Harris Allan began his professional acting career in Vancouver, Canada at the age of 12, as a guest star on the television series, The New Addams Family. At 15 he guest-starred on the series, Cold Squad. He has also appeared in the WB series, Smallville, and the USA channels breakout hit, The 4400. Harris had a recurring role on Showtime's hit series, Queer as Folk. He played the character of James ("Hunter") Montgomery from 2003, until the series ended its five year run in 2005. Allan's film credits include Paycheck, and the feature film A Home at the End of the World, starring Collin Farrell, Robin Wright Penn, and Sissy Spacek. Harris is featured in the 2006 movie, Final Destination 3, and was also a guest star on the new Showtime television series, Masters of Horror, which had its first airing in 2005.

Harris is not limited to just acting. He is also a singer/songwriter and lead guitarist for the band Square 9 with Dustin Sparks, (drums and vocals), and Jesse Goodall (bass, piano and vocals). The group has performed in and around the Vancouver area. Square9 has recently released their first demo CD which was recorded at Mushroom Studios in Vancouver, BC.