The Brazilian full-back, who can play on either side of the back four, has
played 53 first-team matches for the Red Devils but has rarely been a
first-choice starter.
He will now have the chance to push for consistent senior football at Loftus
Road.
Fabio joined United from Fluminense alongside twin brother Rafael - who today penned a new four-year deal at Old Trafford - in August 2008.
The 21-year-old's arrival has been hailed by Rangers boss Mark Hughes,
"It's a great opportunity for us to loan a good, young player, who has decent experience of playing for a top club like Manchester United," he told the club's website.
"He's played a lot of senior games for United, so it shows the quality he's got.
"I know they think very highly of him and we believe he has all the attributes to be a success here next season.
"First and foremost, he's a good defender. He's got great enthusiasm as well, and just like his brother, he's a top professional.
"We can give him the games he's craving at this stage of his career, so it benefits everybody.
"He's very versatile - he can play left or right-back and he's also been utilised in midfield by Sir Alex (Ferguson) in the past, so we know what we're getting, and that's a very good player."
Fabio sees the move - and the chance of establishing himself in the Barclays Premier League - as important to his development.
"I'm so happy to be here," he said. "This loan is so important for me in terms of my career. I want to play as many games as possible here. I want to play well and win games as well.
"It's a good move for my career and for my confidence.
"Sir Alex Ferguson said that I'd enjoy it here and told me to play as many games as I can. I know that QPR is a club with great history. I read about the history and that's why I'm here.
"I also came here because I'm ambitious. I want to help QPR progress up the Premier League.
"Hopefully the fans will enjoy watching me in action, because I'll do my best."
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