Updated: March 29, 2021

Much of Hedison's acting career has been on television. In 1961, he appeared with Geraldine Brooks (1925–1977) in an episode of ABC's Bus Stop with Marilyn Maxwell, for which Brooks was nominated for an Emmy Award. He was cast as a counter espionage agent who traveled the world as a Hollywood talent agent in the 16-episode series Five Fingers. He followed that up with a starring role as Captain Lee Crane in the ABC television version of Irwin Allen's Voyage to the Bottom of the Sea with Richard Basehart. The show ran for four years. He also had a semi-regular role on ABC's The Colbys.

In 1990, he was the series host for Phenomenal World. He appeared in the television movie A.D. as well as The Saint Family, The Love Boat, Fantasy Island, The Bob Newhart Show, Charlie's Angels, The A-Team, Knight Rider, and Wonder Woman, among many others. He played Spencer Harrison on the American soap opera Another World from 1991 to 1996. He followed that up in 2004 with a role on The Young and the Restless as Arthur Hendricks.

Fox released the first episodes of Voyage to the Bottom of the Sea on DVD on February 21, 2006, and Hedison was interviewed extensively for that release and for several subsequent releases after that through October 23, 2007. All three season releases included clips from Hedison's interview for The Fantasy Worlds of Irwin Allen in 1995. The final season was released in 2010 and 2011. The entire run was released in Region 2 DVD in the UK in 2011.

In the summer and fall of 2006 and into 2007, Hedison worked on four audio books. The first, McKnight's Memory, was first released in October 2007. The second, The King, McQueen and the Love Machine was released June 15, 2008. The third project was an 12 minute introduction to the reissue of The James Bond Lifestyle that came out June 7, 2007. His fourth audio book project, The Casino Caper, was released in August 2007.

Hedison attended the Megacon convention February 18–20, 2007. In 2009, he attended Wondercon in San Francisco in February and spent time in Spain and Italy in the late summer. He made two appearances in the Fall of 2009; the Big Apple Con Comic Con in New York City in October 16–18 and the Winter Memorabilia Show in Birmingham, UK, November 2009.

He visited England in March and appeared at two autograph shows in the Los Angeles area. In March 2011, Hedison headlined a 1960s sci-fi reunion at Monster Mania in Cherry Hill, NJ, with Lee Meriwether and Robert Colbert of Time Tunnel, Batman and Maverick and Roy Thinnes of UFO.