[6] In September, it was announced that his match at the Players Tour Championship – Event 3 against Steve Davis was under investigation due to unusual betting patterns.

[11][12] Un-Nooh lost in the qualifying rounds for the first four ranking events of the 2013–14 season, but then beat Gerard Greene 6–5 to reach the International Championship in Chengdu, China.

He beat Ronnie O'Sullivan 5–4 in qualifying for the German Masters, with the reigning world champion playing high risk exhibition shots throughout the match, but Un-Nooh was whitewashed 5–0 by Jack Lisowski in the first round.

[17] He then reached the last 16 of a ranking event for the first time by beating Andrew Higginson 5–1 and lost 5–2 to Graeme Dott, despite missing the final pink when on a 147 break during the match.

[13] Un-Nooh advanced to the last 32 of the China Open by whitewashing 1997 world champion Ken Doherty 5–0, before losing 5–3 against Ding Junhui.

[20] Un-Nooh won five games to reach the semi-finals of the Xuzhou Open where he beat Mark Williams 4–1 to play in his first final in a professional event.

[22] Nevertheless, he whitewashed Luca Brecel 4–0 and then recorded wins over Jamie Jones and Mark Davis to reach the semi-finals of a ranking event for the first time.

It earned him £40,000, and he won the match 4–1 before then narrowly beating Mark Allen and David Grace both 4–3, to reach the semi-finals of a ranking tournament for the second successive event.

He struggled to build on this afterward, for he could not win a first-round match until the 2017 Welsh Open, in which he beat Ben Woollaston 4–0 and then saw off Ryan Day 4–1, before being defeated 4–1 by Barry Hawkins.

[36] After a last 16 finish at the Gibraltar Open his season ended on a low note as he lost in the first round of qualifying for the World Championship with a 10–9 defeat against Peter Lines.

[38] However he did qualify for the World Championship for the second year running after recording victories over Alexander Ursenbacher (10–8), Adam Stefanow (10–4), and Alfie Burden (10–8).

[41] Un-Nooh's best showing in a ranking event for the first half of the 2018–19 snooker season was at the Northern Ireland Open, where he defeated Robert Milkins 4–0, Ross Muir 4–0, Chris Totten 4–1, and Robbie Williams 4–0 before meeting Mark Selby in the quarter-finals where he lost 5–3.

[45] In the first half of the 2019–20 snooker season, Un-Nooh's best performances in ranking events were last 16 finishes at the Riga Masters and English Open, where he was defeated by Kurt Maflin and Ricky Walden respectively.

[47] Just one week later at the World Open, Un-Nooh recorded victories over Zhang Yang, Craig Steadman, Sunny Akani, David Gilbert and Kyren Wilson to reach his second ranking final.

[46] For the 2020 World Snooker Championship delayed by the COVID-19 pandemic, he came through qualifying for the third year in a row with victories over Dominic Dale and Liam Highfield, and was drawn against Ronnie O'Sullivan in the first round.

He defeated Andrew Pagett (6–4), Jak Jones (6–5), and recorded a first ever victory over Matthew Selt (10–7) to save his tour card and advance to the Crucible.