Wilde was born in New York City on March 10, 1984. Her mother, Leslie Cockburn (née Redlich), is a 60 Minutes producer and journalist, and her London-born father, Andrew Cockburn, is an Irish journalist, as are her paternal uncles Alexander Cockburn and Patrick Cockburn, all of whom are contributors to the political website CounterPunch.org. Her sister, Chloe Cockburn, is a civil rights attorney in New York. Her aunt was the late writer Sarah Caudwell and her paternal grandfather was the novelist/journalist Claud Cockburn. Through her grandfather, she is also a distant relative of English novelist Evelyn Waugh. Wilde has said that as a result of her family background, she has a "strong journalistic streak", being "really critical and analytical". Both her parents were prominent in the Washington social scene, hosting dinner parties. Her mother once recounted a story of a young Wilde eavesdropping one night on a conversation between Richard Holbrooke and Mick Jagger until Jagger noticed her and shooed Olivia to bed. She has wanted to become an actress since the age of two. For a short time, Wilde's family had a house in Guilford, Vermont. She attended Georgetown Day School in Washington, D.C., as well as Phillips Academy in Andover, Massachusetts, graduating in 2002. She also attended The Gaiety School of Acting in Dublin, Ireland for a short time. She initially began working as a casting assistant.
Wilde has appeared in the films The Girl Next Door, Alpha Dog, Conversations with Other Women and Turistas. She became known for her role on The O.C. as Alex Kelly, although she originally auditioned for the role of Marissa Cooper. She has also appeared in the Dashboard Confessional music video for "Stolen", and the French Kicks music video for "So Far We Are". She was strongly considered to play Bond girl Vesper Lynd in the 21st Bond film Casino Royale but Eva Green eventually won the role.
In 2009 Wilde was ranked #1 on Maxim magazine's Hot 100. It was an honor which was included as an inside joke during the House episode "The Tyrant", where House, upon hearing about Foreman's recent firing of Wilde's character, sarcastically teased, "My condolences. Although, it's not like she's the hottest woman in the world." She was also ranked #95 on the FHM 100 Sexiest Women of 2006. She was one of the key models in Abercrombie & Fitch's "Rising Stars" campaign in summer of 2004.
In 2007, Wilde was a part of the ensemble cast of the short-lived NBC mid-season drama The Black Donnellys. Her character, Jenny Reilly, was the lone principal female character in the series following the lives of an Irish-American family tied to organized crime in New York City. Also in 2007, Wilde appeared in the play Beauty on the Vine, a political thriller, playing three different characters.
Wilde joined the cast of the Fox medical drama House in autumn 2007, playing a young internist, Dr. Remy Hadley, nicknamed Thirteen, who works closely with Dr. House. Wilde told Star magazine how she sometimes takes cues from her character even when she's not working, saying, "I'm now convinced that I'm a doctor. I mean, if someone says they have a pain, I'm like, 'Well, that's your spleen.'"
The New York Observer has described Wilde as having a "throaty voice" and the "wide, teal-eyed charisma of Hollywood in the days of yore". She has cited Meryl Streep, Sigourney Weaver, Frances McDormand, Catherine Keener and Robin Wright Penn as acting inspirations.
She won the 2006 US Comedy Arts Festival Film Discovery Jury Award for Best Actress for Bickford Shmeckler's Cool Ideas (2006) and in 2008 at the Teen Choice Awards she was nominated for the Teen Choice Award for Choice TV Breakout Star Female for House M.D. and won the Rising Star Award at the Vail Film Festival.
On October 7, 2008, Wilde appeared in a video on funnyordie.com showing how much she enjoys registering early for the 2008 Presidential election, "Olivia Wilde Does It Early". Wilde appeared alongside Jack Black and Michael Cera in the 2009 comedy Year One.
She features as Quorra in Disney's Tron: Legacy, which opened on December 17, 2010.