On 23 June 2011, Young completed a move to Manchester United for an undisclosed fee, reportedly between £15 million and £20 million, having passed a medical the day before, beating Liverpool to the signing.

He was handed the #18 shirt previously worn by Paul Scholes and made his debut for United in a 3–2 derby win over Manchester City in the 2011 FA Community Shield, playing the full 90 minutes and making an assist.

He made his league debut for United against West Bromwich Albion on 14 August 2011, setting up the first goal for Wayne Rooney and forcing an own goal after a run down the left flank and cross, in a 2–1 away win.

He was named man of the match. He scored his first two goals for United on 28 August in an 8–2 victory against Arsenal at Old Trafford.

On 7 August 2015, Young signed a new three-year contract with Manchester United, keeping him at the club until June 2018, with the option to extend a further year.