Sterling is Chelsea's first signing this summer.
The England international has signed a five-year contract at Stamford Bridge after seven seasons in the blue half of Manchester.
Sterling signed for Manchester City for £49m from Liverpool in the summer of 2015 and the England international scored 131 goals in 339 games for the Citizens.
The 27-year-old won among other honours four Premier League titles and one FA Cup with Pep Guardiola's side.
Sterling paid a special tribute to his former club earlier on Wednesday before his move to Thomas Tuchel's side was confirmed.
'First and foremost, it's a pleasure to be here,' Sterling said after being unveiled in Los Angeles, where Chelsea are currently on tour.
'I've obviously achieved a lot in my career so far, but there is still so much more to achieve and I'm really looking forward to doing that in a Chelsea shirt, under Thomas (Tuchel's) management.
'London is my home and where it all started for me, and it's amazing I now have the opportunity to play in front of friends and family week in, week out at Stamford Bridge. I'm really looking forward to meeting the fans there soon.'
'I can't wait to get going now and continue to do my talking on the pitch.'
Chairman and co-owner Todd Boehly added: 'Raheem Sterling is a serial winner and his signing is an important step in strengthening our squad.
'We are delighted for Raheem to return to London with Chelsea, and we look forward to seeing his world-class talent on display at Stamford Bridge.'
Napoli defender Kalidou Koulibaly could soon join Sterling at Chelsea, with the Blues having reportedly agreed a deal to sign the Senegal captain.
