The actor is best known for his work in TV's Murder in the First, Studio 60 on the Sunset Strip and Wings. He will portray Brother Michael, the charismatic leader of a cult, on Helix.
"Magnetic and charming, he is a brilliant speaker and sermonizer, but also a first-class geneticist," the cable network said in a news release.
Filming for the mystery series' 13-episode sophomore season is underway in Montreal, Quebec.
Syfy said the fresh episodes will follow the doctors of the Centers for Disease Control, who are "still haunted by the Narvik outbreak and the events that took place in Arctic Biosystems, investigating a deadly outbreak of a new disease on a Windjammer cruise ship."