His first science fiction story, "Not Yet the End" was published in Captain Future in 1941. Many of the stories which followed are short, practically extended jokes rather than actual stories. Nevertheless, Brown wrote with an engaging style.
Humor carried over into his novels as well. His science fiction novel What Mad Universe (1949) plays with the clichéd conventions of the genre by throwing a pulp magazine editor into a parallel world based, not on the adventure stories he published, but rather on a child's image of those stories and the man who published them. Similarly, Martians, Go Home (1955) looks at a Martian invasion through the eyes of a science fiction author.
One of his most famous short stories, "Arena" was used as the basis for a popular episode of Star Trek.
His work includes:
- THE FABULOUS CLIPJOINT (1947), Edgar Award winner for best first novel
- THE SCREAMING MIMI (1949), ISBN 0881844497
- WHAT MAD UNIVERSE (1949)
- NIGHT OF THE JABBERWOCK (1950)
- SPACE ON MY HANDS (1953), ISBN 0899683320
- THE LIGHTS IN THE SKY ARE STARS (1953)
- MARTIANS, GO HOME (1955), which was the basis for an arguably below-par 1990 movie of the same name, starring Randy Quaid and Margaret Colin
- THE LENIENT BEAST (1956), ISBN 0881844446
- ROGUE IN SPACE (1957)
- KNOCK THREE-ONE-TWO (1959)
- THE MIND THING (1961)
- FROM THESE ASHES: THE COMPLETE SHORT SF OF FREDRIC BROWN (2001), ISBN 1-886778-18-3
- MARTIANS AND MADNESS (2002), ISBN: 1-886778-17-5