Turan, 28, was closely followed by both Chelsea and Manchester United this summer but Barcelona have won the race for his signature.
A statement from their website read: “Barcelona and Atletico Madrid have reached an agreement for the transfer of… Arda Turan.”
Turan will not be able to play for Barcelona until 2016 due to a transfer embargo on the Nou Camp club.
Turkey international Turan joined Atletico from Galatasaray in 2011 and helped the club win the Liga title in 2014.
Atletico have agreed to sell Arda Turan to Barcelona
The ace was tipped to join United after manager Louis van Gaal promised he would go after midfield players in the transfer window.
Chelsea were also keen suitors of the player, who was reportedly lined up in a swap deal that would have seen defender Filipe Luis head back to Atletico.