Kornbluth was born and grew up in Inwood in New York City. As a teenager, he became a member of the Futurians, the influential group of science fiction fans and writers. While a member of the Futurians, he met and became friends with Isaac Asimov, Frederik Pohl, Donald A. Wollheim, Robert A. W. Lowndes, and his future wife Mary Byers. He also participated in the Fantasy Amateur Press Association.

Kornbluth served in the US Army during World War II (European Theatre). He received a Bronze Star for his service in the Battle of the Bulge, where he served as a member of a heavy machine gun crew. Upon his discharge, he returned to finish his education, which had been interrupted by the war, at the University of Chicago.

Kornbluth began writing at fifteen. His first solo story, "The Rocket of 1955," was published in Richard Wilson's fanzine Escape (Vol 1 No 2, August 1939); his first collaboration, "Stepsons of Mars," written with Richard Wilson and published under the name "Ivar Towers," appeared in the April 1940 Astonishing. 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 12."

"MS. Found in a Chinese Fortune Cookie" (1957) is purportedly written by Kornbluth from notes by "Cecil Corwin" who has been declared insane and incarcerated, from where he is smuggling out in fortune cookies the ultimate secret of life. This fate was Kornbluth's response to the unauthorised publication of "Mask of Demeter" (as by "Corwin" and "Martin Pearson" Donald A. Wollheim) in 1953.

"The Little Black Bag" was first televised as a live act on the television show "Tales of Tomorrow" on May 30, 1952. It was later adapted for television by the BBC in 1969 for its Out of the Unknown series. In 1970, the same story was adapted by Rod Serling for an episode of his Night Gallery series. This dramatization starred Burgess Meredith as the alcoholic Dr. Full, who has lost his license and become a derelict. He finds a bag containing advanced medical technology from the future, which, after an unsuccessful attempt to pawn it, he uses benevolently ... reclaiming his career and redeeming his soul...but not that of the guttersnipe he takes in as his receptionist/assistant.

"The Marching Morons" is one of Kornbluth's most famous short stories; it is a satirical 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. Part of its appeal is that readers identify with the beleaguered geniuses (which is entirely compatible with science fiction fans' broadly held opinion of their relationship with the mundane majority). Some believe that "The Marching Morons" is a direct sequel to "The Little Black Bag": it is easy to miss this, as "Bag" is set in the contemporary present while "Morons" takes place several centuries from now, and there is no character who appears in both stories. The titular black bag in the first story is actually an artifact from the time period of "The Marching Morons": a medical kit filled with self-driven instruments enabling a far-future moron to "play doctor." A similar concept to "The Marching Morons" is used in the final stages of Search the Sky.

Many of Kornbluth's novels were written as collaborations: either with Judith Merril (using the pseudonym Cyril Judd), or with Frederik Pohl. By far the most successful and important of these were the novels Gladiator-At-Law and The Space Merchants. 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. Kornbluth also wrote several novels under his own name, the most successful being The Syndic and Not This August.

Kornbluth died at age thirty-four in Levittown, New York. Scheduled to meet with Bob Mills in New York City, Kornbluth had to shovel out his driveway, which left him running behind. Racing to make his train, he suffered a heart attack on the platform of the train station.

A number of short stories remained unfinished at Kornbluth's death; these were eventually completed and published by Pohl. One of these stories, "The Meeting" (The Magazine of Fantasy and Science Fiction, November 1972), was the co-winner of the 1973 Hugo Award for Best Short Story; it tied with R. A. Lafferty's "Eurema's Dam." Almost all of Kornbluth's solo SF stories have been collected as His Share of Glory: The Complete Short Science Fiction of C. M. Kornbluth (NESFA Press, 1997).

Pohl, in his autobiography The Way the Future Was, Damon Knight, in his memoir The Futurians, and Isaac Asimov, in his memoirs In Memory Yet Green and I. Asimov: A Memoir, all give vivid descriptions of Kornbluth as a man of odd personal habits and vivid eccentricities. Among the traits which they describe:

• Kornbluth 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. When Kornbluth wrote a story that mentioned the ancient Roman weapon ballista, Pohl knew that Kornbluth had finished the "A" volume and had started the "B".
• According to Pohl, Kornbluth never brushed his teeth, and they were literally green. Deeply embarrassed by this, Kornbluth developed the habit of holding his hand in front of his mouth when speaking.
• Kornbluth disliked black coffee, but felt obliged to acquire a taste for it because he believed that professional authors were "supposed to" drink black coffee. He trained himself by putting gradually less cream into each cup of coffee he drank, until he eventually "weaned himself" (Knight's description) and switched to black coffee.

