The 35-year-old, who was let go by the Red Devils at the end of last season, has been snapped up by the Londoners in a deal that will keep him at Loftus Road until next summer.
Speaking to QPR's official website, Ferdinand claimed that he had plenty of lucrative offers available but believes that he still has something to offer the Premier League.
"I spoke to Harry [Redknapp] and [owner Tony] Fernandes at length. I think they both looked me in the eye and knew that I still have something to offer – that I had a genuine desire to come here and play football," he said.
"I had a lot of offers from all over the world – some in places with a better climate than here. But the draw for me was to play in the Premier League and back here where it all started.
"It's not about money – I had loads of more lucrative offers available to me. I still feel I've got something to offer and I'm excited about helping this club cement its place in the Premier League."
The deal marks manager Harry Redknapp's first piece of business this summer, and the 67-year-old - who also managed Ferdinand at West Ham United - says that the signing represents a "remarkable coup for the club".
"Rio's a fantastic player and a great professional – I'm delighted we've been able to bring him here," added Redknapp.
"I signed Rio as a 14 year-old. He was class on the field and off the field then, and he's continued in that manner throughout his career.
"During his time at Manchester United, he was the best defender in Europe, if not the world. To bring him to QPR – when he's still got so much to offer in terms of his quality, class, experience and know-how – is a remarkable coup for the club."
Ferdinand won six Premier League titles and one Champions League in his 12-year spell at Old Trafford.