McCormack began his playing career in 1976 with Clydebank, making over 100 league appearances and scoring 24 times before joining St. Mirren in 1980. While playing for St. Mirren, McCormack acquired the nickname "Cowboy", because he had the same name as a professional boxer with that nickname. He moved to Dundee in 1984 before returning to the west of Scotland in 1986, spending single seasons with Airdrieonians and Partick Thistle before retiring in 1988.
McCormack returned to the game in September 2009, becoming first team coach at Second Division club Clyde. McCormack was promoted to manager, after John Brown was sacked, on 30 November 2009. McCormack was given a contract until the end of the 2009–2010 season, but he was sacked on 5 April, with the club facing almost certain relegation to the Third Division. Despite making a number of changes to the squad, McCormack had failed to arrest a decline in Clyde's fortunes and left the club in April 2010.