Novels

• Outpost Mars (1952) (with Judith Merril, writing as Cyril Judd), first published as a Galaxy serial entitled Mars Child (May-July 1951) and later reprinted as Galaxy novel #46 retitled Sin in Space (1961).
• The Space Merchants (1952) (with Frederik Pohl), first published as a Galaxy serial entitled Gravy Planet (June-August 1952)
• Gunner Cade (1952) (with Judith Merril, writing as Cyril Judd, first published as an Astounding Science Fiction serial (March-May 1952))
• Takeoff (1952)
• The Syndic (1953) Winner of the Prometheus Award
• Search the Sky (1954) (with Frederik Pohl) substantially revised by Pohl (1985)
• Gladiator at Law (1955) (with Frederik Pohl, first published as a Galaxy serial (June-August 1954)) revised by Pohl (1986)
• Wolfbane (1959) (with Frederik Pohl) (first published as a Galaxy serial (Oct-Nov 1957)) substantially rewritten by Pohl (1986)
• Not This August (1955) (AKA Christmas Eve) revised by Pohl (1981)
• Venus, Inc. (1985) (with Frederik Pohl; this is an omnibus edition of The Space Merchants (1952) and Pohl's solo novel, The Merchant’s War (1984))

Collections

• The Explorers (1954)
• "Foreword," [Frederik Pohl]
• "Gomez," [original here]
• "The Mindworm," 1950
• "The Rocket of 1955," 1939
• "The Altar at Midnight," 1952
• "Thirteen O’Clock" [as by Cecil Corwin], (1941) "Peter Packer" series
• "The Goodly Creatures," 1952
• "Friend to Man," 1951
• "With These Hands," 1951
• "That Share of Glory," 1962
• The Mindworm and other stories (1955)
• "The Mindworm," (1950)
• "Gomez," 1954
• "The Rocket of 1955," 1939
• "The Altar at Midnight," 1952
• "The Little Black Bag," 1950
• "The Goodly Creatures," 1952
• "Friend to Man," 1951
• "With These Hands," 1951
• "That Share of Glory," 1952
• "The Luckiest Man in Denv" [as by Simon Eisner], · 1952
• "The Silly Season," 1950
• "The Marching Morons · nv Galaxy Apr ’51
• A Mile Beyond the Moon (1958) [abridged for its 1962 paperback reprint, see below]
• "Make Mine Mars," 1952
• "The Meddlers," 1953 [not in 1962 paperback]
• "The Events Leading Down to the Tragedy," 1958
• "The Little Black Bag," 1950 (related to "The Marching Morons")
• "Everybody Knows Joe," 1953
• "Time Bum," 1953
• "Passion Pills," [original here] [not in 1962 paperback]
• "Virginia," 1958
• "The Slave," 1957 [not in 1962 paperback]
• "Kazam Collects" [as by S. D. Gottesman], 1941
• "The Last Man Left in the Bar," 1947
• "The Adventurer," 1953
• "The Words of Guru" [as by Kenneth Falconer], 1941
• "Shark Ship" ["Reap the Dark Tide"], 1958
• "Two Dooms," 1958 [not in 1962 paperback]
• The Marching Morons and other Science Fiction Stories (1959)
• "The Marching Morons," 1951
• "Dominoes," 1953
• "The Luckiest Man in Denv" [as by Simon Eisner], 1952
• "The Silly Season," 1950
• "MS. Found in a Chinese Fortune Cookie," 1957
• "The Only Thing We Learn," 1949
• "The Cosmic Charge Account," 1956
• "I Never Ast No Favors," 1954
• "The Remorseful," 1953
• The Wonder Effect (1962) (with Frederik Pohl)
• "Introduction,"
• "Critical Mass," 1962
• "A Gentle Dying," 1961
• "Nightmare with Zeppelins," 1958
• "Best Friend" [as by S. D. Gottesman], 1941
• "The World of Myrion Flowers," 1961
• "Trouble in Time" [as by S. D. Gottesman], 1940
• "The Engineer," 1956
• "Mars-Tube [as by S. D. Gottesman]," 1941
• "The Quaker Cannon," 1961
• Best Science Fiction Stories of C. M. Kornbluth (1968)
• "Introduction," [Edmund Crispin]
• "The Unfortunate Topologist," 1957 (poem)
• "The Marching Morons," 1951
• "The Altar at Midnight," 1952
• "The Little Black Bag," 1950
• "The Mindworm," 1950
• "The Silly Season," 1950
• "I Never Ast No Favors," 1954
• "Friend to Man," 1951
• "The Only Thing We Learn," 1949
• "Gomez," 1954
• "With These Hands," 1951
• "Theory of Rocketry," 1958
• "That Share of Glory," 1952
• Thirteen O'Clock and other Zero Hours (1970) (edited by James Blish) stories published originally as by "Cecil Corwin" plus "MS. Found in a Chinese Fortune Cookie" (see above)
• "Preface," [James Blish]
• "Thirteen O’Clock [combined version of the "Peter Packer" stories, “Thirteen O’Clock” and “Mr. Packer Goes to Hell”, both 1941]," [first combined appearance here]
• "The Rocket of 1955," 1939
• "What Sorghum Says" [as by Cecil Corwin], 1941
• "Crisis!" [as by Cecil Corwin], 1942
• "The Reversible Revolutions" [as by Cecil Corwin], 1941
• "The City in the Sofa" [as by Cecil Corwin], 1941
• "The Golden Road" [as by Cecil Corwin], 1942
• "MS. Found in a Chinese Fortune Cookie," 1957
• The Best of C. M. Kornbluth (1976)
• "An Appreciation," [Frederik Pohl]
• "The Rocket of 1955," 1939
• "The Words of Guru" [as by Kenneth Falconer], 1941
