International player Raheem Sterling became Chelsea's first deal since it was acquired by a consortium led by American Todd Boehle, ending a seven-year era at Manchester City.
"England star Raheem Sterling has joined Chelsea from Manchester City on a five-year contract," the Blues club said in a statement on their website.
Sterling tweeted his farewell message: "Seven seasons, 11 major titles, a lifetime of memories. What a path!"
The player continued, "I arrived in Manchester at the age of twenty. I am leaving today as a man. Thank you for your sincere support. It was an honor to wear the Manchester City shirt."
Sterling is currently accompanying Chelsea on his preparatory tour in the United States, where he is currently turning his attention to success with German coach Thomas Tuchel.
"Obviously I have achieved a lot in my career so far, but there is still a lot to achieve and I am really looking forward to doing it in a Chelsea shirt, under Thomas' guidance," he said in a statement.
"London is my home and where it all began for me and it is amazing now to have the opportunity to play against friends and family every week at Stamford Bridge."
According to Sky, the player, who has played 77 international matches, will move for 47.5 million pounds (about 56 million dollars), while the BBC spoke of a deal worth 50 million pounds (about 59 million dollars).
Sterling, 27, won the Premier League title four times with City since joining from Liverpool in 2015, and played a key role in the squad in his first season at the Etihad Stadium. Spanish coach Pep Guardiola's squad player scored 131 goals in 337 games for City.
His position in the blue team line-up declined, with the arrival of Jack Grealish for 100 million pounds, a record in the Premier League, and the emergence of Phil Foden, a graduate of the club's academy.
City had enhanced its attacking options for the new season by signing Norwegian Erling Haaland and Argentine Julian Alvares.