Born in Pont-Audemer, Cestac initially worked as an illustrator. In 1972, she took over the bookstore "Futuropolis" with her husband Étienne Robial, and transformed it into the comics publisher Futuropolis.
She created the humorous detective stories of Harry Mickson for the comics magazines L'Écho des savanes, Charlie Mensuel, Pilote and Ah ! Nana. After Futuropolis was bought by Gallimard in 1994, she created the series les Déblok for Le Journal de Mickey, working with Nathalie Roques.
Her series Cestac pour les grands, aimed at an adult audience, brought her popular success and recognition. One album, Le Démon de midi (1996), was adapted for the stage and as the 2005 film The Demon Stirs.
- 1989: Alph-Art humour, festival d'Angoulême, for Harry Mickson vol. 5
- 1997: Alph-Art humour for Le Démon de midi
- 2000: Grand Prix de la ville d'Angoulême
- 2014: Grand Prix Saint-Michel
- Jean-Pierre Mercier, Les Pieds de nez de Florence Cestac, Angoulême, Musée de la bande dessinée, 2001.
- La galerie des illustres, interview in Spirou no. 3665
- "French comics festival marred by sexism row - BBC News". BBC News. 6 January 2016. Retrieved 6 January 2016.