Youth coach Daniele Galloppa will take over on an interim basis, but the search for a permanent successor will start promptly as the club seek to avoid a relegation battle.
"ACF Fiorentina can confirm that Stefano Pioli has been relieved of his duties as head coach of the first team," a club statement said. "The club would like to thank him and his staff for the professionalism shown during their time at Fiorentina."
"Daniele Galloppa will take charge of the first team temporarily, starting from this afternoon's training session."
Winner of a Serie A championship in 2021/22 with AC Milan, Pioli has experienced a significant drop in performance and results in recent years.
In 2024, he was hired by the Saudi club Al-Nassr, where Cristiano Ronaldo played, but enjoyed little success in Saudi Arabia.
Now, his time in Florence will be looked back as even worse.