Mensah re-joined Sunderland on loan for the 2010–11 season on 11 August. Mensah started Sunderland's first match of the season, a 2–2 draw against Birmingham City. However, injuries and the form of Titus Bramble and Michael Turner kept Mensah out of the starting line-up for most of the 2010–11 season. Nevertheless, he returned helped the side kept three consecutive in three matches between 5 December 2010 and 18 December 2010 against West Ham United, Fulham and Bolton Wanderers. However, during a match against Bolton Wanderers on 18 December 2010, Mensah suffered an injury in the 21st minutes, leading him to be substituted and was sidelined for a month. It was not until on 5 February 2011 when Mensah returned to the starting line–up, starting the whole game, in a 3–2 loss against Stoke City. However, he received a straight red card in a match against Liverpool on 20 March 2011 after a foul on Luis Suárez, although the card was later rescinded. But on 9 April 2011, Mensah suffered a Grade Two adductor tear just 11 minutes into Saturday's 3–2 home defeat by West Bromwich Albion, casting doubt on his future at Sunderland. Following this, Mensah was out of actions for three weeks until he made a return as an unused substitute in a 3–0 defeat to Fulham. Mensah made his return to the starting line–up, helping Sunderland win 2–1 against [[Bolton Wanderers F.C.|Bolton Wanderers on 7 May 2011. Mensah made his last appearance for Sunderland in a 3–1 loss against Wolverhampton Wanderers on 14 May 2011. At the end of the 2010–11 season, he made eighteen appearances in all competitions.