Mazraoui, 26, has won four league titles, three with Ajax and one with Bayern Munich. The full-back has made 28 appearances for his country and was a key part of the team that reached the semi-final of the 2022 FIFA World Cup.
Noussair Mazraoui said: “It’s an incredible feeling to be a Manchester United player, and I cannot wait to walk out at Old Trafford wearing the red shirt. I know that I’m joining the club at an exciting time; everyone I’ve spoken to has the same ambition for us to win trophies together and I can feel the determination to achieve that.