The 33-year-old left the reigning English champions after captaining them to a heroic Treble during the 22/23, opting to join Barcelona but only spending a season in Spain.
A return to City never looked on the cards, but Barcelona's ongoing financial crisis meant they needed to raise funds and Gundogan's transfer back to the Etihad was straightforward.
Gundogan and his wife, Sara, have settled back into their former surroundings with ease and are now expanding their family with a second child on the way.
Announcing the news of their second child, Gundogan posed with his wife and 18-month-old son, Kais, as floods of support poured in for the couple from friends and City fans.
Ilkay Gundogan and his wife, Sara, have announced they are expecting their second child together
Gundogan recently explained his happiness at being back at City in an exclusive interview with Mail Sport's Football Editor, Ian Ladyman, and revealed he is seeking perfection in all aspects of his life.
‘Perfection… well I just think it’s important to target it and I do,’ Gundogan says.
‘Believe it or not, even in training sessions I still get nervous. If we play a Rondo or a box game – five versus two or six versus two - I don’t want to make any mistakes you know? I don’t want to misplace a pass. And I am nervous about that.
Gundogan and his wife, Sara, have already has a son together and are now expecting again
‘It keeps me awake and on my front foot. It helps me get to a certain level and stay there. Maybe that’s another reason why I can play with these great players.’
City boss Guardiola has been keen to thrust Gundogan back into his most important plans with the five-time Premier League winner, playing 90 minutes in Sunday's fierce draw against title-rivals Arsenal and featuring in the club's Champions League opener.
He is yet to open his goalscoring account for the season but has been presented with key goalscoring opportunities against Atalanta and the Gunners, but was unable to convert any of those.
His presence in City's engineroom could now grow to be even greater after Ballon d'Or nominated midfielder Rodri suffered a long-term injury against Arsenal.