Harmon joined the cast of The Bold and the Beautiful in December 1996 as only the third actor to play the second-youngest Forrester sibling. Harmon assumed the role from Jeff Trachta, who had been with the show from 1989 to the day before Harmon first appeared as Thorne. Prior to that Clayton Norcross portrayed Thorne from 1987 to 1989.
The role of Thorne Forrester is not Harmon's first daytime role. Before joining the CBS soap, Harmon appeared as Del Henry on ABC's All My Children. It had been widely rumored a few years ago that ABC might try to lure Harmon back to the show. Whether or not ABC made any sort of overture to the actor remains unknown. All My Children finally did recast the role -- but not until earlier this year.