Horn voiced the role of Kaniehtí:io, the Native American protagonist's (Ratohnhake:ton) Mohawk mother, in the 2012 video game, Assassin's Creed III, developed by Ubisoft. She wrote and directed her debut film that year, The Smoke Shack, in association with the National Screen Institute. In 2013, Horn played Rynn, an Irathient Spirit Rider, on the Syfy TV series, Defiance, and played Dorothy from The Wizard of Oz in "Slumber Party", an episode of the CW series Supernatural. She also appeared in Embrace of the Vampire starring Sharon Hinnendael, a remake of the 1995 horror film of the same name, in the television special Gavin Crawford's Wild West and in the Amazon series The Man in the High Castle.