George Raymond Martin (he later adopted the confirmation name Richard at 13 years old) was born on September 20, 1948, in Bayonne, New Jersey, the son of longshoreman Raymond Collins Martin and his wife Margaret Brady Martin. He has two younger sisters, Darleen and Janet. His father was of half Italian descent, while his mother was of half Irish ancestry. He also has French, English, Welsh and German roots.

The family first lived in a house on Broadway, belonging to Martin's great-grandmother. In 1953, they moved to a federal housing project near the Bayonne docks. During Martin's childhood, his world consisted predominantly of "First Street to Fifth Street", between his grade school and his home; this limited world made him want to travel and experience other places, but the only way of doing so was through his imagination, so he became a voracious reader. The young Martin began writing and selling Monster stories for pennies to other neighborhood children, dramatic readings included. He also wrote stories about a mythical kingdom populated by his pet turtles; the turtles died frequently in their toy castle, so he finally decided they were killing each other off in "sinister plots".

Martin attended Mary Jane Donohoe School and then later Marist High School. While there he became an avid comic-book fan, developing a strong interest in the superheroes being published by Marvel Comics. A letter Martin wrote to the Editor of Fantastic Four was printed in issue No. 20 (Nov 1963); it was the first of many sent, e.g., FF #32, #34, and others. Fans who read his letters then wrote him letters in turn, and through such contacts, Martin joined the fledgling comics fandom of the era, writing fiction for various fanzines; he was the first to register for an early comic book convention held in New York in 1964. In 1965, Martin won comic fandom's Alley Award for Best fan fiction for his prose superhero story "Powerman vs. The Blue Barrier".

In the early 1970s, Martin was in a relationship with fellow science-fiction/fantasy author Lisa Tuttle, with whom he co-wrote Windhaven.

The short stories he was able to sell in his early 20s gave him some profit, but not enough to pay his bills, which prevented him from becoming the full-time Writer he wanted to be. The need for a day job occurred simultaneously with the American chess craze which followed Bobby Fischer's victory in the 1972 world chess championship. Martin's own chess skills and experience allowed him to be hired as a tournament Director for the Continental Chess Association that ran chess tournaments in the weekends. This gave him a sufficient income, and because the tournaments only ran on Saturdays and Sundays, it allowed him to work as a Writer five days a week from 1973 to 1976. When the chess bubble finally burst and no longer provided an income, he had become much better established as a Writer.

In turn, Guthridge helped Martin find a job at Clarke University (then Clarke College). Martin "wasn't making enough money to stay alive", from writing and the chess tournaments, says Guthridge. From 1976 to 1978, Martin was an English and journalism instructor at Clarke, and he became Writer In Residence at the college from 1978 to 1979.

Martin is a member of the Science Fiction and Fantasy Writers of America (SFWA), and he became the organization's Southwest Regional Director from 1977 to 1979; he served as its vice-president from 1996 to 1998. In 1976, for Kansas City's MidAmeriCon, the 34th World Science Fiction Convention (Worldcon), Martin and his friend and fellow writer-editor Gardner Dozois conceived of and organized the first Hugo Losers' Party for the benefit of all past and present Hugo-losing Writers on the evening following the convention's Hugo Awards ceremony. Martin was nominated for two Hugos that year but lost both awards, for the novelette "...and Seven Times Never Kill Man" and the novella The Storms of Windhaven, co-written with Lisa Tuttle. The Hugo Losers' Party became an annual Worldcon event thereafter, and its formal title later changed.

Martin is known for his regular attendance through the decades at science fiction conventions and comics conventions, and his accessibility to fans. In the early 1980s, critic and Writer Thomas Disch identified Martin as a member of the "Labor Day Group", Writers who regularly congregated at the annual Worldcon, usually held on or around the Labor Day weekend. Since the early 1970s, he has also attended regional science fiction conventions, and since 1986 Martin has participated annually in Albuquerque's smaller regional convention Bubonicon, near his New Mexico home. He was the Guest of Honor at the 61st World Science Fiction Convention in Toronto, held in 2003.

