The Italy international has penned a five-year deal with the Blues, becoming Maurizio Sarri's first signing for the club
Chelsea have completed a deal to take Napoli's Jorginho to Stamford Bridge, the club have announced.
Earlier on Saturday, the Blues confirmed that they had lured Maurizio Sarri to lead the club for the next three years following the sacking of Antonio Conte on Friday, and his first move has been to secure the signing of the midfielder on a five-year deal.
The Blues will pay £57m (€65m/$86m) for the player.
He played 33 times for Napoli in Serie last season, scoring two goals and creating four more from his deep-lying position in the midfield as they finished second behind Juventus in the standings.