She was born Shannon Mitchell on April 10, 1987 in Toronto, Canada to an Irish-Scott father, and a Filipino mother whose first cousin was Tony Award-winning performer, Lea Salonga. Interested in the arts at a young age, Mitchell began taking dance lessons at the age of five. When the future star was 10, her family moved out to Vancouver, British Columbia, where she attended an open casting call for an international modeling agency and landed the gig. Mitchell blossomed into a professional model by her late teens, strutting down the runways and gracing advertisements in Bangkok, Hong Kong and Barcelona. Yet with her early success in modeling, Mitchell was determined to fulfill her acting potential. She returned to Toronto to study acting and in 2009, made her television debut with a minor role in the long-running teen drama series, "Degrassi: The Next Generation" (The N, 2001- ). Following that performance, Mitchell landed her first recurring role on the action-packed series "Aaron Stone" (Disney XD, 2009- ). The show followed teenager Charlie Landers (Kelly Blatz) who assumes the role of his crime-fighting video game character in order to protect his family and the world.
In 2010, Mitchell was cast in a role that catapulted her career into teen superstardom. The actress starred in ABC Family's "Pretty Little Liars," a mystery drama series based on Sara Shepard's 2006 novel of the same name, about four friends whose lives begin to unravel following the mysterious disappearance of their clique's queen bee. Mitchell played Emily, the athletic and straight-laced member of the group, who realizes that she is gay. "Pretty Little Liars," which was described as a teen version of "Desperate Housewives" (ABC, 2004- ), struck a chord with viewers and critics for taking on real-world issues - from body image to homophobia - and giving young women hope and courage to confront their own problems. "Liars" also turned Mitchell and her co-stars Troian Bellisario, Ashley Benson and Lucy Hale into Hollywood "It" girls, gracing the covers of magazines and attending major events. Mitchell also earned praise from organizations such as The Gay and Lesbian Alliance Against Defamation (GLAAD) for her positive and accurate representation of a gay teen on television.