Pellerin was born and raised in St. John's, Newfoundland and Labrador. After highschool she was selected to attend the prestigious National Theatre School of Canada in Montreal. Following her graduation she was cast in her first season at Soulpepper Theatre in Toronto. Her first professional play was Soulpepper's production of Tom Stoppard's The Real Thing, playing the role of Debbie opposite Megan Follows, Albert Schultz and C. David Johnson. In it she played the rebellious daughter to Albert Schultz's Henry. She has returned to Soulpepper every season since, playing a variety of leading and supporting characters in numerous productions.
Her first film was Killing Zelda Sparks, in which she starred opposite Mad Men's Vincent Kartheiser, and in her second film she appeared opposite Edward Furlong in Warriors of Terra. She made her television debut on the second season of The Tudors as Lady Elizabeth Darrell alongside Johnathan Rhys Meyers, where she spent 5 months filming in Dublin, Ireland. Her first featured role in television brought her home to St. John's, playing the role of Constable (later Sergeant) Leslie Bennett in CBC Television's Republic of Doyle.