The Portuguese star has arrived at Stamford Bridge on a six-month loan deal.
Chelsea have confirmed Joao Felix will wear their number 11 jersey until the end of the season.
The Blues managed to finalize a loan deal for the Portugal international despite interest from several other Premier League sides.
An €11m loan fee secures Felix’s services at Stamford Bridge until June. But there has been no disclosure of whether there is also a purchase option in the 23-year-old’s contract.
“Chelsea is one of the great teams in the world,” Felix told the club’s website after signing a six-month deal.
“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 becomes Chelsea’s fourth signing this winter, following the arrivals of David Datro Fofana, Benoit Badiashile and Andrey Santos.
The Portuguese star, who joined Atletico on a €126m deal in 2019, becomes Chelsea’s new No. 11. He follows the likes of Timo Werner and Alexandre Pato, who wore Didier Drogba’s legendary jersey at the club.
Graham Potter hopes to solve his side’s severe goalscoring problems by signing Felix. The Blues have slipped to the tenth spot in the Premier League after an awful run of results after the World Cup.