Before starring on Lost (2004), Lilly worked a variety of other jobs. She apparently worked as a flight attendant, waitress, and completed oil changes on big rigs.To fund her university education, she modeled although she never considered herself a model. She appeared on G4's Judgment Day and in an uncredited role in the 2003 film Freddy vs. Jason as a high-school girl leaning against a locker, and some appearances in a few episodes of Smallville as an extra. She had a guest appearance on the ABC supernatural horror series Kingdom Hospital (2004). Lilly's first speaking role, however, was on Lost. She studied acting at The Yaletown Actors Lab with writer, director David Palffy and was first discovered by agent Jeff Palffy, formerly of Ford Models, now with PMG Management in Vancouver, who was instrumental in her first break on Lost.
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 grudgingly 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.
