Irving grew up in New York City, the son of Dorothy and Jay Irving, a magazine cover artist and the creator of the syndicated comic strip Pottsy, about a New York policeman. After graduating in 1947 from Manhattan's High School of Music and Art, Irving attended Cornell University, had a two-year marriage (to Nina Wilcox) and worked on his first novel, On a Darkling Plain (Putnam, 1956), while he was a copy boy at The New York Times. He completed his second novel, The Losers (1958), as he traveled about Europe. While living on the island of Ibiza, he met an Englishwoman, Claire Lydon, and they married in 1958, moving to California. She was killed in Big Sur in an automobile accident.

On a Darkling Plain and The Losers were not financially successful but received excellent reviews. On a Darkling Plain was sometimes compared with another novel set at Cornell, Charles Thompson's Halfway Down the Stairs (1957). John O. Lyons, in an addendum to his 1962 survey "The College Novel in America: 1962-1974" (Critique, 1974), saw a tendency toward pranks and put-ons in Irving's early work (a critical analysis Irving dismissed as "nonsense"):

Richard Farina's Been Down So Long It Looks Like Up to Me (1966) continues the iconoclastic Cornell Bildungsroman of the fifties by Clifford Irving, On a Darkling Plain (1956); Charles Thompson, Halfway Down the Stairs (1957); and Robert Gutwillig, After Long Silence (1958). The oscillation between Weltschmerz and pranks in these novels was undoubtedly an influence on "The Whole Sick Crew" of Pynchon's V.

Irving's third novel, The Valley, is a mythic Western, published by McGraw-Hill in 1960. In 1962, Irving moved back to Ibiza with his third wife, English model Fay Brooke, and their newborn son, Josh. In 1967, he married Swiss/German artist Edith Sommer, and they had two sons, Nedsky and Barnaby. On Ibiza he was friendly with art forger Elmyr de Hory and was asked by De Hory to write his biography, Fake! (1969). Irving and de Hory are both featured in Orson Welles's documentary F for Fake (1974).

By 1958, Howard Hughes had become a recluse who hated any kind of public scrutiny. Whenever he found out that someone was writing an unauthorized biography about him, he bought the writer off. By the 1960s, he even refused to appear in court. According to various rumors, he was either terminally ill, mentally unstable, or even dead and replaced by an impersonator.

In 1970, in Spain, Irving met with an author and old friend, Richard Suskind, and spontaneously created the scheme to write Hughes's "autobiography." Irving and Suskind believed that because Hughes had completely withdrawn from public life, he would never want to draw attention to himself by denouncing the book or filing a lawsuit for slander. Suskind would do most of the necessary research in news archives. Irving started by forging letters in Hughes's own hand, imitating authentic letters he had seen displayed in Newsweek magazine.

Irving contacted his publisher, McGraw-Hill, and claimed that he had corresponded with Hughes because of his book about de Hory and that Hughes had expressed interest in letting him write his autobiography. The McGraw-Hill editors invited him to New York, where he showed them three forged letters, one of which claimed that Hughes wished to have his biography written but that he wanted the project to remain secret for the time being. The autobiography would be based on interviews Hughes was willing to do with Irving.

McGraw-Hill agreed to the terms and wrote up contracts between Hughes, Irving and the company; Irving forged Hughes's signatures. McGraw-Hill paid an advance of $100,000, with an additional $400,000 that would go to Hughes. Irving later bargained the sum up to $765,000, with $100,000 going to Irving and the rest to Hughes. McGraw-Hill paid by check, which Irving had his wife deposit to a Swiss bank account.

Irving and Suskind researched all the available information about Hughes. To reinforce the public perception of Hughes as an eccentric recluse, Irving also created fake interviews that he claimed were conducted in remote locations all over the world, including one on a Mexican pyramid. In reality, Irving was meeting his mistress, Danish Baroness Nina van Pallandt, at these destinations.

