Clark is best known for his role as Sean Cameron on the Canadian CTV series Degrassi: The Next Generation and as Steve Rendazo in the 2007 film Juno.
He has two younger brothers Robert Clark, who starred in The Zack Files and Strange Days at Blake Holsey High, and Aaron Brown.
He made a number of appearances on TV series, including Eerie Indiana: The Other Dimension, Goosebumps and Are You Afraid of the Dark?, and featured roles in films such as Grizzly Falls and Fizzy Bizness.
[3] From 1999 to 2000, Clark portrayed Tim "The Friend" Thomkins on the children's television show I Was a Sixth Grade Alien!, alongside future Degrassi co-star Ryan Cooley.
[11] In 2014, Clark moved from New York and back to Toronto to join brother Robert in building a new business, RDC Management and Holdings.