The Portuguese club has acquired Pau Victor's services outright, paying €12 million for his transfer.
This deal includes an additional €3 million in bonuses for Barcelona.
Víctor, who is 22 years old, has signed a contract that will last until 2030.
The contract also includes a €50 million buyout clause.
In the 2024/25 season, Víctor played 29 games for Barcelona under coach Hansi Flick.
Of these, 21 games were in the La Liga league, where he scored two goals.
He also played six games in the Champions League and two games in the Copa del Rey.
