Administrator Brendan Guilfoyle said in a statement: "It is with great disappointment I have to confirm Neil Warnock, Keith Curle and Mick Jones have left Crystal Palace FC to join QPR.
"I can assure all members of the Red and Blue Army as well as all of the club's stakeholders I did everything I could to persuade Neil to stay.
"However, further to an approach from QPR, Neil expressed his desire to leave and explained his focus was no longer on securing the club's status in the Championship. At this point, along with my legal advisors DLA Piper a compensation package was agreed with QPR."
Hart has been appointed manager until the end of the season. He has been Forst and Portsmouth manager in the past and ironically was Q.P.R. manager for just five games leaving in January.
He is now charged with keeping Palace in the Championship.