Ilkay Gundogan says it has been a "total privilege and pleasure" to play for Manchester City after joining Barcelona on a free transfer.
Gundogan was offered a new deal by City but will instead move to the Spanish champions on a two-year deal, with the option to extend for another year.
The 32-year-old's contract with City expires at the end of June.
"Manchester has been my home and I have felt part of a very special family at City," the Germany midfielder said.
Gundogan played 51 games in 2022-23, scoring 11 goals, as he played a key role in City winning the Treble.