The France global has been linked with a mega-money move away from Atletico Madrid for several years.
However, in a video posted this evening by Atleti's official Twitter account, Griezmann has confirmed his time at the Wanda Metropolitano is over.
Barca look certain to be his next destination with Griezmann, 28, reportedly set on making a move he spurned previous year.
In a video lasting more than two minutes, the Frenchman thanked the fans for the affection shown towards him during his five years at the club, as well as explaining his decision for leaving.
The World Cup victor has been linked with Barça for over a year and was expected to sign for the Spanish champions last summer, before the transfer saga culminated in a remarkable U-turn, with the player announcing his decision to stay at Atletico in the now infamous televised documentary "La Decisión".
His departure from Atletico opens a massive vacancy up front for Diego Simeone, whose side is in for some major decisions in the coming months.
In the video, Griezmann went on to say that he chose to leave the club to seek a new challenge, and made the decision after a meeting with manager Diego Simeone and club CEO Miguel Angel Gil Marin.
"He's a very important player, who will become second captain", the Argentinian said.
"After speaking with Cholo [Simeone], then with Miguel Angel [Gil] and the people in the hierarchy of the club I wanted to speak with you, the fans, who have always given me a lot of love", he began. He also has 28 goals in 69 appearances for Les Blues.