Videos on social media showed film stars, mostly from France, chopping off locks of their hair as part of a protest movement that has spread around the world.
Thousands of videos and statements have been posted under the hashtag #HairForFreedom.
Nationwide protests have rocked Iran in recent weeks after the death of Amin, 22, while in the custody of the country's morality police.
She was detained for allegedly breaching strict rules on clothing.
Well-known names in French cinema including Juliette Binoche, Marion Cotillard, Isabelle Adjani and Isabelle Huppert, as well as the Belgian singer Angele, have cut their hair to show support for the protests.
Binoche, who won an Academy Award for her role in 1996 film The English Patient, said "for freedom" as she used scissors to take off a handful of hair, before brandishing it in front of the camera.
She was joined by at least 50 French celebrities who expressed anger over the way women are treated in Iran.
Videos of women including Cotillard and Binoche were released on Instagram account “soutienfemmesiran”, which translates as “support women in Iran”.
Julie Gayet, wife of former French president Francois Hollande, also filmed herself cutting her hair.
A Swedish member of the European Parliament, Abir Al Sahlani, cut off her ponytail during a speech.
Ms Al Sahlani, who is of Iraqi origin, was at the time addressing the EU assembly in Strasbourg about the oppression of women in Iran.
"Until Iran is free, our fury will be bigger than the oppressors. Until the women of Iran are free, we are going to stand with you," she said.
She quoted the Kurdish slogan "Jin, Jiyan, Azadi", which means "Woman, Life, Freedom", as she held up her ponytail.
Iranian-born Hollywood actress and activist Nazanin Boniadi has also joined the protest movement.
She said more must done to protect the rights of women in Iran.
"I think the death or the killing of Mahsa Amini in custody in Iran has struck at the core of everything we feel about our rights being taken away from us, how fragile our freedoms can be," she told Reuters.
"So it's hit a chord ... in the global zeitgeist of people feeling like they can relate to what it feels like to have your rights taken away from you. And particularly, I think, women's rights."
Cutting off hair is a traditional method of protest for women in Iran.
In The Shahnameh (Book of Kings), an epic poem written by the Persian poet Ferdowsi between 977 and 1010, refers to a princess cutting her hair to protest over the death of her husband.