Barcelona sign Man City's treble-winning captain Ilkay Gundogan
The German midfielder, 32, has agreed a two-year deal with the option for a year's extension and a release clause of €400 million (£342 million).
"He is bringing his presence, nose for goal and reading of the game which has made him one of the best midfielders of the past decade," said Barcelona in a statement.
Gundogan has been an influential presence for Pep Guardiola's City side since joining in 2016, captaining the team to a stunning treble this season.
The midfielder netted twice in the FA Cup final win over rivals Manchester United and Guardiola admitted City were trying to renew his deal.
Manchester City are poised to seal the arrival of Mateo Kovacic from Chelsea to help replace Gundogan, who won five Premier League titles during his time at the club, as well as helping them earn their first-ever Champions League win this season.
Gundogan joined City from Borussia Dortmund, where he won the Bundesliga and German Cup in 2012.
"This club made me realise all my dreams and I will forever be thankful for this opportunity," Gundogan told Manchester City's club website.
"I will carry City always in my heart. Once a blue, always a blue."
Gundogan was the first signing Guardiola made after arriving at City, joining for around £20 million.
He moved to City from Borussia Dortmund, where he won the Bundesliga and German Cup in 2012.
Gundogan scored 60 goals in 304 appearances for the club, winning 12 major trophies.
"Ilkay has been tremendous, absolutely tremendous," said City chairman Khaldoon Al Mubarak.
"To be the captain of this club in this historic treble, lifting the Premier League first and then the FA Cup and then the Champions League, he will go down in the folklore of Manchester City forever."
City's director of football Txiki Begiristain highlighted Gundogan's mental attributes.
"Ilkay's intelligence, leadership and commitment to the club -- both on and off the field -- has been an inspiration to everyone," said Begiristain.
New adventure
Barcelona's new signing bolsters a midfield with plenty of options, including young Spaniards Pedri and Gavi, and Dutchman Frenkie de Jong.
However coach Xavi Hernandez has said the club still need to sign a defensive midfielder after captain Sergio Busquets left for Inter Miami at the end of his contract.
Barcelona moved for Gundogan after failing to secure the return of Lionel Messi at the end of his deal with Paris Saint-Germain.
The club's all-time record goalscorer and greatest-ever player was tempted by a return but finally opted to join Inter Miami, with Busquets following him there.
Gundogan turns 33 in October but finished the season in some of the most sparkling form of his career.
The midfielder netted six goals in his final seven games for City as he helped the club seal their treble, prompting them to make a final and ultimately unsuccessful effort to keep him.
"If he goes to Barça it would be an extraordinary signing, we're fighting for him to stay," said Guardiola last week.
"If he signs for Barça, I'll tell him that he will have a great time there."
