|Date of birth||31 August 1990|
|Place of birth||Thurso, Scotland|
|Height||1.75 m (5 ft 9 in)|
* Senior club appearances and goals counted for the domestic league only and correct as of 10 May 2015.
Having not made the first team at English clubs Liverpool and Fulham, he began his professional career with Airdrie United in January 2011, spending half a season there before moving to top-flight team Dundee United. He remained with Dundee United until February 2015, when he was signed by Celtic for £250,000.
Mackay-Steven made his debut for the Scotland national football team in 2013.
Born in Thurso, Highland, Mackay-Steven began his career with Ross County before moving to English Premier League side Liverpool in 2007. After spending two years at Anfield in the reserve and youth sides, Mackay-Steven was released after an injury-plagued season. He trained with Fulham before eventually returning to Scotland.
On 11 January 2011, Mackay-Steven joined Scottish Second Division side Airdrie United. He made his debut a week later in the fourth round of the Scottish Cup, starting against Greenock Morton at Cappielow Park and scoring the opening goal of a 2–2 draw from 25 yards out. A week later, in the replay at the Excelsior Stadium, Mackay-Steven scored again, albeit in a 2–5 defeat. He played 19 league matches in the remainder of the season, but did not score.
|“||There is great potential there. Gary is a welcome addition to our squad.||”|
—Peter Houston, BBC Sport, 13 July 2011
On 13 July 2011, Mackay-Steven signed a two-year deal with Scottish Premier League club Dundee United. He made his début eight days later as an 80th-minute substitute for Johnny Russell in a UEFA Europa League match against Śląsk Wrocław, which his club won 3–2 but were nonetheless eliminated on the away goals rule. On 24 July, he made his league debut for the club on the opening day of the season, coming on for Barry Douglas for the last 30 minutes of a 1–1 draw against Kilmarnock at Tannadice Park. On 29 August, Mackay-Steven scored his first goal for the club (and his first career league goal), netting in the 3–3 draw at St Johnstone. By the end of the 2011–12 season, Mackay-Steven had established a regular starting place in the first team and become a huge fans' favourite thanks to his large role in helping turn around United's poor start to the season. Mackay-Steven signed an extended contract with the club in January 2012.
Blackburn Rovers scouts were reported to have been watching Mackay-Steven on 24 August 2013, in Dundee United's 4–0 victory over St. Johnstone, a game in which he scored. On 12 April 2014, he scored Dundee United's second goal in a 3–1 win against Rangers in the Scottish Cup semi–final at Ibrox. In the final on 17 May, he started in the 0–2 defeat to St. Johnstone at Celtic Park, being substituted for Ryan Gauld after 64 minutes.
On 16 January 2015, Mackay-Steven signed a pre-contract agreement to join Celtic at the end of the season on the expiry of his Dundee United contract. In the January transfer window, he had been pursued by Nigel Clough, manager of English League One club Sheffield United, who made three bids up to £100,000 while Dundee United wanted a minimum of £250,000. On the transfer deadline day, 2 February, Celtic made an offer of £250,000 and the move was completed immediately, with his Dundee United teammate Stuart Armstrong joining in a separate deal at the same time. Five days later, the pair watched from the stands as Celtic won 2–0 at Dundee F.C. in the fifth round of the Scottish Cup.
Mackay-Steven made his debut on 11 February away to Partick Thistle, scoring after 37 seconds in a 3–0 victory. His first goal at Celtic Park came on 1 March as the third in a 4–0 win over Aberdeen, with a shot from 20 yards. On 15 March Celtic won the Scottish League Cup Final against Dundee United, but Mackay-Steven was cup-tied, having already represented Dundee United in the tournament that season.
Mackay-Steven made his senior international debut for Scotland on 15 November 2013, replacing Craig Conway for the last six minutes of a goalless friendly draw against the United States at Hampden Park.
- As of 10 May 2015
- "Mackay-Steven fair thrilled to joined SPL side Dundee United". BBC Sport. 15 July 2011. Retrieved 18 July 2011.
- "Official Twitter feed". 15 June 2011. Retrieved 19 July 2011.
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- "Airdrie bring in former Liverpool youth". Scottish Football League. 11 July 2011. Retrieved 18 July 2011.
- "Morton 2-2 Airdrie". BBC Sport. 18 January 2011. Retrieved 16 January 2015.
- "Airdrie 2-5 Morton". BBC Sport. 25 January 2011. Retrieved 16 January 2015.
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- "Dundee United 1-1 Kilmarnock". Scottish Professional Football League. Retrieved 2 March 2015.
- "St Johnstone 3 Dundee United 3: Perth men count cost of late madness". The Courier. 29 August 2011. Retrieved 30 August 2011.
- "Dundee United's Gary Mackay-Steven extends contract until 2015". BBC Sport (BBC). 13 January 2012. Retrieved 13 January 2012.
- "Dundee United star Gary Mackay-Steven aims to show Scotland boss Gordon Strachan what he's missing". Daily Record. 26 August 2013. Retrieved 3 September 2013.
- Wilson, Richard (12 April 2014). "Rangers 1-3 Dundee United". BBC Sport. Retrieved 14 April 2014.
- Wilson, Richard (17 May 2014). "St Johnstone 2-0 Dundee Utd". BBC Sport. Retrieved 8 September 2014.
- Campbell, Andy (1 January 2015). "Dundee Utd 6-2 Dundee". BBC Sport. Retrieved 7 January 2015.
- "Celtic: Gary Mackay-Steven agrees summer switch". BBC Sport. 16 January 2015. Retrieved 16 January 2015.
- Spence, Jim (2 February 2015). "Stuart Armstrong & Gary Mackay-Steven join Celtic". BBC Sport. Retrieved 3 February 2015.
- McVake, Roddie (7 February 2015). "Dundee 0-2 Celtic". BBC Sport. Retrieved 8 February 2015.
- "Partick Thistle 0-3 Celtic". BBC Sport. 11 February 2015. Retrieved 11 February 2015.
- Wilson, Richard (1 March 2015). "Celtic 4-0 Aberdeen". BBC Sport. Retrieved 2 March 2015.
- Wilson, Richard (14 March 2015). "Dundee Utd 0-2 Celtic". BBC Sport. Retrieved 15 March 2015.
- Lamont, Alasdair (15 November 2013). "Scotland 0-0 USA". BBC Sport. Retrieved 7 January 2015.
- "Gary Mackay-Steven career stats". Soccerbase. Retrieved 26 January 2015.