The Serie A champions on Sunday afternoon confirmed that Sarri has left Chelsea to take over the reins in Turin.
Sarri, who has singed a three-year deal with the Old Lady, leaves the Blues after just one season at Stamford Bridge. The 60-year-old joined Chelsea from Napoli in July 2018.
Chelsea won the Europa League title in Sarri's only season at the club, while the London outfit also secured Uefa Champions League football for next season with a third place finish in the English Premier League.
"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," said Chelsea director Marina Granovskaia.
"He also believed it important to be nearer his family, and for the well-being of his elderly parents he felt he needed to live closer to them at this point."
Sarri wants out of Chelsea
Sarri replaces Massimiliano Allegri in Turin.