The 57-year-old was fired after the Istanbul team’s 2-0 defeat to Anderlecht during a European Champions League match on Wednesday, Ansa reported.
The result meant the team finished bottom of Group D and will exit the competition despite having one game left to play.
He is expected to be replaced by Fatih Terim, the current assistant coach, Ansa said.
Prandelli quit as Italy coach after the team’s exit from the World Cup in the group stage and was appointed by the Turkish side in early July.
Before taking the Italy post in 2010, Prandelli had led a 20-year career coaching squads including Fiorentina and Parma. During his career on the pitch he played for Juventus and a number of other Italian teams.