STORY: "For Freedom," said Binoche as she snipped off a huge handful of her auburn hair and held it up to the camera.
Binoche was joined by other French A-list actresses and singers including Marion Cotillard and Isabelle Adjani in cutting their hair.
Pop stars Angele and Pomme also cut their locks in support.
The post has been widely relayed on other social media, including Facebook and Twitter.
"Iranian women expect support from the international community. This is a beautiful way to show that support," French lawyer Richard Sedillot, who initiated the action, told Reuters.
Lawyers, media personalities and other women in France have since followed suit.
Amini, 22, was arrested on September 13th in Tehran for "inappropriate attire" and died three days later in hospital, sparking waves of protest in which over 130 people have died, according to rights groups.