Paul Pogba said “the time is right to go back to Old Trafford” after completing his world-record £89m transfer to Manchester United.
The 23-year-old midfielder returns after four years away, having left United for Juventus for £1.5m in 2012.
Pogba, who signed a five-year deal, added: “This is the right club for me to achieve everything I hope to.”
Manager Jose Mourinho said the France international could be “the heart of the club” for the next decade.
United will pay the Italian champions 105m euros for Pogba, plus 5m euros (£4.5m) in performance-related bonuses and other costs, including 5m euros if Pogba signs a new contract.
It surpasses the £85m that Real Madrid paid Tottenham for Wales forward Gareth Bale in 2013.
Pogba, who helped hosts France reach the Euro 2016 final, has won the Serie A title in each of his four seasons at Juventus.
He is Mourinho’s fourth signing at United, after Ivory Coast defender Eric Bailly, Swedish striker Zlatan Ibrahimovic and Armenia forward Henrikh Mkhitaryan.
It will be the first time in 20 years an English club has set a world-record transfer fee, after Newcastle United paid £15 to sign England striker Alan Shearer from Blackburn Rovers for £15m.
Pogba joined United from French club Le Havre in 2009 as a 16-year-old, but made just a handful of appearances before his contract expired in July 2012.