Agnes Bruckner began her career at age 11. Agnes Bruckner appeared in commercials, a few television pilots, and on the daytime soap opera The Bold and the Beautiful in 1999. At the age of 15, Bruckner got her first lead role in the independent film Blue Car (2002), in which Agnes Bruckner played a high school student involved in an affair with her teacher, played by David Strathairn. Film critic Roger Ebert wrote that Bruckner "negotiates this difficult script with complete conviction." Bruckner received an Independent Spirit Award nomination for "Best Female Lead" for the role.
In the 2000s, other minor roles in television and film followed, including roles in The Glass House (2001), and the thriller Murder by Numbers (2002) starring Sandra Bullock. Bruckner has appeared in episodes of the television series 24 and Alias. Agnes Bruckner starred in the horror films Venom (2005) and The Woods (2006). Also in 2006, Agnes Bruckner appeared in the drama Peaceful Warrior, opposite Scott Mechlowicz and received a ShoWest Female Star of Tomorrow Award, and played the lead role in Dreamland.
In 2007, Bruckner appeared in the horror/romance film, Blood and Chocolate. Upcoming film roles include: Say Hello to Stan Talmadge (2008), Kill Theory (2008), Vacancy 2: The First Cut (2009) , and The Craigslist Killer (2011).