Crystal Palace co-chairman Steve Parish felt he had no choice.
Just four months after beginning a second spell at the Selhurst Park helm, the 66-year-old has been relieved of his duties having failed to carry on the stellar work done by predecessor Tony Pulis.
The south Londoners slipped into the bottom three on Boxing Day after an embarrassing 3-1 home defeat to Southampton, during which supporters turned on Warnock.
Palace have acted swiftly to halt that alarming slide by sacking the Yorkshireman and putting Keith Millen in caretaker charge for the second time this season.
Crystal Palace co-chairman Steve Parish: "It just didn't gel. It didn't work. Keith is probably in charge for the next two games.
"We need a win. QPR is no bigger than any other but we need three points.
"Neil is a lovely bloke. He did everything he could.
"It's an unfortunate decision. I thought about it overnight and decided we needed a change. Hopefully we'll get a reaction from everybody."
Tim Sherwood is already the standout candidate to replace Warnock.
Sherwood is again in the running for a job he ruled himself out of in August, with the ex-Tottenham head coach saying he would have wanted to succeed Pulis had he been offered the position after his interview.
Malky Mackay, now in charge at Wigan, had been the favourite to succeed Pulis, only for allegations of misconduct to see Palace end their interest.