His notable TV work includes producing or writing, or both, for The Outer Limits, Eerie, Indiana, Beverly Hills, 90210, and The Twilight Zone.
In the early 1990s Cassutt worked as a writer and producer for WIOU, an ensemble drama starring John Shea and Helen Shaver, and then for Eerie, Indiana.
From 1992 to 1993 Cassutt was producer and writer for the ABC police drama Sirens; he later wrote the two-part premiere of the show's syndicated version with series creator Ann Lewis Hamilton.
He has developed scripts based on classic science fiction works by writers such as Arthur C. Clarke, Robert A. Heinlein, Clifford Simak, and Philip Jose Farmer.
Cassutt has also appeared on camera in two History Channel documentaries, Disasters in Space, in 1999, and Star City, in 2002, as well as a 2002 BBC special about astronauts and test pilots.
His adaptation of Howard Waldrop's Nebula Award-winning novelette The Ugly Chickens was filmed as a short starring Felicia Day and directed by Mark Raso in Toronto, Summer 2023.
With Andrew M. Greeley, he co-edited an anthology of science fiction and fantasy stories with Catholic themes, entitled Sacred Visions, also published by Tor in 1991.
His historical thriller, Red Moon, a novel of the dark side of the space race between America and the Soviet Union, appeared in March 2001 and became the subject of an entire article in Asimov's Science Fiction, written by novelist Norman Spinrad.
The book contains biographies and photos of seven hundred astronauts and cosmonauts from around the world, for which Cassutt conducted dozens of interviews over a period of ten years.