In 2006, Therriault portrayed Tommy Douglas in the CBC Television special Prairie Giant: The Tommy Douglas Story. He was subsequently nominated for a Gemini Award for Best Performance by an Actor in a Leading Role in a Dramatic Program or Mini-Series. The show received a total of nine nominations, including Best Writing in a Dramatic Program or Mini-Series and Best Dramatic Mini-Series.
On Monday, October 20, 2008, Therriault took part in a tribute to the late Richard Monette, former artistic Director of the Stratford Shakespeare Festival.
On April 27, 2009, it was announced that Therriault will appear as Irving Berlin, alongside Michael Boatman as Scott Joplin, in The Tin Pan Alley Rag, which centers around the imagined meeting of the two great Musicians. The Tin Pan Alley Rag is presented by Roundabout Theatre Company in New York, June 12 to September 6, 2009.
