According to Bruce Lanier Wright, "Palmer was hit by a truck at age seven and suffered a broken back." An unsuccessful operation on Palmer's spine stunted his growth (he stood about four feet tall), and left him with a hunchback.

Palmer found refuge in science fiction, which he read voraciously. He rose through the ranks of science fiction fandom and is credited, along with Walter Dennis, with editing the first fanzine, The Comet, in May, 1930.

Ziff-Davis acquired Amazing Stories in 1938. The publisher sacked then editor T. Connor O'Sloane and, on the recommendation of popular author Ralph Milne Farley, offered the editorship to Palmer. In 1939, Palmer began a companion magazine to Amazing Stories titled Fantastic Adventures, which lasted until 1953.

When Ziff-Davis moved its magazine production from Chicago to New York City in 1949, Palmer resigned and, with Curtis Fuller, another Ziff-Davis editor who did not want to leave the midwest, founded Clark Publishing Co.

Science Fiction magazines

As an editor, Palmer tended to favor adventurous, fast-moving space opera-type stories. His tenure at Amazing Stories was notable for his purchase of Isaac Asimov's first professional story, "Marooned Off Vesta".

Palmer was also known for his support of the long running and controversial Shaver Mystery stories, based around a series of stories by Richard S. Shaver. Palmer's support of the truth of Shaver's stories (which maintained that the world is dominated by insane inhabitants of the hollow earth), was controversial in the science fiction community. It is unclear whether Palmer believed in the literal truth of the Shaver stories, or if he was using the standpoint of his own belief to promote the concept to his readership.

Palmer began his own science fiction publishing ventures while working for Ziff-Davis, eventually leaving the company to form his own publishing house, Clark Publishing Company, which was responsible for the titles Imagination and Other Worlds, among others. None of these magazines achieved the success of Amazing Stories during the Palmer years, but Palmer published Space World magazine until his death.

Paranomality magazines

In 1948, Palmer and Curtis Fuller co-founded Fate, which covered divination methods, Fortean events, belief in the survival of personality after death, predictive dreams, accounts of ghosts, mental telepathy, archaeology, flying saucer sightings, cryptozoology, alternative medicine, warnings of death, and other paranormal topics, many contributed by readers.

Curtis Fuller and his wife Mary took full control of Fate in 1955, when Palmer sold his interest in the venture. The magazine has continued in publication under a series of editors and publishers to the present day.

Another paranormal magazine Palmer created along the line of Fate was the short-lived Mystic magazine .

In the 1970s, Palmer also published Ray Palmer's News Letter which was combined into another of his publications called Forum in March 1975.

UFO magazine

In the first issue of Fate, Palmer published Kenneth Arnold's report of "flying discs." Arnold's sighting marked the beginning of the modern UFO era, and his story propelled the fledgling Fate to national recognition. Through Fate, Palmer was instrumental in popularizing belief in flying saucer. This interest led him to establish the magazine Flying Saucers.

The secret identity of DC Comics superhero the Atom - introduced by science fiction writer Gardner Fox in 1961 - is named after Palmer.