The 25-year-old Argentine suffered the injury in Rangers 1-1 draw in their FA Cup Third Round tie at Milton Keynes Dons.
His injury means he will not feature in the immediate plans of the successor to Neil Warnock who was sacked as manager on Sunday.
Faurlin confirmed the injury on his Twitter account, saying: "I just wanna let u know guys, its bad news for me I have rupture of the ACL, I'm out for the rest of the season! Really disappointed, sad."
Faurlin joined QPR from Argentine club Instituto in the summer of 2009 and the deal was subsequently found to have breached some of the English FA's transfer rules.
QPR were fined for breaking the regulations, but did not suffer a points deduction as they feared and were promoted to the Premier League at the end of last season as Championship champions.
Get the best features, fun and footballing frolics straight to your inbox every week.
Thank you for signing up to Four Four Two. You will receive a verification email shortly.
There was a problem. Please refresh the page and try again.