Chelsea have signed João Félix on a permanent transfer from Atlético Madrid, the London club announced on Wednesday.
The forward has put pen to paper on a seven-year contract.
Sources have told ESPN that the clubs agreed a deal worth in the region of €50 million ($55.4m), including add-ons. Atlético will retain a 20% share of any future fee that the player generates in a transfer away from Chelsea.
It marks a return to west London for Félix, who spent six months on loan last season at Stamford Bridge, scoring four goals in 20 appearances.
"I'm really happy to be back at Chelsea and I can't wait to get started," Félix said. "I can see some familiar faces from the last time I was here, which is always nice.
"I loved my time here before and I told my friends and family that I'd love to return to the Premier League one day. To do that with Chelsea is a great feeling and I'm excited to be back."
Félix played last season on loan at Barcelona from Atlético and scored 10 goals in 44 appearances.
He had hoped to continue at Barça beyond this summer but returned to Atlético after playing for Portugal at Euro 2024.
The 24-year-old is Chelsea's 11th summer signing after Pedro Neto, Tosin Adarabioyo, Kiernan Dewsbury-Hall, Filip Jörgensen, Omari Kellyman, Aaron Anselmino, Caleb Wiley, Renato Veiga and Marc Guiu, with Estêvão Willian having agreed to join the club in 2025.
Félix, who began his career at Benfica, moved to Atlético in the summer of 2019 for a club-record €126m. He did not live up to expectations and struggled to adapt to head coach Diego Simeone's tactics. He scored scored 34 goals in 131 games for Atlético.