But that was only part of a transfer saga that looks set to rumble on after Atletico complained Barcelona should have paid €200million for the France forward, rather than €120m.
We look back at the long road Griezmann has travelled in order to finally join Barcelona on a five-year deal.
June 2017 – linked with Manchester United
Griezmann hit 16 LaLiga goals in the 2016-17 season and was subsequently linked with joining Premier League giants Manchester United. But after United's interest in the forward reportedly cooled and Atletico had a transfer ban upheld, Griezmann suggested he had decided to stay. At the time, €100m would have been enough to trigger the release clause in Griezmann's contract.
November 2017 – rumours pick up pace
Despite a slow start to the 2017-18 season, Griezmann continued to be linked with a move away from Atletico. Diego Simeone defended his lack of form with United, Paris Saint-Germain and Barcelona all said to be circling.
December 2017 – Atletico report Barca to FIFA
Soon after, it became clear Barca were at the front of the queue for Griezmann, but Atletico were already taking issue with the Catalans' transfer tactics. It came to a head when Atletico reported Barca for an alleged illegal approach. Barca's director of institutional and sporting relations Guillermo Amor had previously suggested the club's president Josep Maria Bartomeu may have met Griezmann to discuss a move.
January 2018 – Barca deny deal agreed
A report in Sport claimed Barca had agreed a deal to sign Griezmann at the end of the 2017-18 season. But Barca hit back, fiercely rubbishing the reports in a statement that read: "Barcelona strongly denies the information that has appeared over the course of the last few hours in different media regarding Atletico Madrid player, Antoine Griezmann, and an alleged deal with our club."
March 2018 – Simeone ignoring speculation
Only a few weeks later, there were widespread reports saying Griezmann had agreed a deal with Barca, but Atleti boss Simeone rejected the rumours. "I have to talk about realities," Simeone told reporters. "Today he is with us, he plays fantastically well and there is very good togetherness with the fans."
June 2018 – La Decision
After Griezmann's goals earned Atletico Madrid the Europa League title, downing Marseille in the final, speculation over his future reached fever pitch. He seemed certain to leave for Barcelona, but in a documentary made by Gerard Pique's Kosmos production company, he announced he would instead stay. Griezmann then signed a new contract with an improved release clause of €200m.
Early 2019 – Rumours build, La Decision II?
Griezmann fired France to World Cup glory after La Decision, but rumours he was going to leave Atletico simply would not go away. And, as the end of the season neared, it was reported Griezmann had another documentary planned in which he would mull over his future once again.
May 2019 – Griezmann goes public
In a video posted to social media, Griezmann confirmed his intention to leave Atletico, with production values in the hastily published clip a far cry from the previous year's La Decision. In his final appearance for Atletico, he was subsequently booed by unhappy supporters.
July 5 – Atletico release scathing statement
After a strangely quiet few weeks, Atletico accused Barca of prompting Griezmann to break his contract. Atletico claim they learned the forward and Barca had put an agreement in place as long ago as March, when his release clause was still €200m, while the club said they had been negotiating since mid-February. Griezmann's release clause dropped to €120m on July 1.
July 7 – Griezmann misses training
The transfer rapidly gathered pace as Griezmann failed to report for the first day of pre-season training with Atletico, who opened disciplinary proceedings against the player as a result.
July 12 – Deal finally confirmed
Five days later, Griezmann is a Barcelona player after the club deposited his release clause. He put pen to paper on a five-year deal to end his stay at Atletico. But the Rojiblancos immediately released a statement announcing the club are challenging the transfer. Because Atletico claim Griezmann and Barcelona had a deal agreed before his release clause was reduced, they demand €200m – €80m more than Barca paid. The saga is not over yet.