He used a variety of pen-names, including Cecil Corwin, S. D. Gottesman, Edward J. Bellin, Kenneth Falconer, Walter C. Davies, Simon Eisner, Jordan Park, Arthur Cooke, Paul Dennis Lavond, and Scott Mariner.

While a member of the Futurians, he met and became friends with Frederik Pohl, Donald A. Wollheim, Robert A. W. Lowndes, and his future wife Mary Byers.

In 1951 he started writing full-time,[5] returning to the East Coast where he collaborated on novels with his old Futurian friends Frederik Pohl and Judith Merril.

His other short fiction includes "The Little Black Bag", "The Marching Morons", "The Altar at Midnight", "MS. Found in a Chinese Fortune Cookie", "Gomez" and "The Advent on Channel Twelve".

"The Marching Morons" is a look at a far future in which the world's population consists of five billion idiots and a few million geniuses – the precarious minority of the "elite" working desperately to keep things running behind the scenes.

[10] Biographer Mark Rich describes the 1958 story "Two Dooms" as one of several stories which are "concern[ed] with the ethics of theoretical science" and which "explore moral quandaries of the atomic age": "Two Dooms" follows atomic physicist Edward Royland on his accidental journey into an alternative universe where the Nazis and Japanese rule a divided United States.

In his own world, Royland debated whether to delay progress at the Los Alamos nuclear research site or to help the atomic bomb achieve its terrifying result.

[11] The Space Merchants contributed significantly to the maturing and to the wider academic respectability of the science fiction genre, not only in America but also in Europe.

On a day when he was due to meet with Bob Mills in New York City to interview for the position of editor of The Magazine of Fantasy & Science Fiction,[14] he was delayed because he had to shovel snow from his driveway.

Kornbluth, for example, decided to educate himself by reading his way through an entire encyclopedia from A to Z; in the course of this effort, he acquired a great deal of esoteric knowledge that found its way into his stories, in alphabetical order by subject.

"[9] Kornbluth's name is mentioned in Lemony Snicket's Series of Unfortunate Events as a member of V.F.D., a secret organization dedicated to the promotion of literacy, classical learning, and crime prevention.