The 59-year-old has succeeded fellow Italian Antonio Conte, who was sacked by the club.
In his first news conference as Blues head coach, Sarri suggested the difference in styles would mean a period of adjustment for the players.
“Antonio has reached incredible results here and elsewhere,” Sarri said, speaking through a translator. “He is an extraordinary manager. I play in a slightly different way so it will take some time.
“All good things Antonio Conte did should be left and must not be changed.”
Sarri has a reputation for playing an attacking brand of football with a high intensity – a system widely admired during his time at Napoli.
He added: “It will take some time to build a different way of playing.
“It is important to know how to impose one’s football philosophy in such a short time.”
This post was last modified on 18/07/2018