Schwartzman's acting career began when he was 17 years old, when he starred in Wes Anderson's Rushmore in 1998. Prior to Rushmore, he had no acting experience. Shortly after in 2000, Jason had a guest role in the short-lived series Freaks and Geeks. In 2001, he starred in CQ, a film by his cousin Roman Coppola. In 2002, he starred in Slackers and in 2003 starred in Spun. In 2004, he starred in I Heart Huckabees, and Shopgirl in 2005. He also appeared in various television shows, such as Cracking Up. In 2006, he starred in Marie Antoinette under the direction of his cousin, Sofia Coppola, in which he appeared as King Louis XVI.