City confirmed Grealish’s capture on Thursday evening (UK time), having courted the England international in recent times.
Grealish arrived back in England earlier this week after a holiday following Euro 2020 and had trained at Villa, before heading to Manchester to complete the deal on Thursday.
“I am incredibly happy to have joined Manchester City,” Grealish said.
“City are the best team in the country with a manager considered to be the best in the world its a dream come true to be part of this club.
“Over the past 10 seasons, they have won major trophies consistently. Pep coming here has taken them to the next level and the football this team plays is the most exciting in Europe. To play for Pep and learn from him is going to be special and its something any top footballer would want.”
Pep Guardiola’s side have won three Premier League titles in the past four seasons, while they also won the 2019 FA Cup and the League Cup in four consecutive seasons.
But City have long wanted European glory, missing out as runners-up in the 2020-21 UEFA Champions League to Chelsea, having made the semi-finals in 2019-20.
City Director of Football Txiki Begiristain said: “He is an incredible talent. Jack’s development over the past few seasons both for club and country has been plain for everybody to see.
“His natural talent together with his commitment to improve as a player, has seen him become one of the most exciting attacking players in world football today.
“I am certain that the fans are going to love seeing him in our team. Pep loves the way he plays, and we all feel he is an ideal fit for Manchester City. Our style and his style are a perfect match. I’m excited to watch him over the coming years.”