Maguire becomes both the most expensive defender in world football and Ole Gunnar Solskjaer’s third signing of the summer, following the arrivals of Daniel James and Aaron Wan-Bissaka.
United have been chasing Maguire for some time since the England international impressed in the 2018 World Cup, though he elected to stay in the east Midlands last summer.
The fee eclipses the £75m Liverpool paid to acquire Virgil van Dijk and the potential £77m fee Juventus recently splashed out to sign Matthijs de Ligt from Ajax.
“I am delighted to have signed for this great club,” Maguire said. ”I have thoroughly enjoyed my time at Leicester and would like to thank everyone at the club and the fans for their fantastic support over the past two seasons.
How will Manchester United line up with Harry Maguire?
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“However, when Manchester United come knocking on your door, it is an incredible opportunity. From my conversations with the manager, I am excited about the vision and plans he has for the team.
“It’s clear to see that Ole is building a team to win trophies. I am now looking forward to meeting my new team-mates and getting the season started.”
Solskjaer added: “Harry is one of the best centre-backs in the game today and I am delighted we have secured his signature.
“He is a great reader of the game and has a strong presence on the pitch with the ability to remain calm under pressure – coupled with his composure on the ball and a huge presence in both boxes – I can see he will fit well into this group both on and off the pitch.
“He has a great personality and is a fantastic addition to the club. I would like to welcome Harry to Manchester United and we are looking forward to working with him as we prepare for the new season.”
During a protracted series of negotiations, Leicester were still holding out for a £90m fee for Maguire last week until an agreement was reached with United on Friday morning.
Maguire will fill the vacant No 5 shirt at Old Trafford and partner Victor Lindelof in the centre of United's defence. Solskjaer views him as the ideal player to strengthen a defence which conceded 54 goals last season, their worst-ever Premier League total.
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