The German replaced Frank Lampard as boss midway through the 2020/21 campaign and led Chelsea to Champions League glory, beating Manchester City in the final.
He followed that up with victory at the Club World Cup last season and was praised for his diplomacy while fielding difficult questions during the final days of Roman Abramovich's ownership last season following Russia's invasion of Ukraine.
This summer, new Chelsea owner Todd Boehly heavily backed Tuchel in the transfer market by investing more than £230m in the squad, with Raheem Sterling, Kalidou Koulibaly, Carney Chukwuemeka, Marc Cucurella, Wesley Fofana and Pierre-Emerick Aubameyang all arriving at Stamford Bridge.
But there was no immediate impact and Tuchel leaves with the club sixth in the Premier League table having lost three of their seven matches in all competitions this season.
“Chelsea have today parted company with Thomas Tuchel,” read a club statement.
“On behalf of everyone at Chelsea, the club would like to place on record their gratitude to Thomas and his staff for all their efforts during their time with the club. Thomas will rightly have a place in Chelsea’s history after winning the Champions League, the Super Cup and Club World Cup in his time here.
“As the new ownership group reaches 100 days since taking over the club, and as it continues its hard work to take the club forward, the new owners believe it is the right time to make this transition.
“Chelsea’s coaching staff will take charge of the team for training and the preparation of our upcoming matches as the club moves swiftly to appoint a new head coach.
“There will be no further comment until a new head coach appointment is made.”