Born to a Californian show-business family, Bilson made her television debut in 2003, and then landed the role of Summer Roberts on the prime-time drama series The O.C.

[9] Her British great-grandfather, George Bilson (1902–1981), who was born into an Ashkenazi Jewish immigrant family in Leeds, England, worked for RKO Pictures after emigrating to the United States,[3] heading the movie trailer department,[6] and her great-grandmother, Hattie Bilson (1907–2004), was a screenwriter[6] whose credits included Pal, Canine Detective (1950).

[9] She then made several appearances in commercials, including advertisements for Subway restaurants, Raisin Bran, and Pepto-Bismol.

[9] She made her TV acting debut in 2003, appearing in one episode of Buffy the Vampire Slayer and 8 Simple Rules for Dating My Teenage Daughter.

[19] In late 2006, Bilson was cast in Doug Liman's thriller Jumper, as the replacement for actress Teresa Palmer.

[22] In September 2008, she started shooting the indie romantic film Waiting for Forever, directed by James Keach.

In September 2009, Bilson appeared as a celebrity guest judge in the third episode of Project Runway (season 6).

In 2011, Bilson began starring in The CW series Hart of Dixie, executive produced by The O.C.

[28][29][30] The podcast focuses on the hosts and guests re-watching and discussing episodes of The O.C..[29] Several notable guests have appeared on the podcast such as Mischa Barton, Adam Brody, Peter Gallagher, Josh Schwartz, Jem, Bonnie Somerville and Elizabeth Gillies.

[33] On each episode, Bilson and Allen interview one or more people from the entertainment industry in a casual, conversational format.

[37] Bilson approached DKNY Jeans in late 2007 with a view to design a clothing line with the fashion brand.

[39] An advertising image was released in July 2008 which featured Bilson modelling her Edie Rose collection.

[42] Bilson's fashion and sense of style made her the unwitting target of the Bling Ring, who burglarized her home on several occasions.