The 21-year-old Traore has joined the newly promoted west London club on a three-year contract.
He is the third signing since Air Asia chief executive Tony Fernandes took over at Loftus Road earlier this month, joining Joey Barton and Luke Young.
Traore has made 33 appearances for Arsenal and spent time on loan at Juventus last season.
“I’ve not been able to prove and show what I’m all about because I’ve been at two big, big clubs like Juventus and Arsenal,” he said. “I’m looking forward to coming here and playing regular football. The ambition of the new owners and the caliber of players they are signing is something that really attracted me to the club.”
QPR manager Neil Warnock has promised Traore regular action.