Sarri returns to Italy on a three-year deal just a season after leaving Napoli for Stamford Bridge, where he failed to garner fan support despite winning the Europa League and returning the Blues to the Champions League thanks to a third-placed finish in the Premier League.
"Maurizio Sarri has returned to Italy, where he has coached for the majority of his career. And from today, he will take over the reins at Juventus with a contract until June 30, 2022," Juventus said in a statement.
The Europa League win last month was Sarri's first major trophy as a coach, but he will be expected to deliver far more in Turin.
Juventus have won Serie A for the past eight seasons, denying Sarri's former club Napoli in the process.
However, Massimiliano Allegri left at the end of the campaign after failing to guide the Italian giants to Champions League glory despite the signing of Cristiano Ronaldo last year.
With Ronaldo now 34, winning the Italian giants' first Champions League title since 1996 will be Sarri's top priority.
Chelsea, meanwhile, must now turn their attentions to hiring an 11th permanent manager of Roman Abramovich's reign in charge of the club.
"In talks we had following the Europa League final, Maurizio made it clear how strongly he desired to return to his native country, explaining that his reasons for wanting to return to work in Italy were significant," Chelsea director Marina Granovskaia said in a statement.
Chelsea are expected to try and lure the club's record goalscorer Frank Lampard back to Stamford Bridge.
Lampard has had just one full season in club management at Derby County, who he led to the final of the Championship playoffs.