Ranked 41st in the world, he defeated Peter Ebdon and Joe Perry (both 5–4), John Higgins 5–3 and Stephen Lee 6–4 to meet Jimmy White in the final.

He lost 6–10 in the opening round to Ronnie O'Sullivan, who admitted to being impressed by Maguire's performance and tipped him to be a future world champion.

[44][45] He defeated Stephen Hendry and John Higgins at the UK Championship to set up a quarter-final with world number seven Judd Trump, but lost the match 3–6.

[53] At the 2012 World Championship, Maguire defeated Luca Brecel 10–5 in the first round, Joe Perry 13–7 in the second, and Stephen Hendry 13–2 in the quarter-finals with a session to spare.

[55] Maguire lost his semi-final 12–17 to Ali Carter,[56] and finished the season ranked world number four, meaning he had climbed four places during the year.

[57] Maguire lost in the first round of the opening ranking event of the new season with a 4–5 defeat to Rod Lawler at the Wuxi Classic and then could not advance out of his group in the Six-red World Championship.

[61][62] He defeated Anthony Hamilton, Matthew Stevens, Alan McManus and Judd Trump to face Stuart Bingham in the final.

[66] He reached the semi-finals of the inaugural Indian Open and fought back from 0–3 down against home favourite Aditya Mehta to level at 3–3 but lost the deciding frame.

[67] At the UK Championship, Maguire came back from 2–5 down against Luca Brecel in the second round to win 6–5 and also edged past Liang Wenbo 6–5, before beating John Higgins 6–3.

[66][68] He lost 2–6 to Neil Robertson in the quarter-finals, with the Australian criticising the playing condition of the snooker table as "absolute garbage" after the match.

[66] Maguire produced a comeback from 3–6 and 6–9 down against Ryan Day to send the first-round match into a deciding frame but, despite having a chance to win, he lost 9–10.

[75] In June 2014, Maguire whitewashed Judd Trump 5–0 to reach the quarter-finals of the Wuxi Classic where he lost 4–5 against Martin Gould, despite making the tournament's highest break of 145.

[79] He then beat Mark Williams 6–2, David Morris 6–3 and Marco Fu 6–4 to play in his first major ranking event semi-final in over a year.

[81] A week later, Maguire continued his resurgence of form to win the inaugural Lisbon Open, defeating Matthew Selt 4–2 in the final.

[89] Maguire and teammate John Higgins lost in the final of the 2015 Snooker World Cup to Chinese teenagers Zhou Yuelong and Yan Bingtao.

[90] Maguire then reached the semi-finals of the first ranking event of the year by thrashing Judd Trump 5–1 at the Australian Goldfields Open, but he lost 1–6 to Martin Gould.

[93] He was knocked out in the quarter-finals of the German Masters 1–5 by Graeme Dott and the first round of both the Welsh Open (3–4 to Martin O'Donnell) and the World Grand Prix (0–4 to Higgins).

[95] This meant that Maguire needed a strong run at the China Open to avoid having to qualify for the 2016 World Championship at the end of the season.

[96][97] Despite his automatic qualification for the World Championship, Maguire stated that he felt embarrassed at being unable to motivate himself for the event, after losing 7–10 to Alan McManus in the first round.

[101] He lost 3–6 to Luca Brecel in the fourth round of the UK Championship and was then defeated 1–5 against Mark Selby in the quarter-finals of the China Open.

[107] In December, with wins over Yuan Sijun, Jak Jones, Liang Wenbo, Graeme Dott, and Joe Perry, Maguire advanced to the semi-finals of the UK Championship again, but was defeated 4–6 by the eventual champion Ronnie O'Sullivan.

[109] In February, Maguire progressed to the semi-finals of another ranking event, this time at the World Grand Prix, but lost 4–6 to O'Sullivan despite leading 4–2.

[110] He qualified for the 2018 World Championship after beating Allan Taylor, Hammad Miah, and Hossein Vafaei, and faced Ronnie O'Sullivan in the first round.

[111] Maguire made a strong start to the 2018–19 season; with wins against Joe Perry and Kyren Wilson, he reached the semi-finals of the Riga Masters but lost 1–5 to Jack Lisowski.

[116] At the 2019 World Championship, Maguire won both of his first two rounds against Tian Pengfei and James Cahill, the latter ending in a final-frame decider, but was unable to replicate the same feat against Judd Trump in the quarter-finals, losing 6–13.

[117] In September 2019, Maguire won the Six-red World Championship for the second time, after beating his fellow countryman John Higgins 8–6 in the final.

[119] The highlight of the extended 2019–20 season for Maguire was the Tour Championship in June, where he beat Mark Allen 10–6 in the final, to secure the £150,000 winner's prize and his first ranking event title since 2013.

As the match was about to begin, Maguire realised he had forgotten to bring his chalk with him so he asked referee Johan Oomen for permission to leave the arena.

[125] Unlike fellow professionals, he is permitted to play with his collar open and not wear a bow tie in competition because of a neck condition.