 McGinn started out at St Mirren FCBC (formerly the Football Club's Boys Club, now Youth Football Club), aged seven.He signed professional forms with St Mirren in July 2006, making his debut as a substitute on 1 January 2007 against Inverness CT. His first full appearance was in a 5–1 loss to Celtic on 20 January 2007, also scoring his first goal.For the 2007–08 season, McGinn started on bench before making his first start of the season against Celtic at Parkhead on 8 December, he scored the opening goal in a 1–1 draw.