Felix told the club’s official website: “Chelsea is one of the great teams in the world and I hope to help the team reach their objectives, so I am very, very happy to be here and very excited to play at Stamford Bridge.”
Atletico also confirmed that the forward extended his contract with the LaLiga for a further season, until June 2027.
“From Atletico de Madrid we wish Joao Felix every success in this new professional stage,” Atletico said in a statement.
Felix, 23, joins as Chelsea continue to struggle in front of goal, having scored the fewest goals in the Premier League top half.
Felix began his career at Benfica, where he quickly became a phenom, making his senior debut in 2018.
In July 2019, Atletico signed Felix for a club-record €126m — Atletico chief executive Miguel Angel Gil Marin said in December it was the “biggest bet” the club has ever made — but the forward struggled to make a significant impact.
He has scored 34 times in 131 games for Atletico — including five goals in 20 games in all competitions this season.