Early life

Lilly served briefly as a foreign missionary and lived in a grass hut in the Philippines. She founded and ran a world development and human rights committee while studying international relations at the University of British Columbia. She has been a volunteer for children's projects since she was 14. Lilly is a former flight attendant and is fluent in French.

Lilly was discovered on the streets of Kelowna, British Columbia by Ford modeling agency. Although she initially decided to pass on a modeling career, she went ahead and signed with Ford anyway, to help pay for her University of British Columbia tuition and expenses. Despite being signed to Ford Models, she was never actually a fashion model. - "People don’t realise Ford has an acting branch,” she said. “So I was never really a model.”

She was previously featured in several LiveLinks Chatline television commercials, which were shown on The Late Show with David Letterman when she was a guest, and on G4's Judgment Day. She appeared (uncredited) in the 2003 film Freddy vs. Jason as a high-school girl leaning against a locker and in an episode of Smallville. She also had a guest appearance on the ABC supernatural horror series Kingdom Hospital (2004).

When Lilly was cast as Kate in Lost, her main concern was acquiring a work visa to enter the United States. With production literally days away and no news about the visa, casting directors were forced to begrudingly begin re-casting the role of Kate. After nearly 20 auditions, Lilly's work visa was approved/cleared but she arrived on set a day late. Her salary in 2004 for Lost was $80,000. On the heels of her role in Lost, she was voted one of the Breakout Stars of 2004 by Entertainment Weekly. Although Lilly placed eighth in the FHM 100 Sexiest Women in the World 2006 and initially placed second on Maxim's Hot 100 list of 2005, she slipped to #67 in Maxim's 2006 list.