“Manchester United is delighted to confirm the signing of Harry Maguire from Leicester City,” the club said in a statement on its website.
“Harry signs on a six-year contract, with the option to extend for a further year.”
The England international, 26, was strongly linked with both Manchester clubs over the summer but Leicester held out for their valuation and the fee surpasses the £75 million Liverpool paid Southampton for Virgil Van Dijk in January 2018.
“I am delighted to have signed for this great club,” Maguire told United’s official website. “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.
“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 (Gunnar Solskjaer) is building a team to win trophies. I am now looking forward to meeting my new teammates and getting the season started.”