McManus announced his retirement on 9 April 2021 after losing 6–3 to Bai Langning in the second qualifying round of the 2021 World Snooker Championship.

McManus was long considered a consistently good player, having a record of fourteen consecutive seasons in the Top 16, but never managed to achieve the success of his contemporaries Stephen Hendry, Ken Doherty, Ronnie O'Sullivan, John Higgins and Mark Williams.

[2] At the 1994 Masters, McManus defeated Nigel Bond 5–2 in the first round, Ken Doherty 5–1 in the quarter-finals, and then Neal Foulds 6–4 in the semi-final to set up his first triple crown tournament final against defending champion and fellow Scot Stephen Hendry.

[6] At the 2013 Welsh Open, McManus reached his first quarter-final since the 2006 Grand Prix, with a 4–2 win over the number 16 seed Barry Hawkins, followed by a dramatic comeback to beat Joe Perry 4–3, after having trailed 0–3.

He made a good start to the Players Tour Championship, reaching the quarter-finals of the first event, losing to Andrew Higginson by 4 frames to 3.

At the 2013 World Snooker Championship McManus, in qualifying, beat one of India's rising stars Aditya Mehta 10–9, in an epic encounter that lasted just over 9 hours.

In the final qualifying round he led Tom Ford 5–4 after the first session; he then reeled off five of the next six frames to book his place at the Crucible Theatre for the first time since 2006.

At the 2013 UK Championship, McManus defeated Joel Walker 6–5, winning the match on a respotted black, before losing to Michael Holt 4–6 in the last 64.

McManus continued his good form into the final European Tour event of the season, where he reached the last 16 by defeating players such as Neil Robertson and Graeme Dott before losing to Fergal O'Brien.

The 2014 World Snooker Championship, saw McManus beat John Higgins 10–7 in the first round and then defeat Ken Doherty 13–8, to set up another quarter-final with Mark Selby.

[11] McManus reached the quarter-finals of the Shanghai Masters by beating Jamie Jones to qualify, before defeating Ronnie O'Sullivan 5–3 and Stephen Maguire 5–1 but then lost to the eventual winner of the tournament Stuart Bingham 1–5.

[11] McManus won all three of his World Championship qualifying matches, defeating Michael Wasley, Andrew Pagett and Mitchell Mann to reach the main draw at the Crucible.

[15] McManus started strongly in the 2015–16 season, reaching the quarter-finals of the first event, the Riga Open, with wins over Stephen Maguire,[16] Judd Trump and others before losing to the eventual champion Barry Hawkins 2–4.

[23] In the 2016–17 season the furthest McManus could progress in an event was at the World Open, where he beat Jamie Cope and Liang Wenbo, but he was thrashed 0–5 by Thepchaiya Un-Nooh.

[24] He would also reach the third round in the 2016 Paul Hunter Classic, defeating Andy Hicks and Christopher Keogan, both 4–1, before coming up short against Tom Ford.

McManus started the 2017–18 season at number 32 in the world rankings; and would reach the third round of both the 2017 China Championship and 2017 Paul Hunter Classic.

He would also reach the second round of the 2017 UK Championship with a 6–3 win over Robin Hull; before losing a final frame decider to Jimmy Robertson 5–6.