The new four-year deal will keep the 21-year-old at Old Trafford until the summer of 2016.
United boss Sir Alex Ferguson told the club’s official website: “Rafael is one of the club’s brightest young prospects; he has no fear of playing and has great belief in himself.
“The boy has developed immensely since joining United, his energy and enthusiasm are a joy to watch. Rafael has all the attributes to become one of the best full-backs in the world and I am delighted he has signed a new contract.”
Rafael added: “I am so happy to sign a new contract. I love playing for Manchester United, there is a great team spirit here and a real desire to win.
“My time here has been unbelievable; winning two league titles, a league cup and a Club World Cup has made me hungry for more trophies. I would like to thank Sir Alex for his belief in me and I would also like to thank the fans for their support.”
