Tuchel, who arrived in January 2021 on the London bench, had won the C1 four months later with Chelsea, current 6th in the Premier League and which changed ownership in May with the arrival of a consortium of investors led by the American businessman Todd Boehly.
The name of his successor is not yet known.
"Thomas will keep a deserved place in Chelsea history having won the Champions League, European Super Cup and Club World Cup during his tenure," the club wrote in a statement.
"But, as the new management celebrates 100 days at the helm of the club, and continues to work hard to move the club forward, the new owners believe the time is right to make this change," it read.
Tuchel, 49, is sacked after a very mixed start to the season for the Blues, who have nevertheless spent lavishly on the transfer market with some 300 million euros invested in the transfer window for players like Raheem Sterling, Wesley Fofana or Pierre-Emerick Aubameyang.
But the sauce was slow to take and the inaugural defeat in Zagreb, Tuesday for the 1st day of the Champions League, was fatal to the German technician, already weighed down by two defeats in six days of the Premier League.
Chelsea, who face Fulham on Saturday in the Championship, will have to quickly pull themselves together with a crucial match against Salzburg next Wednesday in C1.
"The management will take charge of training the team and preparing for our upcoming matches as the club intends to appoint a new coach quickly," said Chelsea, without specifying a timetable.
© 2022 AFP