<SEC-DOCUMENT>0001628280-17-004560.txt : 20170501
<SEC-HEADER>0001628280-17-004560.hdr.sgml : 20170501
<ACCEPTANCE-DATETIME>20170501173818
ACCESSION NUMBER:		0001628280-17-004560
CONFORMED SUBMISSION TYPE:	4
PUBLIC DOCUMENT COUNT:		1
CONFORMED PERIOD OF REPORT:	20170427
FILED AS OF DATE:		20170501
DATE AS OF CHANGE:		20170501

ISSUER:		

	COMPANY DATA:	
		COMPANY CONFORMED NAME:			MITEK SYSTEMS INC
		CENTRAL INDEX KEY:			0000807863
		STANDARD INDUSTRIAL CLASSIFICATION:	COMPUTER PERIPHERAL EQUIPMENT, NEC [3577]
		IRS NUMBER:				870418827
		STATE OF INCORPORATION:			DE
		FISCAL YEAR END:			0930

	BUSINESS ADDRESS:	
		STREET 1:		8911 BALBOA AVE.
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92123
		BUSINESS PHONE:		858-309-1700

	MAIL ADDRESS:	
		STREET 1:		8911 BALBOA AVE.
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92123

REPORTING-OWNER:	

	OWNER DATA:	
		COMPANY CONFORMED NAME:			Gray Jason
		CENTRAL INDEX KEY:			0001577363

	FILING VALUES:
		FORM TYPE:		4
		SEC ACT:		1934 Act
		SEC FILE NUMBER:	001-35231
		FILM NUMBER:		17802182

	MAIL ADDRESS:	
		STREET 1:		600 B. STREET SUITE 100
		CITY:			SAN DIEGO
		STATE:			CA
		ZIP:			92101
</SEC-HEADER>
<DOCUMENT>
<TYPE>4
<SEQUENCE>1
<FILENAME>wf-form4_149367468369450.xml
<DESCRIPTION>FORM 4
<TEXT>
<XML>
<?xml version="1.0"?>
<ownershipDocument>

    <schemaVersion>X0306</schemaVersion>

    <documentType>4</documentType>

    <periodOfReport>2017-04-27</periodOfReport>

    <notSubjectToSection16>0</notSubjectToSection16>

    <issuer>
        <issuerCik>0000807863</issuerCik>
        <issuerName>MITEK SYSTEMS INC</issuerName>
        <issuerTradingSymbol>MITK</issuerTradingSymbol>
    </issuer>

    <reportingOwner>
        <reportingOwnerId>
            <rptOwnerCik>0001577363</rptOwnerCik>
            <rptOwnerName>Gray Jason</rptOwnerName>
        </reportingOwnerId>
        <reportingOwnerAddress>
            <rptOwnerStreet1>600 B STREET, SUITE 100</rptOwnerStreet1>
            <rptOwnerStreet2></rptOwnerStreet2>
            <rptOwnerCity>SAN DIEGO</rptOwnerCity>
            <rptOwnerState>CA</rptOwnerState>
            <rptOwnerZipCode>92101</rptOwnerZipCode>
            <rptOwnerStateDescription></rptOwnerStateDescription>
        </reportingOwnerAddress>
        <reportingOwnerRelationship>
            <isDirector>0</isDirector>
            <isOfficer>1</isOfficer>
            <isTenPercentOwner>0</isTenPercentOwner>
            <isOther>0</isOther>
            <officerTitle>GC, Secretary &amp; Admin Officer</officerTitle>
            <otherText></otherText>
        </reportingOwnerRelationship>
    </reportingOwner>

    <nonDerivativeTable>
        <nonDerivativeTransaction>
            <securityTitle>
                <value>Common Stock</value>
            </securityTitle>
            <transactionDate>
                <value>2017-04-27</value>
            </transactionDate>
            <transactionCoding>
                <transactionFormType>4</transactionFormType>
                <transactionCode>S</transactionCode>
                <equitySwapInvolved>0</equitySwapInvolved>
            </transactionCoding>
            <transactionAmounts>
                <transactionShares>
                    <value>7789</value>
                    <footnoteId id="F1"/>
                </transactionShares>
                <transactionPricePerShare>
                    <value>8.20</value>
                </transactionPricePerShare>
                <transactionAcquiredDisposedCode>
                    <value>D</value>
                </transactionAcquiredDisposedCode>
            </transactionAmounts>
            <postTransactionAmounts>
                <sharesOwnedFollowingTransaction>
                    <value>87211</value>
                </sharesOwnedFollowingTransaction>
            </postTransactionAmounts>
            <ownershipNature>
                <directOrIndirectOwnership>
                    <value>D</value>
                </directOrIndirectOwnership>
            </ownershipNature>
        </nonDerivativeTransaction>
    </nonDerivativeTable>

    <derivativeTable></derivativeTable>

    <footnotes>
        <footnote id="F1">Represents the disposition of shares that were automatically sold by Mitek Systems, Inc. to pay withholding taxes upon the vesting of 20,000 restricted stock units.</footnote>
    </footnotes>

    <remarks></remarks>

    <ownerSignature>
        <signatureName>/s/ Jason Gray</signatureName>
        <signatureDate>2017-05-01</signatureDate>
    </ownerSignature>
</ownershipDocument>
</XML>
</TEXT>
</DOCUMENT>
</SEC-DOCUMENT>
