The striker, who saw a failed medical scupper a move to Hull City in July, has signed a three-year deal with the Rs and aims to win promotion to the Premier League
The 24-year-old has opted to join Harry Redknapp's side for an undisclosed fee after two successful years at Turf Moor, which saw him net 45 goals in 75 starts.
His addition marks the fourth new arrival of the close-season for QPR, who were relegated from the Premier League last season.
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"He’s scored goals wherever he’s played throughout his career and I’m very confident he’ll take his game to the next level with us.
"I’ve got no doubt that if we give him the right service he will score a lot of goals for us.
"He’s young, he’s hungry and he’s up for the challenge of helping us get out of this division."
The transfer represents the fifth move of Austin's career and he admitted he cannot wait to get going at Loftus Road, with a failed medical at Hull City scuppering a move to the Premier League.
"I'm really pleased to be here," the forward said.
"Harry spoke to me at length about the ambition of the club and the desire to return to the Premier League and that’s where I want to be as well with QPR.
"I'll come in, give my all and hopefully score the goals that ensure we have a memorable season."