Sarri has long been keen on a move to Stamford Bridge and has been in dialogue to secure his release from his Napoli contract in a gentleman's agreement, with Carlo Ancelotti having already been announced as his replacement.
Chelsea have explored, and spoken to, several other options but have decided that Sarri is their best choice, with Laurent Blanc among a group of managers to have been contacted over the upcoming vacancy.
Antonio Conte is still officially Chelsea's head coach and there is likely to be an agreement over his exit package, with the Italian having strained relationships with both club director Marina Granovskaia and up to seven first-team players.
The cost of Conte's exit, which could cost £9 million, and the fee for Sarri are not yet fully agreed but the contract for Chelsea’s main target is expected to be a three-year deal and an agreement on terms is likely to be a formality.
Chelsea are beginning to work in the transfer market again after making progress on their managerial situation, with several targets outlined by Sarri. The majority of Sarri's preferred targets come from Serie A and include Gonzalo Higuain, Dries Mertens and Kalidou Koulibaly, who have all played under the 59-year-old.
However, Chelsea's board will remain in control of transfer policy and their rule of only offering players over the age of 30 one-year deals, except in exceptional circumstances, will likely remain in place.
The appointment of Sarri will please Eden Hazard, who is still to sign a new Chelsea deal. The Belgian playmaker has two years left on his current contract and the club are keen to secure a renewal, with Hazard hoping the Blues will move to a more attractive style of play next season.
Meanwhile, Chelsea have conducted their first piece of minor transfer business of the summer transfer window, having loaned out highly-rated youngster Trevoh Chalobah to Ipswich Town.