Merle Miller was born in Montour, Iowa; he grew up in Marshalltown, Iowa and attended the University of Iowa and the London School of Economics. During World War II, Miller served in the U.S. Army Air Corps as an editor of Yank. After the war he worked Time and Harper's magazines (1945-1949). His first novel was That Winter ( 1948). His other books are The Sure Thing (1949); Reunion (1954); A Gay and Melancholy Sound (1961); Only You, Dick Daring! (1964); The Warm Feeling (1968); What Happened (1972); A Secret Understanding (1961); On Being Different (1971); and Lyndon: An Oral Biography (1980).

In Only You, Dick Darling!, his scathing account of trying to make a show with CBS for the 1963-1964 television season, Merle Miller talks of how James T. Aubrey, Jr., the president of the CBS Television Network, would simply walk out of meetings without offering any substantive comments, good or bad. Miller was assured by other CBS executives that meant things were fine, but Miller learned later of efforts to force him out. A pilot for the show, Calhoun, to star Jackie Cooper and Barbara Stanwyck, was shot and put on the fall schedule, but never aired.

Miller died in 1986 in Danbury, Connecticut from complications following abdominal surgery.

In 1995 Miller's most famous book, Plain Speaking: An Oral Biography of Harry S Truman, became the focus of an intense controversy. That year Dr. Robert Ferrell, an historian who had published his own biography of Truman, asserted in an article for American Heritage magazine that Miller had fabricated many of the quotes in his book. In 1962, Miller had done a series of filmed interviews with former President Truman; his hope was to sell the interviews to a television network. When no network bought the rights, Miller printed the interviews in 1974 and turned them into the bestselling and influential Plain Speaking. In the book, Truman came across as a salty, colorful, and tart-tongued politician who said many "politically-incorrect" things. In Plain Speaking, Miller quoted Truman as referring to General Douglas MacArthur as a "dumb-son-of-a-bitch" and quoted Truman as asserting that Dwight Eisenhower, his successor in the Oval Office, tried to divorce his wife Mamie in order to marry Kay Summersby, his English chaffeur and secretary during World War II. In Miller's recounting, Truman claimed that General George C. Marshall wrote Eisenhower a letter threatening to ruin his career if he divorced his wife. According to Dr. Ferrell, however, Truman never actually said any of this, and he accused Miller of simply making up Truman's quotes to make his book more interesting and lively. Ferrell claimed that Miller's papers on file in the Truman presidential library include no references to a number of Truman's quotes in Plain Speaking, and in his opinion the quotes are most likely forgeries created by Miller, and are not real Truman quotes or statements. Ferrell also mentioned a letter written by Truman to Miller complaining about the "misstatements" contained in Miller's written account of their interviews, and threatening a lawsuit if Miller published his interviews with Truman. As Ferrell noted, Miller waited until nearly two years after Truman's death to publish Plain Speaking. Ferrell claimed that this was done to eliminate the possibility of a lawsuit or of Truman claiming that the quotes in the book were inaccurate or fiction.