The former German international won five Premier League titles and the Champions League among 12 major trophies during his first spell at City between 2016 and 2023.
Gundogan departed the English champions just over a year ago to join Barca.
However, the 33-year-old and the Catalan giants reportedly agreed to rescind his contract after just one season to pave the way for a return to the Etihad.
In his sole season in Spain, Gundogan scored five goals and provided 14 assists but Barca failed to win a trophy.
“I am incredibly happy. Happy to see the teammates, the staff, people that over seven years I had an amazing time with, a very successful time with. Many ups, and a few downs, but in general, an incredible experience.
“When you leave this place like I did last year, you spend a year away, and you then start to appreciate the place even more. You realise what you had. You realise how amazing that time was. You realise how big the club is — the best club in the world,” Gundogan said in a City statement.
Gundogan’s return is a timely boost for City after the departure of Julian Alvarez to Atletico Madrid for a reported fee of up to 95 million euros (£81 million, $104 million).
He was Pep Guardiola’s first signing when both joined the club in 2016.
Gundogan went on to score 60 goals in 304 appearances and will provide experience and depth to Guardiola’s squad as they go for a record-extending fifth consecutive Premier League title.
“Ilkay is one of the finest professionals I have ever worked with. His dedication to football and his approach to every single training session is something special,” said City’s Director of Football Txiki Begiristain.
“To be able to bring him back here is fantastic news for everyone. He will help us in our main objective, which is to win trophies, but he will also be an inspiration to so many,” Begiristain added.
Gundogan is City’s second signing of the transfer window after the arrival of Brazilian winger Savinho.
AFP
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