The 61-year-old becomes the club's fifth manager of the season but, following Flavio Briatore's departure as chairman, is hoping his arrival will herald a new era of stability.
Warnock, who has signed a three-and-a-half-year deal, said: "It's something I didn't envisage over the last couple of years but this has always been a great football club.
"Although I thought the contract was three and a half weeks!
"Stability has not been around this club for a while but it's the right challenge at the right time for me. All I want is a chance.
"I want to stabilise this season and then take the club on. Everyone knows I want to manage in the Premier League and I don't think there are many clubs coming in for me."
New chairman Ishan Saksena is keen to steer the club away from the revolving door of managers under Briatore.
"QPR has a history of being a family club so I want to welcome Neil as the latest member of the QPR family," he said.
"It is important to bring back stability - he will bring that back and lead the way in a bright future for the club.
"He is the complete package as a manager and was always our number one choice."
West Brom 11/10, Draw 9/4, Q.P.R. 5/2