Tuchel joined in January with the Blues languishing in ninth in the Premier League.
But Chelsea were revitalised by Tuchel’s arrival, climbing the table to finish fourth before winning European club football’s biggest prize against Manchester City in Porto last weekend.
“I cannot imagine a better occasion for a contract renewal. I am grateful for the experience and very happy to stay part of the Chelsea family,” said Tuchel.
Tuchel was unceremoniously sacked by Paris Saint-Germain in December despite winning two Ligue 1 titles in his first two seasons in charge and leading the French giants to their first ever Champions League final in 2020.
The 47-year-old was handed just an 18-month deal when he arrived in London, but his success in guiding Chelsea to a second European Cup triggered a clause in his initial contract for an extension.
“Chelsea Football Club is very happy to confirm that, following our triumph in the Champions League, Thomas Tuchel’s contract has been extended by two years, as agreed when he joined the Club,” the club said in a statement.