In addition to his film work, Schwartzman was the star of the HBO series Bored to Death (2009–2011), in which he played a writer who moonlights as an unlicensed private detective by advertising himself on Craigslist. He currently releases music through his solo project Coconut Records, and was formerly the drummer of rock band Phantom Planet.
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.
Schwartzman married long-time girlfriend Brady Cunningham at their home in the San Fernando Valley on July 11, 2009. Cunningham is an art and design director and co-owner of TENOVERSIX in Los Angeles. Schwartzman describes himself as "basically a vegan" as he does not eat meat, dairy, or eggs. He narrated a video, What to Eat: The Environmental Impacts of our Food, for Farm Sanctuary. He has two daughters, Marlowe Rivers Schwartzman (born December 4, 2010) and another born in May 2014.