Early career

Bernstein's first recorded credit is a five-page story in Spark Publications' Golden Lad #4, featuring the character Swift Arrow. Other early work includes text fillers for DC Comics and Fawcett Comics, as well as a 1947 Green Lantern story.

For Marvel Comics' 1950s iteration, Atlas Comics, Bernstein wrote several stories of the masked Western character Black Rider. Like most comics professionals of this time, Bernstein went largely uncredited, often receiving credit belatedly in modern-day reprints of his work.

During the 1950s, Bernstein confirmably scripted war stories for Atlas' War Comics and DC's All-American Men of War, G.I. Combat, Our Army At War, Our Fighting Forces, and Star Spangled War Stories; psychological drama in EC Comics' Psychoanalysis and Shock Illustrated; and superhero stories, working with celebrated artist Jack Kirby on at least one Green Arrow tale, in World's Finest Comics #99 (Feb. 1959).

Superman and Aquaman

Bernstein's first recorded Superman story, for DC Comics, is "The Oldest Man In Metropolis", in Action Comics #251 (April 1959). Later work include the DC titles Superman's Girl Friend, Lois Lane, Superman's Pal, Jimmy Olsen, Superboy (as well as the later Superboy feature in Adventure Comics), and features starring Green Arrow, Supergirl, and Aquaman, a 1940s Golden Age character he reintroduced with artist Ramona Fradon in Adventure Comics #260 (May 1959) and scripted through at least #282 (March 1961), introducing major characters along the way.

Later during this period historians and fans call the Silver Age of Comic Books, Bernstein scripted stories of the Archie Comics character the Fly, and, with plots by Marvel editor-in-chief Stan Lee, some of the earliest Iron Man and Thor stories, in, respectively Tales of Suspense and Journey into Mystery. He also scripted some Human Torch stories, plotted by penciler Jack Kirby, in Strange Tales.

Bernstein's last known original DC story is "King Superman versus Clark Kent, Metallo" in Action Comics #312 (May 1964). Bernstein adapted the famed radio character The Shadow for Archie Comics that same year, and his last known comics work are the two stories in The Shadow #3 (Nov. 1964).