The 57-times capped Republic of Ireland international striker, who moved to Molineux from Reading in 2009, has found first team starts limited in recent weeks for the League One club and jumps a division to join the Championship promotion chasers.
QPR lost top scorer Charlie Austin in midweek to a shoulder injury, which requires surgery, after the 2-1 victory over Bolton at Loftus Road and manager Harry Redknapp was quick to bring in a replacement.
Redknapp said: "I like Kevin. He's a good pro and a good lad who needs to get his career up and running again.
"He was a good player at Reading and my sides have played against him many times. This is a great opportunity for him. I like him a lot - he's a good player and a good person.
"He'll be a key addition to the squad."
Irishman Doyle, 30, said: "It was all agreed pretty quickly. I jumped at the chance to come here to be honest. The club's in a great position for a tilt at promotion and I can't wait to be part of it.
"It was a massive draw to know I'll be part of a promotion push and obviously the manager played a huge role in my decision to come here as well.
"The squad here have enjoyed a really positive first half of the season and everyone is looking forward to tomorrow.
"It's a big game and I'm just looking forward to hopefully being involved in some capacity."
Redknapp also confirmed the loan deal to bring another forward into the club, Will Keane from Manchester United, had been completed.
He told Sky Sports News: "He's got a great future and hopefully we can help him on his way. Thanks to David Moyes for the opportunity to bring him here."