Heyerdahl is best known for his roles in Supernatural and Twilight. He is half Norwegian and half Scottish. He also portrays SS Obergruppenführer Ernst Kaltenbrunner in the Nuremberg TV movie starring Alec Baldwin.
He was praised by his former co-star Jensen Ackles, at the LA Supernatural Convention 2011. Ackles says that during the torture scene of Christopher's character Alastair, Ackles was thinking "Wow, I'm totally being out-acted here", after that Ackles turns to the audience and asks them "I mean, wasn't he good?" The audience replies with massive applause.
From 2007 to 2011, Heyerdahl featured prominently on the syfy network series Sanctuary, notably as Jack the Ripper, real name John Druitt. Druitt was a member of "the five," a group of scientists in Victorian Britain who obtained supernatural powers through experiments with vampire blood, Druitt's ability was teleportation.