Kennedy is best known for his work on the TV series "Ghost Whisperer," as well as in the "Scream" film franchise.
His appearance on "Eureka" is to air as part of the show's fourth season.
The series is currently being filmed on location in Vancouver, British Columbia.
Syfy has ordered 20 episodes of the dramedy, which is to premiere July 9.
Kennedy joins a lineup of previously announced guest stars that includes Jaime Ray Newman, Matt Frewer and Wil Wheaton.