Chantal Sebire, 52, a former school teacher and mother of three, was suffering from an extremely rare form of cancer, which left her virtually blind, facially disfigured and in incredible pain.
A post mortem is to be carried out Thursday to establish the cause of death.
A Dijon court had earlier turned down Sebire's request to be given a lethal dose of barbiturates, ruling that it would contravene medical ethics and French law, which does not permit assisted suicide.
Her case revived the euthanasia debate in France after before-and-after pictures of her face were shown in the media. She also made a televised appeal last month, where she said that children ran away from her in fright due to her horrific appearance.
She said in her TV appeal for the right to die that, "One would not allow an animal to go through what I have endured."
Her lawyer said Serbire, who was diagnosed with the disease eight years ago, was unable to take morphine for the pain due to the side effects.
Sebire suffered from cancer of the nasal cavity known as an esthesioneurblastoma, which is so rare that in the past 20 years only 200 cases worldwide have been reported.
In Europe, euthanasia is only legal in the Netherlands and Belgium. Switzerland has a system which allows people to die in the country on the condition that the patients themselves apply the lethal dose.