Cao qualified for the 2012 World Snooker Championship in his debut season after defeating Kurt Maflin 10–2, Dave Harold 10–9 (coming back from 6–9 down), Nigel Bond 10–7 and Tom Ford 10–9 in the qualifying rounds. At the venue stage he put in an outstanding performance beating Mark Allen (world number 11) 10–6 to reach the last 16. After the match, Allen accused Cao of dishonesty following what he perceived as a foul shot which Cao did not own up to when he was leading 5–4. Allen also said that "blatant cheating" might be "a bit of a trait for the Chinese players". Television replays of the incident proved inconclusive with Cao stating that he did not remember the shot as he was focusing on the game. Allen later apologised for his remarks, admitting that he had "overstepped the line". Cao played Ryan Day in his next match and trailed 7–9 going into the final session, when his opponent won four straight frames in just over an hour to result in a 7–13 defeat. Cao finished the season ranked world number 70, outside of the top 64 who retain their places on the snooker tour.