Michael Bruce Patrick Seater was born in Toronto, Ontario. Michael began acting in the late 1990s and appeared in the short films Night of the Living and The Stone Skipper, and had minor roles in the direct-to-video film Future Fear and the made-for-television films Rescuers: Stories of Courage: Two Couples, Vanished Without a Trace, On Thin Ice, Dirty Pictures, Cyber Seduction: His Secret Life, the Hanukkah-themed Jenny and the Queen of Light, as well as in episodes of several television series, including The Zack Files.
Seater voiced the title character in the series Mattimeo: A Tale of Redwall, which aired in 2000, starred as Lucas Randall in the television series Strange Days at Blake Holsey High, which began airing in 2002 and ended in 2006, and had a role in the 2005 film The Prize Winner of Defiance, Ohio, which starred Julianne Moore.
Seater appeared in the recurring role of Owen on the series ReGenesis, which ended after its fourth season, and played Derek Venturi on another Canadian series, Life with Derek, which began in 2005 and ended in 2009 after four seasons. Seater had written a script for an episode of the show's fourth season with his brother, Graham. In 2009 he played a character in the Degrassi movie Degrassi Goes Hollywood.
He played the recurring role of murderer and criminal mastermind James Gillies in Murdoch Mysteries, seen in 5 episodes and mentioned in 3. No matter how many times he asks, nobody will tell him if Gillies is really dead.