In 2017 Knudsen starred as Vic on the television series The Mist in 2017. He has also starred in several films including The Prize Winner of Defiance, Ohio, Saw II, Bon Cop, Bad Cop, Saw V, Saw 3D, Scott Pilgrim vs the World, Scream 4, and more. He has also appeared in episodes of the TV series The Guardian, Degrassi, and more. Erik Knudsen was nominated for Saturn Awards for Best Supporting Actor on Television for Continuum in 2014, 2015, and 2016.