Barton hopes to continue progression
"It is always quite weird when your contract is about to run out and you never know what the future holds," he told the Evening News.
"To get it signed and out of the way is a relief because I can concentrate on helping to push Manchester City forward like the rest of the playing staff. I always wanted to stay here. It was just a question of me putting pen to paper."
The 22-year-old, who scored in the midweek Carling Cup win over Barnsley, now hopes to continue the development he has gradually made since his debut at Bolton 18 months ago.
He added: "I've grown up a little bit more as a man and matured a bit more as a person. I think that has helped me a lot. The test now comes in the rest of the season."