"I'm very, very happy," he told MUTV. "It's a big moment for me. I waited for a long time, I've worked hard for this and I'm very happy to join this big club, this great club. I hope to do everything for this club."
"I am thrilled to sign for Manchester United. I have known the manager (David Moyes) for many years now and I have a lot of respect for his way of working. When I was given the opportunity to work with him again, I jumped at the chance.
"I had a fantastic time at Everton and I'd like to thank all the fans and staff there for everything they have done for me. But being a Manchester United player is something that every player dreams of and I believe that I can make a real contribution to the team's efforts to win trophies in the future."
United are reported to have paid Everton a transfer fee of £27.5m.