Morrison joined the Giants in 2003. Nicknamed "The Mo Train", Morrison began his career as a defensive minded forward, but has since become a bit of an enforcer, getting into scuffles and fights, much to the delight of Giants fans. Morrison also plays internationally for the Ireland national ice hockey team where he helped them win silver in the International Ice Hockey Federation World Championships Division III and gain promotion to Division II. At the end of the 2009/10 season Mark ended his career for the Giants.
Away from hockey, Morrison is married with two children and runs his own computer business.Mark's two brothers David and William also represented Team Ireland.