerState>NY</rptOwnerState>
            <rptOwnerZipCode>10019</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>0</isOfficer>
            <isTenPercentOwner>1</isTenPercentOwner>
            <isOther>0</isOther>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2017-06-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>1533333</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F3"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>I</value>
                </directOrIndirectOwnership>
                <natureOfOwnership>
                    <value>See Footnotes</value>
                    <footnoteId id="F1"/>
                    <footnoteId id="F2"/>
                </natureOfOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable>
        <derivativeTransaction>
            <securityTitle>
                <value>Restricted Stock Units</value>
            </securityTitle>
            <conversionOrExercisePrice>
                <value>0.0</value>
            </conversionOrExercisePrice>
            <transactionDate>
                <value>2017-06-09</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>D</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>598.0861</value>
                </transactionShares>
                <transactionPricePerShare>
                    <footnoteId id="F4"/>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <exerciseDate>
                <footnoteId id="F4"/>
            </exerciseDate>
            <expirationDate>
                <value>2017-06-09</value>
            </expirationDate>
            <underlyingSecurity>
                <underlyingSecurityTitle>
                    <value>Common Stock</value>
                </underlyingSecurityTitle>
                <underlyingSecurityShares>
                    <value>598.0861</value>
                </underlyingSecurityShares>
            </underlyingSecurity>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>0</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </derivativeTransaction>
    </derivativeTable>

    <footnotes>
        <footnote id="F1">Directly owned by Capital Z Partners Centrue AIV, L.P. (&quot;Capital Z Centrue&quot;). Capital Z Partners III GP, L.P. (&quot;Capital Z III GP LP&quot;) is the general partner of Capital Z Centrue. Capital Z Partners III GP, Ltd. (&quot;Capital Z III GP LTD&quot;) is the general partner of Capital Z III GP LP and the ultimate general partner of Capital Z Centrue. Each of Capital Z III GP LP, Capital Z III GP LTD and Capital Z Centrue disclaims beneficial ownership of securities held by any other entity except to the extent of any indirect pecuniary interest (within the meaning of Rule 16a-1 of the Exchange Act) in an indeterminate portion of the securities beneficially owned by such other entity.</footnote>
        <footnote id="F2">Bradley E. Cooper, a director of the Issuer, is a limited partner of Capital Z III GP LP and is an officer and director of Capital Z III GP LTD. Mr. Cooper disclaims beneficial ownership of such securities except to any indirect pecuniary interest in an indeterminate portion of the securities beneficial owned by such other entities.</footnote>
        <footnote id="F3">Disposed of pursuant to the Agreement and Plan of Merger, dated January 26, 2017, by and among Midland States Bancorp, Inc., Sentinel Acquisition, LLC, and the Company, and will be converted to the right to receive the per share value as set forth in the merger agreement.</footnote>
        <footnote id="F4">Each Restricted Stock Unit was vested in connection with the Agreement and Plan of Merger, dated January 26, 2017, by and among Midland States Bancorp, Inc., Sentinel Acquisition, LLC, and the Company, and will be converted to the right to receive the Per Share Value as set forth in the merger agreement.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/ Bradley E. Cooper</signatureName>
        <signatureDate>2017-06-09</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Craig Fisher, General Counsel - Authorized Signatory for Capital Z Partners III GP, L.P.</signatureName>
        <signatureDate>2017-06-09</signatureDate>
    </ownerSignature>

    <ownerSignature>
        <signatureName>/s/ Craig Fisher, General Counsel - Authorized Signatory for Capital Z Partners III GP, Ltd..</signatureName>
        <signatureDate>2017-06-09</signatureDate>
    </ownerSignature>
</ownershipDocument>
