The full-back has ended a seven-year spell at the Etihad, joining the Serie A club on a deal until the end of the 2019-20 season
Roma have completed the signing of Aleksandar Kolarov from Manchester City for €5 million.
The left-back has signed a three-year contract with the Serie A club that will run until June 30, 2020.
His exit from the Etihad Stadium ends a seven-year association with City for the Serbia international, who won two Premier League titles, two League Cups and the FA Cup in his time in Manchester.
"When I came in 2010, honestly, I didn't expect to play so long," Kolarov told City's official website.