Irving and Suskind also gained access to the private files of Time-Life, as well as a manuscript by James Phelan, who was ghostwriting memoirs of Noah Dietrich, former business manager to Hughes. Mutual acquaintance and Hollywood producer Stanley Meyer showed Irving a copy of the manuscript—without Phelan's consent—in the hope that he would be willing to rewrite it in a more publishable format. Irving hurriedly made a copy of it for his own purposes.

In the early winter of 1971, Irving delivered the manuscript to McGraw-Hill. He also included notes in Hughes's forged handwriting that an expert forensic document analyst declared genuine. Hughes experts at Time-Life were also convinced. McGraw-Hill announced its intention to publish the book in March, 1972.

Several representatives of Hughes's companies and other people who had known the businessman expressed their doubts about the forthcoming work's authenticity. Irving countered that Hughes had simply not told them about the book. Meanwhile, Frank McCulloch, known for years as the last journalist to interview Hughes, received an angry call from someone claiming to be Hughes himself. But when McCulloch read the Irving manuscript, he declared that it was indeed accurate. Mike Wallace interviewed Irving for a news broadcast. Wallace later said his camera crew told him Irving was not telling the truth. "They understood. I didn't. He got me."

McGraw-Hill and Life magazine, which had paid to publish excerpts of the book, continued to support Irving. Osborn Associates, a firm of handwriting experts, declared the writing samples were authentic. Irving had to submit to a lie-detector test, the results of which indicated inconsistencies but no outright lies. For weeks, there was no sign of Hughes.

On January 7, 1972, Hughes finally contacted the outside world. He arranged a telephone conference with seven journalists who had known him years before. It took place two days later; the journalists' end of the conversation was televised. Hughes denounced Irving, said that he had never even met him, and said that he was still living in the Bahamas. Irving claimed that the voice was probably a fake.

Hughes's lawyer, Chester Davis, filed suit against McGraw-Hill, Life, Clifford Irving and Dell Publications. Swiss authorities investigated a bank account in the name of H. R. Hughes, which had received $750,000. Edith Irving had opened it with the name Helga R. Hughes. When Swiss police visited the Irvings on Ibiza, they denied everything, although Clifford Irving tried to hint that he might have been dealing with an impostor. Then, James Phelan read an excerpt of the book and realized that a few of the facts had been taken from his book. Finally, the Swiss bank identified Edith Irving as the depositor of the funds, and the jig was up.

Eventually, the Irvings gave up and confessed on January 28, 1972. They and Suskind were indicted for fraud, appeared in court on March 13, and were found guilty on June 16. Despite the efforts of Irving's lawyers, Maurice Nessen and Philip Lorber, Irving was convicted and spent 17 months in prison at the federal correctional facility in Danbury, Connecticut and at the Allenwood Prison in Pennsylvania, where he stopped smoking and took up weightlifting. He voluntarily returned the $765,000 advance to his publishers. Suskind was sentenced to six months and served five.

Following his release, Irving continued to write books, including several bestsellers, notably Trial, Tom Mix and Pancho Villa, Final Argument and Daddy's Girl.

The fraudulent autobiography was published in a private edition in 1999 and has been out of print, but, in March 2008, John Blake Publishing, a British company, issued Howard Hughes: The Autobiography. All the events of the experience were described in detail in Irving's The Hoax, published by The Permanent Press in 1981 .

In July 2005, filming began in Puerto Rico and New York on The Hoax, starring Richard Gere as Irving, Alfred Molina as Suskind, and Marcia Gay Harden as Edith. On March 6, 2007, Hyperion reissued Clifford Irving's The Hoax in a movie tie-in edition. The film, directed by Lasse Hallström, opened on April 6, 2007, with a DVD release following on October 16. The majority of reviews were favorable.

Irving, however, decried the film as a distortion of the story and "a hoax about a hoax," citing the film's portrayals of himself, Suskind and Edith Irving as inaccurate and claiming that the film added events and scenes that did not occur in real life. As the author of the source book, Irving is credited as a writer for the film.