Balthazar got his start as a child actor in the film version of the classic novel Lord of the Flies (1990). Balthazar has modeled for Versace, Calvin Klein, and Tommy Hilfiger and has appeared in a range of small film roles and a handful of television parts, including Charmed, Traffic, and Alias. He is in the new film Feast and in the upcoming films West of Brooklyn and The Tripper with David Arquette and Courteney Cox. Balthazar is also a member of the band Ringside; their first album was released in 2005.