Barrell was born in Toronto, Ontario, Canada, to a Slovenian mother. She attended Assumption Catholic Secondary School in Burlington, Ontario, where she had a lead role in two school plays, in addition to collaborating with a friend on a play in which they wrote, directed and acted together. She directed her high school’s production of The Wizard of Oz and was a member of Burlington Student Theatre for two years. She started studying musical theatre at Sheridan College then transferred to George Brown College to study filmmaking and acting at the School of Media & Performing Arts, graduating in 2010. She also did some training at The Groundlings comedy school.
Barrell is an advocate for the “Pink Box Program” by GIRL TALK Empowerment, a Canadian organization that “inspires, empowers and mobilizes girls to become world-changers”.
She is married to actor Ray Galletti, whom she met on the set of My Ex-Ex. They became engaged in 2016 and married in 2017.
In July 2019, Barrell publicly took part in an article for Diva Magazine where she stated in an interview, “I am attracted to both men and women and the person I fell in love with is a man…I wish it could just be about the human I am in love with, not their gender.”
On September 8, 2021, Barrell gave birth to her son, Ronin Barrell Galletti.