Ronaldo said: “I am delighted. I spoke with Sir Alex Ferguson about my future and everyone knew that I wanted to stay.
“I am very happy at the club and I want to win trophies and hopefully we will do that this season.”
United boss Ferguson added: “It is fantastic news, it emphasises the point that Cristiano is happy here and that he is at the right club.
“He has a great relationship with the team, staff and the fans and he will go on to be one of Manchester United’s great players.”