Breillat was born in Bressuire, Deux-Sèvres, but grew up in Niort. She decided to become a writer and director at the age of 12 after watching Ingmar Bergman's Gycklarnas afton, believing she had found her "'fictional body'" in Harriet Andersson's character, Anna. She started her career after studying acting at Yves Furet "Studio d'Entraînement de l'Acteur" in Paris together with her sister, actress Marie-Hélène Breillat (born 2 June 1947) in 1967. At the age of 17, she had her novel, l'Homme facile, (Easy Man) published. Ironically the French government banned it for readers under 18 years old.
Breillat is known for films focusing on sexuality, intimacy, gender conflict and sibling rivalry. Breillat has been the subject of controversy for her explicit depictions of sexuality and violence. She cast the pornstar Rocco Siffredi in her films Romance (Romance X, 1999) and Anatomie de l'enfer (Anatomy of Hell, 2004). Her novels have been best-sellers.
Her work has been associated with the New French Extremity tendency.
In an interview with Senses of Cinema, she described David Cronenberg as another filmmaker she considers to have a similar approach to sexuality in film.
Though Breillat spends most of her time behind the camera, she has been in a handful of movies, making her film debut in 1972 as Mouchette in Bernardo Bertolucci's Last Tango in Paris.
In 2004, Breillat suffered a stroke.
A friend of hers, Christophe Rocancourt, a con artist, was to play a role in the upcoming film "Bad Love". However, in 2009 she accused him of taking advantage of her handicap by embezzling €650,000. Breillat documented the incident in her book, published in 2009, called "Abus de faiblesse" (Abuse of Weakness).
As of 2010, Breillat is almost fully recovered from her stroke and still intends to film Bad Love with Naomi Campbell in a lead role. Departing from her native French, Breillat plans for the dialogue in the movie to be in both English and Chinese. In September 2010, Breillat's second fairy-tale based film, Sleeping Beauty (La belle endormie), will open in the Orizzonti sidebar in the 67th Venice Film Festival.