In 1982, Martin published a vampire novel titled Fevre Dream set in the 19th century on the Mississippi River. Unlike traditional vampire novels, in Fevre Dream vampires are not supernatural creatures, but are rather a different species related to humans created by evolution with superhuman powers. Critic Don D'Amassa has praised Fevre Dream for its strong 19th century atmosphere and wrote: "This is without question one of the greatest vampire novels of all time". Martin followed up Fevre Dream with another horror novel, The Armageddon Rag. The unexpected commercial failure of The Armageddon Rag (1983), "essentially destroyed my career as a Novelist at the time", he recalled. In 1984 the new Editor of Baen Books, Betsy Mitchell, called Martin to ask him if he had considered doing a collection of Haviland Tuf adventures. Martin, which had several favorite series characters like Solomon Kane, Elric, Nicholas van Rijn and Magnus Ridolph, had made an attempt to create such a character on his own in the 1970s with his Tuf stories. He was interested, but was too occupied with the writing of his next book, the never completed novel Black and White and Red All Over, which occupied most of his writing time the same year. But after the failure of The Armageddon Rag, all editors rejected his upcoming novel, and being desperate for money, he accepted Mitchell's offer and wrote some more Tuf stories which were collected in Tuf Voyaging, which sold well enough for Mitchell to suggest a sequel. Martin was willing and agreed to do it, but before he got started he got an offer from Hollywood, where Producer Philip DeGuere Jr. wanted to adapt The Armageddon Rag into a movie. The movie never happened, but they stayed in touch, and when he became the Producer for the revival of the Twilight Zone, Martin was offered a job as a Writer. Working for television paid a lot better than writing literature, so he decided to move to Hollywood to seek a new career. At first he worked a staff Writer for the show, and then as an Executive Story Consultant. After the CBS series was cancelled, Martin migrated over to the already-underway satirical science fiction series Max Headroom. He worked on scripts and created the show's "Ped Xing" character. However, before his scripts could go into production, the ABC show was cancelled in the middle of its second season. Martin was then hired as a writer-producer on the new dramatic fantasy series Beauty and the Beast; in 1989, he became the show's co-supervising Producer and wrote 14 of its episodes.

In 1987, Martin published a collection of short horror stories in Portraits of His Children. During this same period, Martin continued working in print media as a book-series Editor, this time overseeing the development of the multi-author Wild Cards book series, which takes place in a shared universe in which a small slice of post–World War II humanity gains superpowers after the release of an alien-engineered virus; new titles are still being published in the ongoing series from Tor Books. In Second Person, Martin "gives a personal account of the close-knit role-playing game (RPG) culture that gave rise to his Wild Cards shared-world anthologies". An important element in the creation of the multiple author series was a campaign of Chaosium's role-playing game Superworld (1983) that Martin ran in Albuquerque. Admitting he became completely obsessed with the game, he stopped writing literature for most of 1983, which he refers to as his "lost year", but his shrinking bank accounts made him realize he had to come up with something, and got the idea that perhaps the stories and characters created in Superworld could somehow become profitable. Martin's own contributions to Wild Cards have included Thomas Tudbury, "The Great and Powerful Turtle", a powerful psychokinetic whose flying "shell" consisted of an armored VW Beetle. As of June 2011, 21 Wild Cards volumes had been published in the series; earlier that same year, Martin signed the contract for the 22nd volume, Low Ball (2014), published by Tor Books. In early 2012, Martin signed another Tor contract for the 23rd Wild Cards volume, High Stakes, which was released in August 2016.

In 1991, Martin briefly returned to writing novels. He had grown frustrated that his TV pilots and screenplays were not getting made and that TV-related production limitations like budgets and episode lengths were forcing him to cut characters and trim battle scenes. This pushed Martin back towards writing books, where he did not have to worry about compromising the size of his imagination. Admiring the works of J. R. R. Tolkien in his childhood, he wanted to write an epic fantasy, though he did not have any specific ideas.

He has also written at least one piece of political-military fiction, "Night of the Vampyres", collected in Harry Turtledove's anthology The Best Military Science Fiction of the 20th Century (2001).

