The London-based football club said on their website that Italian manager Sarri, 59, is Chelsea's new manager as he moved to Stamford Bridge after a three-year spell at Italian side Napoli.
On Friday, Chelsea parted ways with Italian manager Antonio Conte.
"I am very happy to be coming to Chelsea and the Premier League. It is an exciting new period in my career," said Sarri.
"I hope we can provide some entertaining football for our fans, and that we will be competing for trophies at the end of the season, which is what this club deserves," he added.
Sarri reportedly inked a three-year deal with Chelsea.
Under Sarri, Napoli twice finished the Italian league in second place. In addition Sarri bagged the Italian Serie A Coach of the Year award in 2017.
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