The 21-year-old’s previous contract, which he signed as a teenager in 2023, was due to run out in 2027.
The possibility of a fresh long-term deal seemed highly unlikely earlier in the season after Mainoo, who requested to go out on loan last summer, fell out of favour with Ruben Amorim. His only start in the entire first half of the season came in the League Cup defeat to Grimsby Town in August.
The England international was returned to the starting lineup by Carrick once he replaced Amorim in the dugout and he has been an ever present ever since.
Carrick ‘over the moon’ with new Man Utd deal for Mainoo
Speaking at his pre-match press conference ahead of Sunday’s clash with Liverpool, the interim head coach said: “I’ve been hugely impressed with him since I’ve been here. I’ve known him for quite some time, in different capacities, so I’ve certainly been aware of him for a long time.
“He epitomises this football club. He is a young player who has come through the academy, is living and breathing the club, and has come through with real talent.
“The natural thing for him was to sign a new contract so everyone is over the moon with it, including me because I think he deserves it.”