Martin has been criticized by some of his readers for the long periods between books in the Ice and Fire series, notably the six-year gap between the fourth volume, A Feast for Crows (2005), and the fifth volume, A Dance with Dragons (2011). The previous year, in 2010, Martin had responded to fan criticisms by saying he was unwilling to write only his Ice and Fire series, noting that working on other prose and compiling and editing different book projects have always been part of his working process. Writer Neil Gaiman famously wrote on his blog in 2009 to a critic of Martin's pace, "George R. R. Martin is not your bitch." Gaiman later went on to state that Writers are not machines and that they have every right to work on other projects if they want to.

While attending an East Coast science fiction convention he met his first wife, Gale Burnick; they were married in 1975, but the marriage ended in divorce, without issue, in 1979. On February 15, 2011, Martin married his longtime partner Parris McBride during a small ceremony at their Santa Fe home. On August 19, 2011, they held a larger wedding ceremony and reception at Renovation, the 69th World Science Fiction Convention, in Reno, Nevada.

The second season, based on the second A Song of Ice and Fire novel A Clash of Kings, began airing on HBO in the US on April 1, 2012. The second season was nominated for 12 Emmy Awards, including another Supporting Actor nomination for Dinklage. It went on to win six of those Emmys in the Technical Arts categories, which were awarded the week before the regular televised 2012 awards show. The second-season episode "Blackwater", written by George R.R. Martin, was nominated the following year for the 2013 Hugo Award in the Best Dramatic Presentation, Short Form category; that episode went on to win the Hugo Award at LoneStarCon 3, the 71st World Science Fiction Convention, in San Antonio, Texas. In addition to Martin, Showrunners Benioff and Weiss (who contributed several scenes to the final screenplay) and episode Director Neil Marshal (who expanded the scope of the episode on set) received Hugo statuettes.

He and his wife Parris are supporters of the Wild Spirit Wolf Sanctuary in New Mexico. In early 2013, he purchased Santa Fe's Jean Cocteau Cinema and Coffee House, which had been closed since 2006. He had the property completely restored, including both its original 35 mm capability to which was added digital projection and sound; the Cocteau officially reopened for Business on August 9, 2013. Martin has also supported Meow Wolf, an arts collective in Santa Fe, having pledged $2.7 million towards a new art-space in January 2015.

In the midst of pressure to pull the 2014 feature film The Interview from theatres, the Jean Cocteau Theatre in Santa Fe, New Mexico, which has been owned by Martin since 2013, decided to show the film. Theatre manager Jon Bowman told the Santa Fe New Mexican: "Martin feels strongly about the First Amendment and the idea of artists having the ability to speak their minds and not having to worry about being targets."

On November 20, 2015, writing on his LiveJournal blog, Martin advocated for allowing Syrian refugees into the United States. He supported Hillary Clinton in the 2016 United States presidential election, and criticized Donald Trump following her defeat in the election, commenting that Trump would "become the worst President in American history".

In December 2016, Martin was a key speaker at the Guadalajara International Book Fair 2016 in Mexico where the author provided hints about the next two books in the series A Song of Ice and Fire.

In 2017, Martin confirmed he will serve as an executive Producer of the HBO television series adaptation of the 2010 novel Who Fears Death by Nnedi Okorafor.

Martin actively contributes to his blog, Not a Blog; in April 2018 he moved his blog from Livejournal to his own webstie. He still does all his "writing on an old DOS machine running Wordstar 4.0".

HBO confirmed that season 8 has been ordered and that it would be the last of the series; it will be aired in 2019. In November 2016, President of Programming Casey Bloys indicated that he had had preliminary discussions about a prequel spinoff to the Game of Thrones series with Martin. In May 2017, HBO commissioned five screenwriters – Max Borenstein, Jane Goldman, Brian Helgeland, Carly Wray and Bryan Cogman – to develop individual spin-offs. All of the Writers are to be working individually with George R. R. Martin. According to Casey Bloys, Martin is co-writing two of the four announced scripts.