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 Pogba 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.
It surpasses Wales forward Gareth Bale’s £85m move to Real Madrid from Spurs in 2013 as the biggest transfer deal in history.
The announcement was made just after 12:30 am today, with a glossy video, showing the player, with a red devil marked into his hair, emerging dramatically from the shadows.
It was followed by a series of sponsor videos, including one with English rapper Stormzy.
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, former Sweden striker Zlatan Ibrahimovic and Armenia forward Henrikh Mkhitaryan.
It will be the first time in 20 years an English club has paid a world-record fee – England striker Alan Shearer’s move to Newcastle United from Blackburn Rovers for £15m was the last.
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.
He has made 178 appearances for Juventus, scoring 34 goals, and helped the club reach the 2015 Champions League final. The Serie A side had offered him a new contract, while Real Madrid were also interested in signing him.