Rafinha has signed a one-year contract extension at Barcelona and completed a loan move to Celta Vigo.
The Brazil international, 26, who has featured in all three of Barcelona's games so far this season, had entered the final year of his existing deal at the Nou Camp.
His new contract takes him up to the end of the 2020-21 season but he will spend the rest of this campaign at Celta Vigo.
A statement on Vigo's website said: "FC Barcelona and Rafinha have agreed on the renewal of the player's contract through to the end of the 2020/21 season.
"Additionally, Barca and Celta Vigo have come to an agreement whereas Rafinha will play at Celta on loan for the 2019/20 season. Celta thus take on Rafinha's salary plus potential add-ons of up to 1.5million euros.
"FC Barcelona would like to publicly express its gratitude to Rafinha for his commitment and dedication, and wishes him the best of luck and continued success."