The 23-year-old Portuguese forward becomes Chelsea’s fourth January signing, after Benoit Badiashile, David Datro Fofana, and Andrey Santos. They have signed him on loan at a fee of €11m (£9.69m).
After being officially unveiled at the West London club, the youngster said: “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.”
Felix joined Atletico from Benfica in 2019 and was part of the team that won the Spanish La Liga two seasons ago.
He leaves Atletico with five goals and three assists across all competitions this season and will look to help Chelsea, who are struggling in the Premier League as they are now sitting 10th in the standings with 27 points from 17 matches.