Conte, 48, had returned to full pre-season training at the start of the week despite huge uncertainty surrounding his future at the club, but with one year left on his contract the Blues have chose to relieve the Italian tactician from his duties in west London.
The sacking brings to an end a fractious two-year relationship between Chelsea and Conte.
Antonio had reported for three days of pre-season training with the senior side this week, due to complications between Napoli and the West London club in reaching an agreement over compensation for Sarri.
But it will be another fresh start for Chelsea with Sarri becoming the club's seventh permanent manager since 2011.
"We won our sixth league title and eighth FA Cup".
The chain smoking former Empoli manager - who will have to restrain himself on the touchline in England where smoking is banned - was named Serie A Coach of the Year in 2016-17.More news: Twitter purge means fewer followers for Trump, Obama, Justin Bieber
Conte's average of 2.14 points per game in the Premier League is bettered only by Alex Ferguson (2.16) and Guardiola (2.34).
Alvaro Morata flopped at Chelsea last season following his move to the club from Real Madrid. And the club now has less than a month for their new manager to make an impact before their Premier League opener away at Huddersfield on 11 August.
Many will argue the move is a harsh one, as Conte was decent throughout his reign and he can leave with his head held high as the Blues did not have a trophy-less season during the two terms under his tutelage.
Trophies: Premier League 2016/2017, FA Cup 2018.
Sarri's appointment at Stamford Bridge is imminent now and it's believed that the Italian has begun building his backroom staff ahead of his first season in English football.
The question after Antonio Conte's departure from Chelsea on Friday was not 'where did it all go wrong?' but rather 'why did it take so long?'.