Born in New Jersey in 1946, Weinberg sold his first story in 1967, and has been writing for the last few decades. Most of his writing career was conducted part-time while also owning a bookstore; he became a full-time writer after 1997.

Weinberg is also an editor, and has edited books in the fields of horror, science fiction and western.

From 1970 to 1981, Weinberg edited 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.

In comics, Weinberg has written 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 sits on the ‘Council of Six’, a board of editorial advisers for Canadian publisher Battered Silicon Dispatch Box. Along with another boardmember, George Vanderburgh, it has recently been announced that Weinberg will take the editorial reins at Arkham House. Weinberg is a graduate of Stevens Institute of Technology.

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.