Warnock led Rangers to the Championship title last season, although a poor run of results has prompted owner Tony Fernandes to remove the 63-year-old from his post, with Mark Hughes thought to be in line to replace him.
Fernandes said: “This decision has been made in the best interests of the club and I can assure everyone that this is not a decision that was made lightly.”
Sunday’s club statement said on qpr.co.uk: “Queens Park Rangers Football Club has today parted company with Manager Neil Warnock.
“Warnock joined the club in March 2010, overseeing 84 matches in charge, winning 33, drawing 27 and losing 24.
“Last season, he successfully guided the club back to the Premier League for the first time in 15 years.
“The board’s commitment to retaining our Premier League status ultimately led to this decision. QPR assistant manager Mick Jones and first-team coach Keith Curle have also left the club.”
Warnock appeared to take the decision gracefully, having seen the Hoops grab a late equaliser at MK Dons in the FA Cup on Saturday.
“Obviously I’m very disappointed, but having achieved so much, I leave the club with a great sense of pride,” he said.
“I have enjoyed my time here more than anywhere else and the QPR fans have been brilliant with me – they deserve success.
“My biggest regret is that the takeover didn’t happen earlier, because that would have given me the opportunity to bring in the targets I’d pinpointed all last summer and probably given us a better chance to succeed in the Premier League.
“The board at QPR are hugely ambitious and I wish them every success for the future.
“I’ve been involved in the game a long time and I will be spending the immediate future with my family and friends before deciding my next career move.”