Arsenal and Manchester United have confirmed Alexis Sanchez’s move to Old Trafford in an exchange deal involving Henrikh Mkhitaryan.
Chile forward Sanchez, 29, has signed a four-and-a-half-year deal.
It comes after months of speculation over his future as his Arsenal contract was due to expire at the end of the season.
He had been tipped to join Manchester City, who opted not to pursue their interest in him, paving the way for United to snap him up.
Midfielder Mkhitaryan, 29, moves in the opposite direction to after scoring 13 goals in 63 appearances for United.
“I am thrilled to be joining the biggest club in the world,” Sanchez told United’s website.
“I have spent three-and-a-half wonderful years at Arsenal and I bring with me very positive memories of that great club and its fans.
“The chance to play in this historic stadium and to work with Jose Mourinho was something I could not turn down.
“I am very proud to be the first Chilean player ever to play for United’s first team and I hope I can show our fans all around the world why the club wanted to bring me here.”
Sanchez faced criticism, including from high-profile former Arsenal players, over his conduct during his final months at the Emirates Stadium.
However, in a post on Instagram, he thanked Arsenal and hit back at “former club players who have spoken with no knowledge of what happens inside the club and cause damage”, insisting he has always shown commitment to the Gunners.
Mkhitaryan, meanwhile, told Arsenal’s website: “I’m very happy that we could finish this deal and I’m very happy to be here.
“It’s a dream come true because I’ve always dreamed of playing for Arsenal. Now that I’m here, I’ll do my best for this club to create history.”