The 23-year-old England international joined the north-east club on a five-year deal earlier this week following two years at City during which he made just 16 first-team appearances.
Rodwell was considered one of England’s brightest prospects after impressing at boyhood club Everton and the midfielder hopes to recapture his best form.
“I started pre-season with Man City but always thought I should be signing for someone else,” he said.
“It’s been difficult. I struggled with injuries in the first season and didn’t have much playing time in the second.
“It was a great experience and a learning curve but disappointing at the same time. I wanted to play every week there but it didn’t work out like that unfortunately.
“But that’s football, you have to get on with it, and it’s a new chapter now and I’m glad to finally get the deal over the line and crack on.
“I can’t wait to start at Sunderland now. Hopefully I can get the minutes on the pitch and play week-in, week-out.”