On her mother's side she is the half-sister of Charlotte Gainsbourg and Kate Barry, and of Lola Doillon and Lily on her father's side.

At the age of nine, her appearance was distinctive, with Indian leggings under short dresses, worn with Grateful Dead T-shirts and rollerblades, and long dreadlocks. By the time she was 11½, she had tattoos and a stud in her tongue.

She gave birth to her first child, a son Marlowe Jack Tiger Mitchell, in 2002. She parted company with his father, musician Thomas-John Mitchell, less than a year later and went to New York.

She started her acting career as her mother's daughter in Kung-Fu Master (1987). Then her father offered her her first great role in the movie Trop (Peu) d'Amour (1998), and she also played in Mauvaises Fréquentations (Bad Company) (1999). She became a model because of her atypical beauty and is now a known face in European cinema. She also starred in "House of Voices, aka Saint Ange." (1998)

As a model Doillon has appeared in the one-time Gap, Inc. publication "Individuals" and is the face and muse of the fashion house Givenchy. She also modeled for the 2007 Pirelli Calendar. In 2007 the heritage jeans brand Lee Cooper made her its creative partner but after a year of great reviews closed the line citing bankruptcy.

In 2006 Doillon began writing music with friend and musician Chris Brenner. A song they wrote together "The Girl Is Gone" was featured on the Visionaire Magazine special music issue and picture disk in 2007. Doillon sings, plays guitar and writes lyrics and is rumored to be writing material for an upcoming album with Brenner, musician John Mitchell and various artists.