Stroppa, a former AC Milan midfielder and Italy international, took charge of Venezia in June last year and helped them earn promotion back to Italy's top flight after a one-season absence with a first-placed finish in Serie B.
"The club would like to thank Giovanni Stroppa and his staff for their work, professionalism, dedication and commitment throughout their time with the arancioneroverde," Venezia said in a statement.
Paolo Zanetti and Davide Nicola are among the candidates being considered as replacements for Stroppa, Italian media reports said.