QPR agreed on a compensation with Crystal Palace for the 61-year-old.
Warnock has signed a three-and-a-half-year contract with Rangers.
“I am delighted to be joining a club with the history that QPR has,” Warnock told the club’s official website.
“As a manager, Loftus Road is always a place I loved because of the fantastic atmosphere there.
“Looking from afar, I believe this is the perfect time for me to come in, with the new structure and chairman in place.
“Together we can give the club the stability that it needs. I am really looking forward to the challenge that’s in front of me.”