The managerial shift comes just three days after the club lifted the DFB-Pokal trophy – their first major piece of silverware in five years.
Tuchel, who also guided the club to third in the Bundesliga , was rumoured to have had various bust-ups with senior figures within the club.
Dortmund have now sacked the German, who replaced Jurgen Klopp in 2015, with one year remaining on his contract.
The man himself has taken to Twitter, writing: “I am grateful for two beautiful, eventful and exciting years. Too bad that it does not go [on]. Thanks to the fans, to the team, to the staff and to all who supported us. Wishes the @BVB all the best. TT.”