Former Juventus and Italy striker Ravanelli, known as the White Feather in his playing days, took charge of the French side in the close season.
Ajaccio's fifth consecutive defeat in all competitions left the Corsica team second-bottom on seven points from 12 games.
"We have decided to part ways with Fabrizio Ravanelli and (assistant coach) Gianpiero Ventrone," Ajaccio's president Alain Orsoni was quoted as saying by French media.
The 44-year-old Ravanelli, who started as a coach with the Juventus Under-13 side two years ago, said his dismissal "hurt".
"That's football. I've worked, I've done everything I could to make it work. It did not. I'm not angry. We had a lot of problems, I never had the whole squad available," he told broadcaster Canal Plus.
- Sports & Recreation