Rachel Bilson was born in Los Angeles, California.
Her mother, Janice (Stango), is a sex therapist, and her father, Danny Bilson, is a writer, director, and producer. Her father is Ashkenazi Jewish and her mother is of Italian descent.
Bilson attended Grossmont College, a community college in a suburb of San Diego, but dropped out after one year, taking her father's advice to pursue a professional acting career. She then made several appearances in commercials, including advertisements for Subway restaurants, Raisin Bran and Pepto-Bismol. She made her screen acting debut in early 2003, appearing in one episode of Buffy the Vampire Slayer and 8 Simple Rules for Dating My Teenage Daughter. Bilson was subsequently cast in The O.C., which debuted in August 2003. Her character, Summer Roberts, was initially intended to appear in only a few episodes, but became a series regular after a successful run, as Bilson's on-screen romance with Seth Cohen (Adam Brody) became a noted aspect of the series.
As a result of the success of The O.C., Bilson has become well known among teenage audiences. At the 2005 Teen Choice Awards, Bilson collected three awards: "Choice Hottie Female", "Choice TV Actress (Drama)" and "Best Onscreen TV Chemistry" (jointly won with Adam Brody). In 2005, Maxim magazine named her sixth in their annual "Hot 100 List"; in 2006, the publication awarded her #14. The UK edition of FHM Magazine named her 28th in the 2006 100 Sexiest Women in the World list, while the US Edition Ranked her 77th in 2005. Bilson was also named one of People magazine's "100 Most Beautiful People" in 2006.
Bilson's first film role was in The Last Kiss, a romantic comedy-drama also starring Zach Braff. In the film, which opened in 2006, she plays a college student who seduces Braff's character. It was reported that she called for a body double during the sex scenes because she was uncomfortable being nude in front of the camera. She does appear in the scene for the final film, wearing a flesh-colored bra. "I was terrified!" she admitted. "But Zach really helped me through it, and we're friends, so he made it very comfortable, and Tony made it very comfortable, and it was actually a really nice setting. And I'm happy I did it, because I can say I did my first sex scene, and I never have to do that again!" One review of the film noted that Bilson played the role with "surprising depth", although another critic described her role as "Glenn Close in Fatal Attraction as an airhead valley girlwith a hot bod".
Bilson has stated that she prefers acting in feature films to appearing on television, and that she would like the kind of roles "that Natalie Portman and Scarlett Johansson are offered". She has specified that though she is "grateful" for the success of The O.C., she feels that the show "is over" and that she is "ready to move on" to film roles. In September 2006, Bilson refuted rumors she had been cast to star in a film version of the comic book character Wonder Woman.
In late 2006, Bilson was cast in the role of Millie in Doug Liman's thriller Jumper, as the replacement for actress Teresa Palmer; the film was released on February 14, 2008. She also appeared in a two-episode arc on The O.C. creator Josh Schwartz's NBC comedy, Chuck, and in the film New York, I Love You, and appeared in the 100th episode ofHow I Met Your Mother ("Girls Versus Suits") as Ted Mosby's latest love interest. In September 2008, she started shooting the indie romantic film Waiting For Forever, directed by James Keach. In September 2009 Rachel appeared as a celebrity guest judge in the third episode of Project Runway (season 6). She starred in the 2011 indie film L!fe Happens next to Krysten Ritter and Kate Bosworth.