Amateur years He was runner-up to
Stuart Carrington in the 2006
Junior Pot Black. He was runner-up in the 2008 European Under-19's Championship behind
Stephen Craigie. In the
2009/2010 season, he won the fifth event of the
International Open Series and finished fourth in the rankings. Thus, McGill received a place on the professional main tour for
2010/2011. He reached his first professional final, losing 1–6 to
John Higgins in the
2011 Scottish Professional Championship.
2011/2012 McGill did not manage to qualify for the main stage of any ranking event tournaments during the season, reaching the final qualifying on one occasion in an attempt to reach the
German Masters. He reached the semi-finals of
Event 3 in the minor-ranking
Players Tour Championship series, which included wins over experienced campaigners
Matthew Stevens and
Stephen Lee, before losing 0–4 to
Ben Woollaston. McGill's season concluded with an 8–10 defeat to
Anthony Hamilton in the penultimate qualifying round for the
World Championship, finishing the season ranked world number 50.
2012/2013 McGill could only qualify for the
China Open during the
2012/2013 season. He beat
David Grace,
Yu Delu and
Martin Gould to reach the venue in Beijing, where he defeated Heydari Nezhad Ehsan 5–3 in the wild-card round. He faced
Mark Allen in the last 32 and lost 1–5. McGill had a very good season in the
Players Tour Championship events by reaching his first ever minor-ranking final in the
European Tour Event 5, played in his homeland of Scotland. He saw off the likes of
Mark Davis and
Robert Milkins to make it through to the quarter-finals where he was 0–3 and 51 points down against
Thanawat Thirapongpaiboon to triumph 4–3. He was also 1–3 down in the semis to
Andrew Higginson, but recovered to win on a respotted black. McGill played
Ding Junhui in the final and came up short of winning the title as he lost 2–4. where he beat Milkins 4–2 before once again losing to Ding, this time by a 3–4 scoreline. McGill ended the season at number 48 in the rankings, at that point his highest position.
2013/2014 McGill lost in qualifying for the first three events of the season, but at the
Indian Open he reached the quarter-finals of a ranking tournament for the first time. He faced
Robbie Williams and was whitewashed 4–0. At the minor-ranking
Zhengzhou Open, he let a 2–0 lead slip in the semi-finals against
Liang Wenbo to lose 4–3. McGill was beaten in the last 32 of ranking events on three further occasions during the season. McGill eliminated both
Michael Georgiou and
Igor Figueiredo by 6–4 scorelines at the
UK Championship and then came back from 4–1 down against
Nigel Bond to triumph 6–5. He reached his first UK quarter-final by holding on to beat John Higgins 6–5 after being 4–1 up, but attributed the win to Higgins' bad form rather than his own good play. McGill then lost 6–4 to
Ronnie O'Sullivan after being 2–0 ahead and admitted he had blown his opportunity to knock out the four-time UK champion after failing to capitalise on the many chances that came his way during the game. However, he did break into the top 32 in the rankings for the first time after the event. McGill finished 21st on the European
Order of Merit to play in the
Grand Final and overcame
Peter Ebdon 4–1 in the first round, before losing 4–3 to
Joe Perry. McGill finished the year by qualifying for the televised stages of the
World Championship for the first time, after coming through three matches, ending with a 10–9 victory over
Mark King which he closed with a 127 break. McGill then knocked out defending champion
Mark Selby 13–9 in the second round, with Selby stating that he believed McGill could win the title if he could maintain his form. In the third ranking event quarter-final of his career, McGill lost 13–8 to
Shaun Murphy. The crowd warmed to McGill during his run in the tournament due to him smiling frequently between shots and displaying a relaxed attitude. He was the world number 24 afterwards, resulting in a climb of 21 places in 12 months.
2015/2016 The first ranking event McGill qualified for this season was the
International Championship and he thrashed
Sean O'Sullivan 6–0, before losing 6–1 to
Mark Selby. He exited in the second round of the
UK Championship 6–4 to
Luca Brecel and reached the last 32 stage of a ranking event for just the second time this season at the
Welsh Open with wins over
Liam Highfield and
Thepchaiya Un-Nooh, but lost 4–2 to
Neil Robertson. McGill overcame
Hatem Yassen 10–1,
Craig Steadman 10–9 and Thepchaiya Un-Nooh 10–7 to qualify for the
World Championship for the second year in a row. In a rematch of last year's quarter-final, McGill met Shaun Murphy and came back from 6–4 to win 10–8.> However, after he lost 13–9 to
Marco Fu in the second round, McGill described his play as rubbish.
2016/2017 McGill advanced to the quarter-finals of the
2016 Riga Masters, but was thrashed 5–0 by
Michael Holt. Another quarter-final followed at the
Indian Open by whitewashing
Stuart Bingham 4–0 and he followed that up by eliminating Stephen Maguire 4–1 and Shaun Murphy 4–2, after trailing 2–0. McGill played
Kyren Wilson in the final, the first to feature two players under 25 in five years, and they went into the interval at 2–2. After the break, McGill took three successive frames to seal his first ranking event title with a 5–2 victory. Three comfortable wins saw him advance to the quarter-finals of the
World Open, where he lost 5–2 to Thepchaiya Un-Nooh. McGill's fourth quarter-final of the season arrived at the
European Masters and he was ousted 4–2 by Neil Robertson. He was a seeded player in the
World Championship for the first time, but from 2–2 with Stephen Maguire in the first round he conceded 447 points without reply and McGill went on to be defeated 10–2. He just fell short of ending a season inside the top 16 for the first time as he was 17th.
2017/2018 McGill reached the final of the Indian Open again but was unable to defend his title, losing 5–1 to John Higgins. McGill was beaten in the first round of the
2018 Dafabet Masters, losing 6–4 to John Higgins. This marked his first appearance at the tournament. McGill lost to Mark Davis in the first round of the Snooker Shootout 2018. Davis scored a century break (102) to knock McGill, defending champion out of the tournament.
2018/2019 McGill's form slipped this season and saw his world ranking dropped from 14th to 23rd by the end of the season. He was unable to advance past the third round in all the tournaments.
2020/Present McGill beat
Jack Lisowski 10–9 in the first round of the
2020 World Championship. McGill then won two more matches to reach the semi-final where he played Kyren Wilson. With the match level at 16 frames apiece, McGill conceded 35 points in fouls in the deciding frame (which finished 83103) to lose the match 16–17. At the
2021 World Championship, McGill beat O'Sullivan 13–12 in the last 16 before losing 12–13 in the quarter-final to Bingham. McGill reached the last 16 of the
2022 World Championship where he was defeated 11–13 by Trump. After beating Trump 10–6 in the first round of the
2023 World Championship, McGill went on to reach the quarter-final where he was beaten 12–13 by
Si Jiahui. McGill failed to qualify for the
2024 World Championship after losing in qualifying to
He Guoqiang. It was the first time that he had failed to qualify for the
Crucible in ten years. McGill reached the final of the
2025 British Open where he was defeated 7–10 by Shaun Murphy. ==Performance and rankings timeline==