Trumbo was born in Montrose, Colorado, and graduated from Grand Junction High School. While still in high school, he worked as a cub reporter for the Grand Junction Daily Sentinel, covering courts, the high school, the mortuary and civic organizations. He attended the University of Colorado at Boulder for two years (the central fountain at the University was named the Dalton Trumbo Free Speech Fountain in his honor in the mid-1990s), working as a reporter for the Boulder Daily Camera and contributing to the campus humor magazine, the yearbook and the campus newspaper.He got his start working for Vogue magazine.

His first published novel, Eclipse, was about a town and its people, written in the social realist style, and drew on his years in Grand Junction. The book was very controversial in Grand Junction and helped give him an infamous reputation in this city. Years after his death he would be honored with a statue in front of the Avalon Theater on Main Street, depicted writing a screenplay in a bathtub.

He started in movies in 1937; by the 1940s, he was one of Hollywood's highest paid writers for work on such films as Thirty Seconds Over Tokyo (1944), Our Vines Have Tender Grapes (1945), and Kitty Foyle (1940), for which he was nominated for an Academy Award for Writing Adapted Screenplay.

Trumbo's 1939 anti-war novel, Johnny Got His Gun, won a National Book Award (then known as an American Book Sellers Award) that year. The novel was inspired by an article Trumbo had read about a Canadian soldier who had lost all his limbs in World War I and was visited in hospital by the Prince of Wales.

Trumbo aligned himself with the Communist Party USA before the 1940s, although he did not join the party until later. After the outbreak of World War II in 1939, American communists argued that the United States should not get involved in the war on the side of Great Britain, since the Molotov-Ribbentrop Pact of nonaggression meant that the Soviet Union was at peace with Germany. In 1941, Trumbo wrote a novel The Remarkable Andrew, in which, in one scene, the ghost of Andrew Jackson appears in order to caution the United States not to get involved in the war. In a review of the book, Time Magazine sarcastically wrote, "General Jackson's opinions need surprise no one who has observed George Washington and Abraham Lincoln zealously following the Communist Party Line in recent years."

Shortly after the 1941 German invasion of the Soviet Union, Trumbo and his publishers decided to suspend reprinting of Johnny Got His Gun until the end of the war. After receiving letters from individuals requesting copies of the book, Trumbo contacted the FBI and turned these letters over to them. Thus did Trumbo, in effect, "name names", something that would come back to haunt him years later when others would name him before the House Un-American Committee. Trumbo regretted this decision, which he called "foolish", after two FBI agents showed up at his home and it became clear that "their interest lay not in the letters but in me."

Trumbo was a member of the Communist Party USA from 1943 until 1948. He bragged in The Daily Worker that among the films that communist influence in Hollywood had quashed were adaptations of Arthur Koestler's anti-communist works Darkness at Noon and The Yogi and the Commissar. Hollywood's Missing Movies: Why American films have ignored life under communism. - Reason Magazine

Blacklisting

During the McCarthy Era in 1947, Trumbo, along with nine other writers and directors, was called before the House Un-American Activities Committee as an unfriendly witness to testify on the presence of communist influence in Hollywood. Trumbo refused to give information. After conviction for contempt of Congress, he was blacklisted, and in 1950, spent 11 months in prison in the federal penitentiary in Ashland, Kentucky.

After Trumbo was blacklisted, some Hollywood actors and directors, such as Elia Kazan and Clifford Odets, agreed to testify and to provide names of fellow communist party members to Congress. Many of those who testified were immediately ostracized and shunned by their former friends and associates. However, Trumbo always maintained that those who testified under pressure from HUAC and the studios were equally victims of the Red Scare, an opinion for which he was criticized.

After completing his sentence, Trumbo and his family moved to Mexico with Hugo Butler and his wife Jean Rouverol, who had also been blacklisted. There, Trumbo wrote thirty scripts under pseudonyms, such as the co-written Gun Crazy (1950) (Millard Kaufman acted as a "front" for Trumbo).

