"It's an honour for me to come here. It's a club that showed interest in me from the first moment and made me feel important in terms of their project," Traore said in a statement.
Villa manager Tim Sherwood said he was pleased to finally seal the Spaniard's signature having tracked him for a long time.
"He's physically a man -- and he has been for some time," Sherwood said of his 10th signing of the transfer window.
"He's a big powerful boy, very quick, dynamic and a maverick-type player. Those players are few and far between.
"We're delighted he has chosen Villa to continue his development."
Sherwood said summer recruit Micah Richards, now the club captain, is in his prime and hopes the defender can produce his best form for Villa.
"We're delighted to have Micah here and if he can reproduce what we know he's capable of, we're getting him in his prime," the former Totthenham Hotspur manager said.
"Micah's been outstanding since he's been here -- that's why he's got the armband on. He's a leader. He's got a good aura about him, the boys look up to him and he's doing it on the pitch. He leads by example there.
"He's vocal too, he's not afraid to share his opinion with them."
Villa, who opened their season with a 1-0 win at Bournemouth last week, host Manchester United later on Friday.
(Reporting by Shravanth Vijayakumar in Bengaluru. Editing by Patrick Johnston/Sudipto Ganguly)
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