McGinn began his career with St Mirren in his native Scotland, before moving south of the border to sign for English Championship side Watford where he spent three and a half years but was on the sidelines for over a year due to a knee injury and was loaned to Shrewsbury Town upon his return to fitness.

[citation needed] The following season McGinn established himself as a first-team regular for Watford, missing just four games between August and the end of February, before damaging his knee ligaments in a 1–1 draw against Doncaster Rovers.

McGinn returned to fitness a year later, playing 45 minutes in a reserve game, insisting afterwards that he felt good and stronger than when he got injured.

[5] In July 2012, McGinn signed a new contract to keep him at Vicarage Road for another year, with a one-year option held by the Hornets to extend the deal.

[6] Having failed to make an appearance for Watford during the first half of the following season, in January McGinn signed for Shrewsbury Town on loan until the end of April.

[9] Following his release from Watford, McGinn signed for League One side Sheffield United in June 2013, agreeing a two-year contract with the option of a third year.

[10] McGinn made his debut for the Blades in the opening fixture of the following season, in a 2–1 home win against Notts County.

[11] Having been allowed to join Dundee on loan on 30 January 2015, McGinn's contract was then cancelled by Sheffield United on 2 February 2015.

[17] McGinn signed an 18-month contract with St Mirren in January 2017,[18] and played a major part in helping the club avoid relegation.

[27][28] In March 2024, McGinn won the League One title with the Bairns on the same night they destroyed Montrose at Links Park.

[32] McGinn played for Scotland under-19s in a goalless draw against Slovakia in 2007,[33] and marked his debut for the under-21s by scoring in a 5–2 win against Albania in April 2009.

Between May 2018 and January 2020, Stephen and Paul both represented St Mirren, and the brothers were in the same squad at Hibernian for the 2020–21 season.