McNulty was born in Penticton, British Columbia, Canada. He has acted in three aviation movies: Falling from the Sky: Flight 174 with William Devane, Final Descent with Robert Urich, and Snakes on a Plane with Samuel L. Jackson. He had a supporting role alongside Roger Moore and Nancy Allen in Bill Condon's The Man Who Wouldn't Die (1995).

McNulty also appeared in the 2009 remake of The Uninvited, where he worked alongside A Series of Unfortunate Events' Emily Browning. He also played The Reverend Roy Le Grange in the "Supernatural" TV episode "Faith".