O'Sullivan began the 2011–12 season at Event 1 of the Players Tour Championship, where he won 4–0 in the final against Joe Perry. At the Paul Hunter Classic, he made the 11th official maximum break of his career, and set a new record of career maximum breaks. He reached the semi-finals, but lost 3–4 against Mark Selby. His next tournament was the Shanghai Masters, where he reached the second round, but lost 3–5 against Anthony Hamilton. In October 2011 he won the Kay Suzanne Memorial Trophy, by defeating Matthew Stevens 4–2 in the final. In November 2011 he reached the final of the Antwerp Open, but lost 3–4 against Judd Trump. After 12 of 12 events, O'Sullivan was ranked number two on the Order of Merit, and qualified for the Finals, but withdrew due to medical reasons.