Lilly was born in Fort Saskatchewan, Alberta, Canada to a devoutly Christian family. Her father is a home economics teacher, and her mother is a beauty consultant. Lilly also has a younger sister, whom she has described as "the actor in the family." During her childhood, the family did not have a television.

Before leaving the city of Fort Saskatchewan at the age of 10, she attended three elementary schools. She briefly attended Fort Elementary, Rudolph Henning and James Mowat Elementary. During a phone interview with the local paper, The Record, Evangeline was quoted saying, "When I was a kid, the Fort was tiny. I could ride my bike at five years old from one end of town to the other ... To me Fort Saskatchewan holds a lot of really great memories. I just consider it a little happy hideaway." She also recalled a favorite memory saying, "I remember that there was a drunk driver who was wheeling through town. I remember literally the men sending the women and children into the homes. Then they gathered themselves and ran after this truck. They actually jumped into the cab and jumped onto the window and forced the guy to pull over and go to the cop shop."

Lilly served briefly as a foreign missionary and lived in a grass hut in the Philippines at the age of 18. She was offered a missionary post there for two years, an offer she nearly accepted but eventually declined because of her parents' wishes. 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 of Air Canada, and speaks French fairly well.

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, working instead with their acting branch.

She was previously featured in several LiveLinks Chatline television commercials 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 in a pool hall scene. She also had a guest appearance on the ABC supernatural horror series Kingdom Hospital (2004). Lilly's first speaking role was on Lost. She also appeared in the 2003 teenager film The Lizzie McGuire Movie as an (uncredited) Italian police officer.

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.

Her salary in 2004 for Lost was $80,000 per episode. On the heels of her role in Lost, she was voted one of the Breakout Stars of 2004 by Entertainment Weekly. Although Lilly placed 8th in the FHM "100 Sexiest Women in the World" of 2006 and initially placed 2nd on Maxim's "Hot 100" list of 2005, she slipped to 67th in Maxim's 2006 list. On December 14, 2006, Lilly was nominated for a Golden Globe for Best Lead Actress-Drama. Action figures of Lilly's Lost character were released during the holiday season of 2006.

Lilly was once married to Canadian hockey player Murray Hone, but is believed to be engaged to her former Lost co-star Dominic Monaghan. Her known nicknames include "Evie" and "Monkey". Her Lost castmates nicknamed her "Monkey" because of her ability to climb trees with ease, a skill which has been incorporated into her character. Her fellow Lost-actor Josh Holloway also calls her 'Freckles', sharing the nickname his on-screen character Sawyer gave her. She is also known on set for her tomboyishness, Christian faith, and her "potty mouth."

Lilly has stated that she "live[s] in a bubble," specifying that she is not familiar with popular culture and does not watch television or own a TV set. She has also said that she would not appear in a nude scene or perform in sexual scenes that she would consider "gratuitous".

On the May 9, 2007 Episode of Jimmy Kimmel Live, Evangeline Lilly described her deep need to leave her home town after her high school graduation. She did much travelling at this point in her life, moving from town to town approximately every six months. She stated that in each town she took on a persona, for example, she would decide in one town to take on the role of a "nerdy bookworm" and in another she decided to be a ditzy "cheerleader" type and acting as such she would frequently date different men.

Lilly has also used her celebrity status to help promote Just Yell Fire, a video aimed at teaching teenage girls how to defend themselves against rapists. During the summer break between the first and second seasons of Lost, Lilly spent time visiting the poor in Rwanda.

On December 20, 2006, Lilly's house in Kailua, Hawaii was completely destroyed by fire while she was on the Lost set with one of her two roommates, both of whom work as her stand-ins on the show. The second roommate was off-island at the time of the blaze, which occurred on the final day of shooting before the show’s holiday break. The cause of the fire has now been determined as an electrical fault.

• Founded and ran a world development and human rights committee at her university. She has lived under a grass hut in the jungles of the Philippines with a missionary group, and has been a volunteer for children's projects since the age of 14.
• Fluent in French and loves ice skating, canoeing, kayaking, snowboarding and rock climbing.
• Refused to do a partial nude scene in an early episode of "Lost" (2004).
• Voted one of the Breakout Stars of 2004 by Entertainment Weekly Magazine
• Named #2 on the Maxim magazine Hot 100 of 2005 list.
• Prior to her starring role on "Lost" (2004), she worked as an extra on film sets to help pay her University tuition. She can be seen in episodes of "Tru Calling" (2003), "Dead Like Me" (2003) and "Smallville" (2001), and in several films including White Chicks (2004), Stealing Sinatra (2003) and Freddy vs. Jason (2003).
• Presented The Tragically Hip at Live 8 Canada.
• Has two sisters - younger sister is named Andrea.
• Before starring on "Lost" (2004), she worked a variety of other jobs. She has worked as a flight attendant, waitress, and completed oil changes on big rigs while doing commercials and modeling to earn money for University.
• Her father is a Home Economics teacher in Canada. Her mother worked as a cosmetician and ran a daycare center.
• Attended the University of British Columbia where she attained a degree in international relations.
• Kate, her character on "Lost" (2004), is frequently seen climbing trees. This is because the very athletic Lilly loves to climb trees herself.
• First discovered by agent Jeff Palffy, formerly Ford Models, now with PMG Management in Vancouver, who was instrumental in her first break on Lost.
• Ranked as #75 in FHM's "100 Sexiest Women in the World 2005" special supplement. (2005)
• In 2003, she was cast in several commercials for a dating hot-line called "LiveLinks". The late-night ads ran for over two years on basic cable channels, even after she made it big on ABC's hit drama "Lost" (2004). During a guest spot on "Late Show with David Letterman" (1993), David Letterman embarrassed the actress by playing one of her commercials on the show.
• Named #73 in FHM magazine's "100 Sexiest Women in the World 2006" supplement. (2006).
• Her house in Hawaii was destroyed by a fire. Luckily, no one was hurt. [December 2006]
• Ranked #68 on the Maxim magazine Hot 100 of 2007 list.

"I'm very picky when it comes to men. I come across a man who I'm really attracted to about once every five years" "I love being outside - that's where I'm the happiest."