Carter made a slow start to the 2009–10 season, losing 0–5 to Liang Wenbo in the last 16 of the Shanghai Masters and losing in the first round at the Grand Prix, before reaching the quarter-finals of the UK Championship. As the defending champion at the Welsh Open he progressed to the final but was beaten by John Higgins, the reigning world champion at the time. He finished the season strongly by reaching the semi-finals at the China Open and the World Championship, losing in the latter to eventual champion, Neil Robertson, by 12–17. Of the six ranking tournaments that were staged during the 2009/2010 season, Carter's campaigns were ended by the eventual champion on four occasions, and on another by the runner-up. Carter finished the season by moving up to a career high position of 4th in the world rankings.