Earlier he was listed as a City player in their squad for the Champions League play-offs on the UEFA website – before the deal was announced by either club.
Stones has agreed a six-year contract.
It's reported City paid around 50 million euro for the former Barnsley player.
Manager Pep Guardiola says he likes the way Stones plays and the player himself told Manchester City TV he's glad to be working with the former Barcelona boss.
