Born in New Jersey in 1946, Weinberg sold his first story in 1967. Most of his writing career was conducted part-time while also owning a bookstore; he became a full-time writer after 1997.
Weinberg was also an editor, and edited books in the fields of horror, science fiction and western.
Weinberg graduated from Stevens Institute of Technology.
From 1970 to 1981, Weinberg edited and published Pulp, a fanzine devoted to pulp magazines; Pulp became
noted for its interviews with pulp writers such as Walter B. Gibson and
Frederick C. Davis. He also published the Pulp Classics, Lost Fantasy, Weird Menace, and Incredible Adventures series of pulp reprints at the same time.
In comics, Weinberg wrote for Marvel Comics; his first job was on the series Cable, and he later created the series Nightside starring Sydney Taine a character who had previously appeared in a short story Weinberg wrote.
Weinberg sat on the 'Council of Six', a board of editorial advisers for Canadian publisher Battered Silicon Dispatch Box. Along with another boardmember, George Vanderburgh, Weinberg took the editorial reins at Arkham House.
At Chicon 7, Weinberg received a Special Committee Award for his service to science fiction, fantasy, and horror. Due to health issues, Weinberg was unable to attend and the award was accepted on his behalf by Jane Frank. He died in Oak Forest, Illinois on September 25, 2016 at the age of 70.