Adnan Januzaj has joined Real Sociedad from Manchester United on a five-year contract in a deal believed to be worth around £9m.
Sky Sports News HQ revealed in June that Manchester United were considering a bid from the La Liga side for the 22-year-old.
Januzaj was not included in Jose Mourinho's squad for their pre-season tour of the United States and the deal to take the forward to San Sebastian is understood to include buy-back and sell-on clauses.
A statement on the United website read: "Adnan Januzaj has completed a transfer to Real Sociedad, Everybody at Manchester United wishes Adnan well for the next chapter of his career."
Januzaj made 27 appearances during his debut season under David Moyes in 2013/14, but has since been sent out on loan by Louis van Gaal and Mourinho.
In a message posted on social media, Januzaj paid tribute to 'some' of the Old Trafford staff but insisted he will always be a fan of the club.
He said: "I want to say a massive thank you to all my teammates that have come and gone from the club. It's been a pleasure to play with you all.
"Thank you to some of the coaches and staff that work at Manchester United to make it such a great club!
"Unfortunately, my time at the club has come to an end and it didn't go the way I wanted it to go but I will always have love for Manchester United.
"And finally, a huge thank you to the fans that have stuck by me through the good and bad time! I will never forget that positive support."
He linked up once again with Moyes at Sunderland last season, joining on a season-long loan, but did not manage to score in 25 appearances as they were relegated from the Premier League.
Januzaj also spent time on loan at Borussia Dortmund in 2015.