Ledley played in Celtic's first game of the 2011–12 season, a 2–0 win over Hibernian. On 13 August he scored in a 5–1 win over Dundee United. On 10 September, he scored in a 4–0 victory over Motherwell. He then played in Celtic's 2–0 Europa League defeat against Atlético Madrid, but was left out of the first Old Firm match of the season. He was back in the team for Celtic's 2–0 Scottish League Cup victory over Ross County. On 24 September, he opened the scoring in Celtic's 2–0 win over Inverness. Five days later he started in Celtic's 1–1 draw with Italian team Udinese. He played at left back but had to come off at half time due to a groin injury. On 21 October, he scored a clever backwards header from a free-kick to give Celtic a 1–1 draw against Stade Rennais.