Barcelona say they signed left-back Junior Firpo from rival Spanish club Real Betis for a fee that could reach 30 million euros (33 million dollars).
Barcelona said that the 22-year-old Firpo has agreed to sign a five-year contract and will have a buyout clause of 200 million euros.
Firpo will provide a backup to regular starter Jordi Alba, who did not have any direct competition last season.
Born in the Dominican Republic, Firpo arrived in Spain when he was six years old and has Spanish nationality. He helped Spain win the Under-21 European Championship in June.
He joined Betis' youth academy in 2014 and debuted with its first team in 2018.
Barcelona witnessed Firpo's ability to join the attack when he scored the opening goal of a 4-3 win by Betis at Camp Nou in November, the only home loss suffered by Lionel Messi's side in the league last season.
In a statement, Barcelona said Firpo "provides the team with a dangerous" threat to defences and that "his height, speed and ability to pressure passers make him one of the most promising talents at the position of left-back" in football.