Plimpton was born in New York City on March 18, 1927, and spent his childhood there, attending St. Bernard’s School and growing up in an apartment duplex on Manhattan’s Upper East Side located at 1165 Fifth Avenue. During the summers, he lived in the hamlet of West Hills, Huntington, Suffolk County on Long Island.

Plimpton attended St. Bernard’s School, Phillips Exeter Academy (from which he was expelled just shy of graduation), and Mainland High School, where he received his high school diploma before entering Harvard College in July 1944. He wrote for the Harvard Lampoon, was a member of the Hasty Pudding Club, Pi Eta, the Signet Society, and the Porcellian Club. He majored in English. Plimpton entered Harvard as a member of the Class of 1948, but did not graduate until 1950 due to intervening military service. He was also an accomplished birdwatcher.

In 1953, Plimpton joined the influential literary journal The Paris Review, founded by Peter Matthiessen, Thomas H. Guinzburg, and Harold L. “Doc” Humes, becoming its first editor in chief. This periodical has carried great weight in the literary world, but has never been financially strong; for its first half-century, it was allegedly largely financed by its publishers and by Plimpton. Peter Matthiessen took the magazine over from Humes and ousted him as editor, replacing him with Plimpton, using it as his cover for his CIA activities. Jean Stein became his co-editor. Plimpton was associated with the literary magazine in Paris, Merlin, which folded because the State Department withdrew its support. Future Poet Laureate Donald Hall, who had met Plimpton at Exeter, was Poetry Editor. One of the magazine’s most notable discoveries was author and screenplay writer Terry Southern, who was living in Paris at the time and formed a lifelong friendship with Plimpton, along with writer Alexander Trocchi and future classical and jazz pioneer David Amram.

Outside the literary world, Plimpton was famous for competing in professional sporting events and then recording the experience from the point of view of an amateur. In 1958, prior to a post-season exhibition game at Yankee Stadium between teams managed by Willie Mays (National League) and Mickey Mantle (American League), Plimpton pitched against the National League. His experience was captured in the book Out of My League. (He intended to face both line-ups, but tired badly and was relieved by Ralph Houk.) Plimpton sparred for three rounds with boxing greats Archie Moore and Sugar Ray Robinson while on assignment for Sports Illustrated.

In 1963, Plimpton attended preseason training with the Detroit Lions of the National Football League as a backup quarterback, and he ran a few plays in an intrasquad scrimmage. These events were recalled in his best-known book Paper Lion, which was later adapted into a 1968 feature film starring Alan Alda. Plimpton revisited pro football in 1971, this time joining the Baltimore Colts and seeing action in an exhibition game against his previous team, the Lions. These experiences served as the basis of another football book, Mad Ducks and Bears, although much of the book dealt with the off-field escapades and observations of football friends Alex Karras (“Mad Duck”) and John Gordy (“Bear”). Another sports book, Open Net, saw him train as an ice hockey goalie with the Boston Bruins, even playing part of a National Hockey League preseason game.

Plimpton was married twice. His first wife, whom he married in 1968 and divorced in 1988, was Freddy Medora Espy, a photographer’s assistant. She was the daughter of writers Willard R. Espy and Hilda S. Cole, who had, earlier in her career, been a publicity agent for Kate Smith and Fred Waring. They had two children: Medora Ames Plimpton and Taylor Ames Plimpton, who has published a memoir entitled Notes from the Night: A Life After Dark.

At Harvard, Plimpton was a classmate and close personal friend of Robert F. Kennedy. Plimpton, along with former decathlete Rafer Johnson and American football star Rosey Grier, was credited with helping wrestle Sirhan Sirhan to the floor when Kennedy was assassinated following his victory in the 1968 California Democratic primary at the former Ambassador Hotel in Los Angeles, California. Kennedy died the next day at Good Samaritan Hospital.

In 1975, in Bellport, Long Island, Plimpton, with Fireworks by Grucci attempted to break the record for the world’s largest firework. His firework, a Roman candle named “Fat Man”, weighed 720 pounds (330 kg) and was expected to rise to 1,000 feet (300 m) or more and deliver a wide starburst. When lit, the firework remained on the ground and exploded, blasting a crater 35 feet (11 m) wide and 10 feet (3.0 m) deep. A later attempt, fired at Cape Canaveral, rose approximately 50 feet (15 m) into the air and broke 700 windows in Titusville, Florida.

With Felix Grucci, Plimpton competed in the 16th International Fireworks Festival in 1979 in Monte Carlo. After several problems with transporting and preparing the fireworks, Plimpton and Grucci became the first competitors from the United States to win the event. Plimpton later wrote the book Fireworks, and hosted an A&E Home Video with the same name featuring his many fireworks adventures with the Gruccis of New York in Monte Carlo and for the 1983 Brooklyn Bridge Centennial.

A friend of the New England Sedgwick family, Plimpton edited Edie: An American Biography with Jean Stein in 1982. He also appeared in a brief interview about Edie Sedgwick in the DVD extra for the film Ciao! Manhattan. He appeared in the PBS American Masters documentary on Andy Warhol. Plimpton also appeared in the closing credits of the 2006 film Factory Girl. Between 2000 and 2003, Plimpton wrote the libretto to a new opera, Animal Tales, commissioned by Family Opera Initiative, with music by Kitty Brazelton directed by Grethe Barrett Holby. He wrote, “I suppose in a mild way there is a lesson to be learned for the young, or the young at heart – the gumption to get out and try one’s wings”.

Plimpton appeared in the 1989 documentary The Tightrope Dancer which featured the life and the work of the artist Vali Myers. He was one of her original supporters and had published an article about her work in The Paris Review. He also appeared in the 1996 documentary When We Were Kings about the “Rumble in the Jungle” 1974 Ali-Foreman Championship fight opposite Norman Mailer crediting Muhammad Ali as a poet who composed the world’s shortest poem: “Me? Whee!!”

In 1992, Plimpton married Sarah Whitehead Dudley, a graduate of Columbia University and a freelance writer. She is the daughter of James Chittenden Dudley, a managing partner of Manhattan-based investment firm Dudley and Company, and geologist Elisabeth Claypool. The Dudleys established the 36-acre (15 ha) Highstead Arboretum in Redding, Connecticut. Plimpton and Dudley were the parents of twin daughters Laura Dudley Plimpton and Olivia Hartley Plimpton.

In 1994 Plimpton appeared several times in the Ken Burns series Baseball, in which he shared some personal baseball experiences as well as other memorable events throughout the history of baseball.

Plimpton died on September 25, 2003, in his New York City apartment from a heart attack later determined to have been caused by a catecholamine surge. He was 76.

In 2006, the musician Jonathan Coulton wrote the song entitled “A Talk with George”, a part of his ‘Thing a Week’ series, in tribute to Plimpton’s many adventures and approach to life.

An oral biography titled George, Being George was edited by Nelson W. Aldrich Jr., and released on October 21, 2008. The book offers memories of Plimpton from among other writers, such as Norman Mailer, William Styron, Gay Talese and Gore Vidal, and was written with the cooperation of both his ex-wife and his widow.

Researcher and writer Samuel Arbesman filed with NASA to name an asteroid after Plimpton; NASA issued the certificate 7932 Plimpton in 2009. His final interview appeared in The New York Sports Express of Oct. 2, 2003 by journalist Dave Hollander.

Plimpton was a member of the cast of the A&E TV series A Nero Wolfe Mystery (2001–02). In 2013, the documentary Plimpton! Starring George Plimpton as Himself, directed by Tom Bean and Luke Poling, was released. The film used archival audio and video of Plimpton lecturing and reading to create a posthumous narration.