The 24-year-old becomes the third City player to sign fresh terms in a week, following extensions for Phil Foden and Abdukodir Khusanov, as the club locks down its core ahead of Enzo Maresca's first full season in charge.
Since joining from RB Leipzig in 2023 for around £77m, Gvardiol has made 122 appearances and scored 13 goals, helping City to six major honours: the Premier League, FA Cup, League Cup, FIFA Club World Cup, UEFA Super Cup and Community Shield. He was also named the club's Player of the Year for 2024/25 and has won 52 caps for Croatia, featuring at the 2026 World Cup.
"As soon as I knew City wanted to renew my contract, I felt straight away it was what I wanted," Gvardiol said. "The City fans have been unbelievable with me from day one - and the club provide absolutely everything for players.
"It's the best club in the world to be at. I have felt so much love and respect during my three years here and I don't take that for granted. The players we have here are amazing. This is a world-class squad that is young and full of potential. I truly believe we will have a lot of success in the coming years."
Director of Football Hugo Viana said the defender's versatility and professionalism made the renewal a priority for the club.
"Josko is a player this Club really believes in. He is young, an outstanding professional and already one of the best defenders in the world," Viana said. "Manchester City are committed to keeping our best talent, which is why we are so happy this new contract has been agreed.
"Josko epitomises what we want in our defenders - he can play multiple positions, is quick, strong and when he attacks he does it superbly. He is exceptional. But the way he conducts himself is also very impressive. This is a young man determined to be the best he can be - an approach that is totally aligned with our overall vision."
Reflecting on his three years in Manchester, Gvardiol singled out the Premier League title as the most meaningful of his six trophies.
"I would say my favourite one and the most difficult one to win is the Premier League, especially because in my first season I gave an interview and said that only a few Croatians have won the Premier League," he said. "I did it in my first season somehow and that's my favourite one."
Now working under Maresca following Pep Guardiola's decade in charge, Gvardiol insists he still has plenty of room to grow: "I still think there are a lot of things to improve and learn but I'm only 24, I have enough time."