• "The Only Thing We Learn," 1949
• "The Adventurer," 1953
• "The Little Black Bag," 1950
• "The Luckiest Man in Denv" [as by Simon Eisner], 1952
• "The Silly Season," 1950
• "The Remorseful," 1953
• "Gomez," 1954
• "The Advent on Channel Twelve," 1958
• "The Marching Morons," 1951
• "The Last Man Left in the Bar," 1957
• "The Mindworm," 1950
• "With These Hands," 1951
• "Shark Ship" [“Reap the Dark Tide”], 1958
• "Friend to Man," 1951
• "The Altar at Midnight," 1952
• "Dominoes," 1953
• "Two Dooms," 1958
• Critical Mass (1977) (with Frederik Pohl)
• "Introduction," (Pohl)
• "The Quaker Cannon," 1961
• "Mute Inglorious Tam," 1974
• "The World of Myrion Flowers," 1961
• "The Gift of Garigolli," 1974
• "A Gentle Dying," 1961
• "A Hint of Henbane," 1961
• "The Meeting," 1972
• "The Engineer," 1956
• "Nightmare with Zeppelins," 1958
• "Critical Mass," 1962
• "Afterword," (Pohl)
• Before the Universe (1980) (with Frederik Pohl)
• "Mars-Tube" [as by S. D. Gottesman (with Frederik Pohl)], 1941
• "Trouble in Time" [as by S. D. Gottesman (with Frederik Pohl)], 1940
• "Vacant World" [as by Dirk Wylie (with Dirk Wylie, and Frederik Pohl)], 1940
• "Best Friend" [as by S. D. Gottesman (with Frederik Pohl)], 1941
• "Nova Midplane" [as by S. D. Gottesman (with Frederik Pohl)], 1940
• "The Extrapolated Dimwit" [as by S. D. Gottesman (with Frederik Pohl)], 1942
• The Best of Frederik Pohl and C.M. Kornbluth (1987) (with Frederik Pohl)
• "Introduction," (Pohl)
• "The Stories of the Sixties," (Pohl, section introduction)
• "Critical Mass," 1962
• "The World of Myrion Flowers," 1961
• "The Engineer," 1956
• "A Gentle Dying," 1961
• "Nightmare with Zeppelins," 1958
• "The Quaker Cannon," 1961
• "The 60/40 Stories," (Pohl, section introduction)
• "Trouble in Time" [as by S. D. Gottesman], 1940
• "Mars-Tube" [as by S. D. Gottesman], 1941
• "Epilogue to The Space Merchants," (Pohl, section introduction)
• "Gravy Planet," (extract from the magazine serial, not used in the book)
• "The Final Stories," (Pohl, section introduction)
• "Mute Inglorious Tam," 1974
• "The Gift of Garigolli," 1974
• "The Meeting," 1972
• "Afterword," (Pohl)
• His Share of Glory: The Complete Short Science Fiction of C.M. Kornbluth (1997) — this includes almost all of Kornbluth's solo fiction, but does not include all of the collaborative pseudonymous works which were published among his earliest work between 1940 and 1942, some of which were published in Before the Universe (1980).
• "Cyril," [Frederik Pohl]
• "Editor’s Introduction," [Timothy P. Szczesuil]
• "That Share of Glory," 1952
• "The Adventurer," 1952
• "Dominoes," 1953
• "The Golden Road" [as by Cecil Corwin], 1942
• "The Rocket of 1955," 1939
• "The Mindworm," 1950
• "The Education of Tigress McCardle," 1957
• "Shark Ship" [“Reap the Dark Tide”], 1958
• "The Meddlers," 1953
• "The Luckiest Man in Denv" [as by Simon Eisner], 1952
• "The Reversible Revolutions [as by Cecil Corwin], 1941
• "The City in the Sofa" [as by Cecil Corwin], 1941
• "Gomez," 1954
• "Masquerade" [as by Kenneth Falconer], 1942
• "The Slave," 1957
• "The Words of Guru" [as by Kenneth Falconer], 1941
• "Thirteen O’Clock" [as by Cecil Corwin], 1941
• "Mr. Packer Goes to Hell" [as by Cecil Corwin], 1941
• "With These Hands," 1951
• "Iteration," 1950
• "The Goodly Creatures," 1952
• "Time Bum," 1953
• "Two Dooms," 1958
• "Passion Pills," 1958
• "The Silly Season," 1950
• "Fire-Power" [as by S. D. Gottesman], 1941
• "The Perfect Invasion" [as by S. D. Gottesman], 1942
• "The Adventurers," 1955
• "Kazam Collects" [as by S. D. Gottesman], 1941
• "The Marching Morons," 1951
• "The Altar at Midnight," 1952
• "Crisis!" [as by Cecil Corwin], 1942
• "Theory of Rocketry," 1958
• "The Cosmic Charge Account," 1956
• "Friend to Man," 1951
• "I Never Ast No Favors," 1954
• "The Little Black Bag," 1950
• "What Sorghum Says" [as by Cecil Corwin], 1941
• "MS. Found in a Chinese Fortune Cookie," 1957
• "The Only Thing We Learn," 1949
• "The Last Man Left in the Bar," 1957
• "Virginia," 1958
• "The Advent on Channel Twelve," 1958
• "Make Mine Mars," 1952
• "Everybody Knows Joe," 1953
• "The Remorseful," 1953
• "Sir Mallory’s Magnitude" [as by S. D. Gottesman], 1941
• "The Events Leading Down to the Tragedy," 1958
• "King Cole of Pluto" [as by S. D. Gottesman], 1940
• "No Place to Go" [as by Edward J. Bellin], 1941
• "Dimension of Darkness" [as by S. D. Gottesman], 1941
• "Dead Center" [as by S. D. Gottesman], 1941
• "Interference" [as by Walter C. Davies], 1941
• "Forgotten Tongue" [as by Walter C. Davies], 1941
• "Return from M-15" [as by S. D. Gottesman], 1941
• "The Core" [as by S. D. Gottesman], 1942

