

She played one of the main characters, Whitney, in the sequel to the horror film Hostel, Hostel: Part II, which opened in 2007. That year, she appeared in the teen horror-thriller Venom. She portrayed a leading role as Emily in the low-budget drama Havoc (2005), alongside Anne Hathaway. In 2004, Phillips starred opposite Jeff Bridges and Kim Basinger in The Door in the Floor, a film adaptation of John Irving's novel A Widow for One Year. Later, Phillips starred in the thriller feature Octane, which was released at the Cannes Film Festival in 2003 in the film, she appeared opposite Mischa Barton. In 2001, she appeared in the comedy Tart and in the drama Bully.

The film received four Academy Awards nominations and was a critical success but not a box office success. She appeared alongside Kate Hudson in the musical drama Almost Famous (2000). The film was directed by James Toback and starred Robert Downey Jr., Jared Leto, Brooke Shields and Elijah Wood, with whom she would later begin an off-screen romance. Phillips's performance was praised by film critics. Phillips made her film debut as Charlie in Black and White (1999). She used to party, drink and take drugs, explaining in 2002, "If you were 14 years old and able to live on your own in an apartment in New York City, and you got invited to all these clubs, and you got a bank account and you had a car service you could call so that you could go wherever you wanted. At 14, she quit school and moved into her own apartment with a housekeeper, just off Fifth Avenue. The youngest of John Phillips's children, she has one brother, Tamerlane, and three half-siblings: Mackenzie, Jeffrey, and Chynna. Named after the song "My Petite Bijou" by Lambert, Hendricks & Ross ( bijou means 'jewel' in French), Phillips was born in Greenwich, Fairfield County, Connecticut, and is the daughter of John Phillips of The Mamas & the Papas, and his then-wife, Geneviève Waïte, a South African model, artist, and actress.
