The decision was announced on Tuesday, with Venezia having lost their opening six league matches as they struggle to adapt to life back in Italy's top flight.
Stroppa took charge in June last year and guided Venezia to promotion from Serie B after they finished top of the second division. However, he has been unable to carry that success into the new season.
The former AC Milan midfielder and Italy international leaves after failing to find a solution to Venezia's poor form.
In a statement, the club thanked Stroppa and his coaching staff for their efforts.
"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.
Italian media reports have named Paolo Zanetti and Davide Nicola as possible candidates to replace Stroppa, although the club has yet to announce a successor.
Venezia now face a difficult challenge as they look to turn their season around, with eighth-placed Napoli due to visit on Saturday.
Manuel Akanji has admitted he is unsure what will happen to Manchester City's trophies following the club's guilty verdict over financial rule breaches, but the Inter Milan defender hopes he will get to keep his titles.
Atalanta ended their three-match losing streak in Serie A with a 3-1 victory over Venezia, who remain without a point after six matches.
Lazio moved level on points with Serie A leaders Inter Milan after beating Monza 3-1, while AC Milan were held to a 1-1 draw by Sassuolo.
Scott McTominay has been cleared to return to competitive football after recovering from a heart procedure, with Napoli confirming the midfielder is fit to play again.
