Rafael, 21, arrived at Old Trafford in the summer of 2008 and his performances for the first team have seen him called into the full Brazil squad.
Sir Alex Ferguson is delighted to have secured Rafael's services for a further four years and told ManUtd.com: “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.”
The man himself is just as pleased: “I am so happy to sign a new contract," Rafael told us. "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.”