Costa will return to the Spanish Primera Liga in January, after four years in England, where he has won two Premier League titles and the EFL Cup with Chelsea.
While the €65m deal will go through in the coming days, the Brazilian born striker won’t be able to represent Atleti due to their transfer ban that ends in the new year.
Despite Costa’s troubles in London with manager Antonio Conte, the forward who went AWOL to force a move to the Estadio Wanda Metropolitano, scored 20 goals in 36 league games last season that saw Conte win the Premier League in his debut campaign.
“I’m very happy. It’s taken a long time, but it’s had a happy ending,” he told reporters in Madrid. “Now I’ll wait to see my teammates and train. Desire is something that I won’t have a shortage of.
“I wanted to come back here, but I won’t be ungrateful to Chelsea, where I was also very happy there, playing for a team that were very big.
“Still, Atletico are my home and here I am. Leaving Chelsea on a bad note? It’s not something I wanted, not at all,” the 28-year-old added.
“I have a special affection for the Chelsea fans. I’m not a person who’d tarnish an image. They know the person I am, but I’m here now and that’s a different issue.”