His season was generally pretty quiet, with his best ranking finish being reaching the last 16 at the World Open, where he was eliminated 5–1 by Kyren Wilson. 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). Drawn against John Higgins in the first round (who subsequently went on to reach the final), he recorded two century breaks but ultimately lost out 10–7. He finished the season ranked 56th. 2018–19 season 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. Un-Nooh then secured his first ranking event title at the 2019 Snooker Shoot Out, beating Michael Holt with a break of 74. This came after he made the highest break in the tournament's history, 139, in the semi-finals to beat Jamie Clarke. He secured a £32,000 prize and became the second player from Thailand to win a ranking event. He once again qualified for the World Championship, recording victories over Johnathan Bagley, Mark Joyce and Joe O'Connor. He was drawn against eventual champion Judd Trump in the first round, and lost 10–9 in a classic match, despite being 6–3 up and having a chance to win in the deciding frame. 2019–20 season 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. He also added another title by winning the non-ranking Haining Open, defeating Li Hang 5–3 in the final. 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. Facing Judd Trump, he fell 7–1 behind including conceding a frame after three fouls, but rallied to 8–5 before Trump took the remaining two frames. He picked up £75,000 for reaching the final which is his highest single-event prize to date. He also reached the quarter-finals of the Scottish Open where he lost out 5–3 to Jack Lisowski in an entertaining match, the European Masters where