Oksner's early work includes creating the second version of Marvel Boy in 1943 for Timely Comics, the 1930s-'40s predecessor of Marvel Comics. He went on to write and draw the syndicated newspaper comic strip Miss Cairo Jones (1945-1947), after which DC editor Sheldon Mayer hired him as an artist on comics adapted from other media. There, he moved from adventure strips to teen-oriented strips. Oksner's work in this field included Adventures of Dean Martin and Jerry Lewis and its successor, Adventures of Jerry Lewis; Adventures of Bob Hope; The Many Loves of Dobie Gillis; Sgt. Bilko; Pat Boone; Angel and the Ape;Welcome Back, Kotter; Elvira's House of Mystery, the highly-regarded Stanley and His Monster and for King Features, the newspaper comic 'I Love Lucy'.
When the demand for the kind of comic books he had earlier produced fell off in the 1970s, Oksner began drawing such DC superhero series as Superman,Supergirl, Wonder Woman, Shazam!, Black Orchid, Lois Lane, Ambush Bug, and others. He retired from comics in 1986.
Oksner's other work in comic strips included succeeding Gus Edson as writer of artist-creator Irwin Hasen's Dondi for a time beginning in 1965; and drew and co-creator Soozi (1967), with Don Weldon.