The 31-year-old has left the Blues to take up a new career opportunity within his job in the rail industry.
Stewart joined Stranraer in the summer, returning to the club where he enjoyed a successful spell on loan from Falkirk in 2007.
Stewart began his senior career at Falkirk, having been on the books at Celtic and Partick Thistle as a youth, and also played for Bradford City, Hamilton (on loan), Dundee, Kilmarnock, Derry City, Raith Rovers, Dumbarton and Stirling Albion.
A Stranraer club statement said all at Stair Park wished Mark the very best for the future.