The 33-year-old Republic of Ireland international has penned a one-year deal at Loftus Road.
The centre-back recently left Villa Park following a four-year spell with the Midlands club.
"I've been very close to signing for Harry [Redknapp] on a couple of occasions and the opportunity to work with him really appealed to me," Dunne told QPR's official website. "Players want to play for Harry and I'm no different.
"I know the club didn't have a good season last term, but – having spoken to Harry, as well as [owner] Tony [Fernandes] – there's a real determination to bounce back into the Premier League, which is where we all want to be."
Dunne will join the QPR squad on Tuesday when they fly out to Austria to continue their pre-season preparations.