The vastly experienced 67-year-old tactician was only appointed in July and has paid the price for a disappointing start to his tenure.
Zeman was charged with the task of improving on Cagliari's 15th-placed finish in Serie A last season by new owner Tommaso Giulini.
The former Roma coach has only masterminded two victories from the first 16 league games and Cagliari are without a win in their last eight league games.
Cagliari sit third-bottom of the table and it was announced on Tuesday that Zeman has been relieved of his duties.
A statement on the club's official website said: "Cagliari Calcio announces that Zdenek Zeman leaves the technical guidance of the first team.
"The company would like to thank the coach and all his staff for the work done in recent months with great professionalism and dedication."
