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Proc-Type: 2001,MIC-CLEAR
Originator-Name: webmaster@www.sec.gov
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MIC-Info: RSA-MD5,RSA,
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<SEC-DOCUMENT>0000939057-10-000382.txt : 20101210
<SEC-HEADER>0000939057-10-000382.hdr.sgml : 20101210
<ACCEPTANCE-DATETIME>20101210115913
ACCESSION NUMBER:		0000939057-10-000382
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20101208
FILED AS OF DATE:		20101210
DATE AS OF CHANGE:		20101210

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Gaspard Matthew Scott
		CENTRAL INDEX KEY:			0001452769

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-33652
		FILM NUMBER:		101244116

	MAIL ADDRESS:	
		STREET 1:		201 WELLS AVENUE SOUTH
		CITY:			RENTON
		STATE:			WA
		ZIP:			98057

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			First Financial Northwest, Inc.
		CENTRAL INDEX KEY:			0001401564
		STANDARD INDUSTRIAL CLASSIFICATION:	SAVINGS INSTITUTIONS, NOT FEDERALLY CHARTERED [6036]
		IRS NUMBER:				000000000
		STATE OF INCORPORATION:			WA
		FISCAL YEAR END:			1231

	BUSINESS ADDRESS:	
		STREET 1:		201 WELLS AVENUE SOUTH
		CITY:			RENTON
		STATE:			WA
		ZIP:			98057
		BUSINESS PHONE:		(425) 255-4400

	MAIL ADDRESS:	
		STREET 1:		201 WELLS AVENUE SOUTH
		CITY:			RENTON
		STATE:			WA
		ZIP:			98057
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>primary_doc.xml
<DESCRIPTION>PRIMARY DOCUMENT
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0303</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2010-12-08</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0001401564</issuerCik>
        <issuerName>First Financial Northwest, Inc.</issuerName>
        <issuerTradingSymbol>FFNW</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001452769</rptOwnerCik>
            <rptOwnerName>Gaspard Matthew Scott</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>201 WELLS AVENUE SOUTH</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>RENTON</rptOwnerCity>
            <rptOwnerState>WA</rptOwnerState>
            <rptOwnerZipCode>98057</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>Senior VP External Affairs</officerTitle>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock, $0.01 par value</value>
            </securityTitle>
            <transactionDate>
                <value>2010-12-08</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>P</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionTimeliness>
                <value></value>
            </transactionTimeliness>
            <transactionAmounts>
                <transactionShares>
                    <value>10000</value>
                </transactionShares>
                <transactionPricePerShare>
                    <value>3.52</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>A</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>42000</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                    <footnoteId id="F1"/>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <footnotes>
        <footnote id="F1">Represents purchase of 10,000 through IRA; includes award of 32,000 shares of restricted stock under the 2008 Equity Incentive Plan, which vests in equal installments of 20% per year beginning on January 1, 2010.</footnote>
    </footnotes>

    <ownerSignature>
        <signatureName>/s/Matthew Scott Gaspard</signatureName>
        <signatureDate>2010-12-10</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
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