[1] He joined the school choir to better express himself and was soon cast in the role of Rum Tum Tugger in the musical play Cats.

His first starring role on television was as John Doe in the 2008 CBC comedy series jPod, based on the novel of the same name by Douglas Coupland.

In 2010, Coombs appeared in a recurring role as Thomas Culpeper in the television series The Tudors, and in CBC's Heartland as Chase Powers.

On March 11, 2013, it was announced that Coombs had been cast in a lead role as Sebastian in the CW period drama series Reign.

[6] In early 2016, Coombs chose to depart from Reign as a series regular at the end of the third season, with the possibility to return as a guest star in future episodes.