[4] According to his wife, Brown hated to write, and did whatever he could to put it off: play his flute, challenge a friend to a game of chess, or tease Ming Tah, his Siamese cat.

When he would finally return home to sit himself in front of the typewriter, he produced work in a variety of genres: mystery, science fiction, short fantasy, black comedy.

Brown's first mystery novel, 1947's The Fabulous Clipjoint, began a series starring Ed and Ambrose Hunter depicting how a young man gradually ripens into a detective under the tutelage of his uncle, an ex–private eye now working as a carnival concessionaire.

The Lights in the Sky Are Stars (1952) tells the story of an aging astronaut who is trying to get his beloved space program back on track after Congress has cut its funding.

The short story "Answer" (1954) is thought to be the earliest representation of the "Yes, now there is a God" science fiction trope of a supercomputer that releases itself from human control.

"[13] In his non-fiction book Danse Macabre (1981), a survey of the horror genre since 1950, writer Stephen King includes an appendix of "roughly one hundred" influential books of the period: Fredric Brown's short-story collection Nightmares and Geezenstacks is included, and is, moreover, asterisked as being among those select works King regards as "particularly important".

[4] His novel The Screaming Mimi became a 1958 film starring Anita Ekberg and Gypsy Rose Lee and directed by Gerd Oswald.

In Spain, his 1961 short story "Nightmare in Yellow" was adapted as El cumpleaños (The Birthday), the 1966 debut episode of Historias para no dormir.