Non-science fiction

• The Naked Storm (1952, as Simon Eisner)
• Valerie (1953, as Jordan Park), a novel about a girl accused of witchcraft
• Half (1953, as Jordan Park), a novel about an intersex person
• A Town is Drowning (1955, with Frederik Pohl)
• Presidential Year (1956, with Frederik Pohl)
• Sorority House (1956, with Frederik Pohl, as Jordan Park), a lesbian pulp novel
• A Man of Cold Rages (1958, as Jordan Park), a novel about an ex-dictator

Uncollected Short Stories

• "Stepsons of Mars," (1940) [as "Ivar Towers" (with Richard Wilson)
• "Callistan Tomb," (1941) [as "Paul Dennis Lavond" (with Frederik Pohl)]
• "The Psychological Regulator," (1941) [as "Arthur Cooke" (with Elsie Balter {later Elsie Wollheim}, Robert A. W. Lowndes, John Michel, Donald A. Wollheim)
• "The Martians are Coming," (1941) [as "Robert A W Lowndes" (with Robert A. W. Lowndes)]
• "Exiles of New Planet," (1941) [as "Paul Dennis Lavond" (with Frederik Pohl, Robert A. W. Lowndes, Dirk Wylie)]
• "The Castle on the Outerplanet," (1941) [as "S D Gottesman" (with Frederik Pohl, Robert A. W. Lowndes)]
• "A Prince of Pluto," (1941) [as "S D Gottesman" (with Frederik Pohl)]
• "Einstein's Planetoid," (1941) [as "Paul Dennis Lavond" (with Frederik Pohl, Robert A. W. Lowndes, Dirk Wylie)]
• "An Old Neptunian Custom," (1942) [as "Scott Mariner" (with Frederik Pohl)]

Collected and uncollected Articles

• "A Funny Article on the Convention," (1939)
• "New Directions," (1941) [as "Walter C. Davies"]
• "The Failure of the Science Fiction Novel as Social Criticism," in The Science Fiction Novel: Imagination and Social Criticism, ed. Basil Davenport, Advent Press, 1959. (pages 64-101)

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.