The 28-year-old Argentine landed on his left knee in Wednesday's shock League Cup second round defeat at Burton Albion and was sent for a scan.
And the Premier League club revealed on Friday that the unfortunate Faurlin has suffered cruciate damage for a third consecutive season.
QPR's head of medical services, Peter Florida James, told the club's official website: "We're all absolutely devastated for Ale.
"It looked so innocuous on Wednesday night, so this has come as a massive blow for us all.
"The knee itself stayed pretty stable, but the scans have since revealed his ACL graft has ruptured.
"If he has a repair it will be a six to nine month injury, which is absolutely devastating for all concerned."
Manager Harry Redknapp was left to rue Faurlin's misfortune once again.
"We're all desperately saddened and disappointed for Ale," he said.
"He is a great man and player, and he's suffered terribly bad luck over the last few years with injuries.
"We will, of course, do everything we can to support him and help him back on the road to recovery."
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