Ilkay Gundogan is back with Manchester City after the Premier League champions resigned their former captain on Friday on a one-year contract.
The 33-year-old German left City for Barcelona in 2023 on a free transfer after leading Pep Guardiola's team to the treble.
Gundogan could be available for Saturday's match against Ipswich Town at the Etihad Stadium.
"My seven years at Manchester City were a time of pure contentment for me, both on and off the pitch," Gundogan said.
"I grew as a person and a player, developed a special relationship with the City fans and enjoyed amazing success. It was an exceptional period in my life. To have the opportunity to return here means so much."
Gundogan returns won 14 major trophies with City, including five Premier League titles and the Champions League.
Although he had been under contract at Barcelona for two more years, he was told the club would not stand in his way if he wanted to leave.
"After just one year it's already time to say goodbye," Gundogan said in a social media post.
"I came here to face a new, exciting challenge, and I was ready for it. I have given everything to fight for the team and the club the best possible way in a difficult season.
"Now I am leaving in a difficult situation, but if my departure can help the club financially, it makes me a bit less sad."
Gundogan made 51 appearances last season, helping Barca to a second-place finish in La Liga.
His return is welcome for City side who sold Argentina forward Julian Alvarez to Atletico Madrid and are without winger Oscar Bobb for up to four months after the Norwegian broke his leg in training.
Gundogan joined City from Borussia Dortmund in 2016, scoring both goals in City's 2-1 win over Manchester United in the 2023 FA Cup final, including the quickest in FA Cup final history, inside 13 seconds.
He scored 60 goals in 304 appearances for Guardiola's side.
Gundogan recently announced his retirement from international soccer after 82 appearances, captaining Germany at Euro 2024.
