On 27 January 2010, Manchester United announced that they had signed Smalling, for an undisclosed fee, with the player staying at Fulham for the remainder of the 2009–10 season before joining United for the beginning 2010–11 campaign. The transfer officially went through on 1 July 2010. Smalling made his debut for United on 8 August 2010 in the 2010 FA Community Shield, appearing as a second-half substitute in a 3–1 win over Chelsea. His Premier League debut for United came in their 3–0 home win over West Ham United on 28 August 2010, coming on as a 74th-minute substitute for Jonny Evans. On 15 September 2010, he made his UEFA Champions League debut, playing the full 90 minutes in a 0–0 draw at home against Rangers. Eight days later, Smalling scored his first goal for Manchester United, also his first senior career goal, in a 5–2 away win over Scunthorpe United in the League Cup. Smalling then made his full Premier League debut for United on 4 January 2011, partnering Nemanja Vidić for the full 90 minutes in a 2–1 home win against Stoke City.