Baptistao, who completed his transfer to Madrid at the start of June, said that he hopes to continue to learn while he is at the club.
"Today is an important day for me," he told Marca. "I am very excited to have signed for Atletico Madrid. "It's a dream to play in a great team with great quality.
"It is a dream come true. For a boy of 20 years, this has happened to me very fast: the debut, goals, and move to a big team.
"I come eager to learn and to win. I'm very young and I will bring a lot to the club. I do not think about the pressure. I'm very young and I will learn a lot at this club."
The Brazilian scored seven goals for his previous club Rayo Vallecano last season.