Atletico Madrid on Monday said they had signed 19-year-old striker Samu Omorodion from Granada.
The Spain under-19 international joins on a five-year contract. Spanish media reported Atletico had activated the striker's buyout clause of six million euros ($6.5 million).
Omorodion, born to Nigerian parents, made his league debut for Granada in their season opener on 14 August against Atletico and scored the team's goal in a 3-1 loss.
"We saw the boy play the other day, we saw him in the friendlies, he has interesting things, he has potential," Atletico coach Diego Simeone said on Saturday.
Granada play their second game of the season at home to Rayo Vallecano later on Monday.
On their website on Monday, Atletico said Omorodion "is a physical prodigy with great coordination despite his 1.93m height. He stands out with his explosiveness, he is very fast and has goals in him."
Spanish media reported that Atletico plan to loan him out this season.