With the support of Otto Preminger, he received credit for the 1960 film Exodus. Shortly thereafter, Kirk Douglas made public Trumbo's credit for the screenplay for Spartacus, an event which has been cited as the beginning of the end of the blacklist. Trumbo was reinstated in the Writers Guild of America, West, and was credited on all subsequent scripts.

In 1971, Trumbo directed the film adaptation of Johnny Got His Gun, which starred Timothy Bottoms, Diane Varsi and Jason Robards.

One of his last films, Executive Action, was based on various conspiracy theories about the Kennedy assassination.

His account and analysis of the Smith Act trials is entitled The Devil in the Book.

He won an Oscar for The Brave One (1956), written under the name Robert Rich. In 1975, the Academy officially recognized Trumbo as the winner and presented him with a statuette.

In 1993, Trumbo was posthumously awarded the Academy Award for writing Roman Holiday (1953). The screen credit and award were previously given to Ian McLellan Hunter, who had been a "front" for Trumbo.

He died in Los Angeles of a heart attack at the age of 70 on September 10, 1976.

Trumbo had three children: one son, filmmaker Christopher; and two daughters, photographer Melissa, known as Mitzi, and psychotherapist Nikola. Mitzi once had a relationship with actor/comedian Steve Martin; Martin later confessed that, at that time in his "tunnel-visioned life," he had never heard of her father. In his memoir, Born Standing Up, Martin credits his time spent with the Trumbo family as having aroused his interest in politics and art.

Selected film works:

• Road Gang, 1936
• Love Begins at 20, 1936
• Devil's Playground, 1937
• Fugitives for a Night, 1938
• A Man to Remember, 1938
• Five Came Back, 1939 (with Nathanael West and J. Cody)
• Curtain Call, 1941
• Bill of Divorcement, 1940
• Kitty Foyle, 1940
• The Remarkable Andrew, 1942
• Tender Comrade, 1944
• A Guy Named Joe, 1944
• Thirty Seconds Over Tokyo, 1944
• Our Vines Have Tender Grapes, 1945
• Gun Crazy, 1950 (co-writer, front Millard Kaufman)
• He Ran All the Way, 1951 (co-writer, front Guy Endore)
• The Prowler, 1951 (uncredited with Hugo Butler)
• Roman Holiday, 1953 (front Ian McLellan Hunter)
• They Were So Young, 1954, (pseudonym: Felix Lutzkendorf)
• The Boss, 1956 (front: Ben L. Perry)
• The Brave One, 1956 (front Robert Rich)
• The Green-eyed Blonde, 1957 (front: Sally Stubblefield)
• From the Earth to the Moon, 1958 (co-writer as front: James Leicester)
• Cowboy (1958) (front: Edmund H. North)
• Spartacus, 1960, dir. by Stanley Kubrick
• Exodus, 1960 (based on Leon Uris' 1958 novel of the same name)
• The Last Sunset, 1961
• Lonely are the Brave, 1962
• The Sandpiper, 1965
• Hawaii, 1966 (based on the novel by James Michener, 1959)
• The Fixer, 1968
• Johnny Got His Gun, 1971 (also directed)
• The Horsemen, 1971
• F.T.A., 1972
• Executive Action, 1973
• Papillon, 1973 (based on the novel by Henri Charrière, 1969)

Novels, plays and essays:

• Eclipse, 1935
• Washington Jitters, 1936
• Johnny Got His Gun, 1939
• The Remarkable Andrew, 1940 (also known as Chronicle of a Literal Man)
• The Biggest Thief in Town, 1949 (lay)
• The Time Out of the Toad, 1972 (essays)
• Night of the Aurochs, 1979 (unfinished, ed. R. Kirsch)

Non-fiction:

• Harry Bridges, 1941
• The Time of the Toad, 1949
• The Devil in the Book, 1956
• Additional Dialogue: Letters of Dalton Trumbo, 1942—62, 1970 (ed. by H. Manfull)