The 2012–13 season began very well for Campbell as he qualified for the Wuxi Classic, where he reached the first ranking event semi-final of his 21-year professional career. He dispatched Stephen Lee, Fergal O'Brien and Mark Williams to play Ricky Walden in the semis.&lt;ref name="2012/13"&gt;&lt;/ref&gt; He lost the match 1–6 and stated afterwards that he "didn't feel comfortable at all" and put it down to nerves. However, he also felt that winning a ranking tournament was now within his reach. He qualified for four of the next seven ranking events, but lost in the first round on each occasion. He had his best run of the season since Wuxi at the China Open where he overcame Peter Ebdon 5–3 and Graeme Dott 5–4 to make the quarter-finals. There, Campbell lost 2–5 to Neil Robertson. Campbell qualified for the World Championship with a 10–4 victory against Liam Highfield and played defending champion Ronnie O'Sullivan in the first round, who had taken a year away from snooker since lifting the title 12 months previously. Campbell missed opportunities in the first session to finish it 2–7 behind and went on to lose 4–10. Campbell was ranked world number 28 at the end of the season.