McCormack began her career on stage. Since the early 2010s, she has played a variety of supporting roles in a number of productions, including in the television series Defiance, 11.22.63, and Damien, as well as in the web series Teenagers and That's My DJ.

In 2013, she wrote her first feature film, Play the Film, in which she also starred. The film was produced for only $1,000 CAD. For her work on the film, McCormack won various awards, including Best Screenplay at the Broad Humor Film Festival. The following year, she wrote a second feature film, Barn Wedding, which screened at film festivals throughout 2015.

In 2017, McCormack served as a Producer and Actress on several productions. In February of that year, she joined the cast of the Syfy science fiction television series Killjoys in its third season. On the series, she portrays Zeph, an androgynous scientist. That summer, the CBC mockumentary, The Neddeaus of Duquesne Island, which McCormack both produced and starred in, was released online via CBC's official website. In November 2017, she joined the cast for the third season of the CraveTV series Letterkenny. Also in 2017, McCormack developed and performed in Charlotte: A Tri-Coloured Play With Music, an original opera based on the life of German Painter Charlotte Salomon, which ran at the 2017 Luminato Festival in Toronto and at the World Stage Design Festival in Taipei.

In early 2018, she appeared in an episode of the CBC comedy series Crawford. Her third feature film as a Screenwriter, Sugar Daddy, will be directed by Wendy Morgan, and is slated to be filmed in late 2018.