Sullivan began writing science fiction in the late 1970s and achieved some early prominence when he was selected to write a series of novels based on the television show, V. He subsequently published four original novels, Destiny's End (1988), The Parasite War (1989), The Martian Viking (1991) and Lords of Creation (1992).
Throughout his writing career, Sullivan has regularly published SF short stories in the genre magazines including, most often, Asimov's. He has been a finalist for the Nebula Award.
Sullivan conceived and edited two original anthologies Tropical Chills (1988) and Cold Shocks (1991).
Sullivan has also written a number of original screenplays for low-budget action movies and acted in several as well.