The 2012–13 season saw Poomjaeng qualify for the main draw of a ranking event for the first time. This came in the 2013 German Masters, by defeating Yu Delu and Fergal O'Brien. He lost 2–5 to Barry Hawkins in the first round in Berlin.&lt;ref name="2012/13"&gt;&lt;/ref&gt; Poomjaeng continued his form by winning four matches to reach the China Open. Once at the venue in Beijing, he saw off Zhu Yinghui 5–2 in the wildcard round, but then lost 3–5 to Mark Davis in the first round. In the Players Tour Championship events this season Poomjaeng's best results were last 16 defeats in the First and Fourth events, losing to Alan McManus and Mark Joyce respectively. He was ranked 42nd on the PTC Order of Merit. Poomjaeng beat Michael Leslie 10–4, Liu Chuang 10–9, Anthony Hamilton 10–4 and Jamie Cope 10–3 to qualify for the World Championship for the first time. He faced sixth seed Stephen Maguire in the first round and produced a huge shock with the world number 70 Poomjaeng winning 10–9, with a composed 63 break in the final frame. The crowd warmed to Poomjaeng as he walked to the wrong table at the start of play and animatedly expressed his emotions throughout the match, including applauding his own safety shot. He played Michael White in the second round and lost the fourth frame without a ball having been potted due to missing the reds three times. The rules of snooker state that if a red can be seen full ball and is missed on three consecutive shots, the frame is conceded. Poomjaeng lost the session 1–7 and went on to be defeated 3–13. His cheque of £16,000 for reaching the last 16 more than doubled his previous career earnings since turning professional in 2011. Poomjaeng finished the season ranked world number 67.