After high school, Rachel Bilson enrolled at Grossmont College in San Diego, but after a year she left her studies to devote herself to her career in show business. Participate in some advertising, until in 2003 she made her debut as an actress in some episodes of series such as Buffy the Vampire Slayer (in the role of one of the Potential Slayers) and 8 Simple Rules. In the same year she got the role of Summer Roberts on The O.C. television series, which debuted in August 2003. Initially the character of Summer Roberts was to appear only in a few episodes, but given the success obtained thanks to the relationship with the character of Seth Cohen starring Adam Brody, Rachel Bilson is promoted as a regular member of the cast. The series gets a huge success and allows its protagonists to achieve international fame. Rachel starred in The O.C. until 2007, when the series is canceled, and it is one of the few cast members to have taken part in all 92 episodes that make up the series.
Parallel to the television success, Rachel Bilson also embarked on a film career. In fact in 2006 she made her film debut with a starring role in The Last Kiss. In the same year she received a role in Jumper, the film starring Hayden Christensen, coming out in theaters in 2008. In 2009, she is in the cast of the film New York, I Love You, a film which also stars Shia LaBeouf, Natalie Portman, Hayden Christensen and Blake Lively. In the same year she was among the protagonists of another romantic comedy titled Waiting For Forever.
In 2007 she returned to acting on television taking part in two episodes of the TV series Chuck, whose creator Josh Schwartz is the same creator of The O.C. In 2010 she made her debut in the fifth season of How I Met Your Mother series in the role of Cindy, the new love interest of the protagonist and roommate of the mysterious mother of the title; a recurring character who will continue to serve through the seasons. In 2011, she becomes the star of the new television series created by Josh Schwartz titled Hart of Dixie, in which she plays the role of Zoe Hart. In 2012, she appears in the last episode of the sixth season of Gossip Girl.