Bradbury was born in Waukegan, Illinois, to a Swedish immigrant mother and a father who was a power and telephone lineman. His paternal grandfather and great-grandfather were newspaper publishers. He is also somewhat distantly related to the American Spalding family, owners of the famous Spalding sports equipment company. His central character Douglas Spaulding, from the novel Dandelion Wine, was reportedly drawn from this heritage. He is also reputedly related to the American Shakespeare scholar Douglas Spaulding.

Bradbury was a reader and writer throughout his youth, spending much time in the Carnegie library in Waukegan, Illinois. He used this library as a setting for much of his novel Something Wicked This Way Comes, and depicted Waukegan as "Green Town" in some of his other semi-autobiographical novels...Dandelion Wine, Farewell Summer...as well as in many of his short stories.

He attributes his lifelong habit of writing every day to an incident in 1932 when a carnival entertainer, Mr. Electrico, touched him on the nose with an electrified sword, made his hair stand on end, and shouted, "Live forever!" It was from then that Bradbury wanted to live forever and decided on his career as an author in order to do what he was told: live forever. It was at that age that Bradbury first started to do magic. Magic was his first great love. If he had not discovered writing, he would have become a magician.

The Bradbury family lived in Tucson, Arizona, in 1926—27 and 1932—33 as his father pursued employment, each time returning to Waukegan, but eventually settled in Los Angeles in 1934, when Ray was thirteen.

Bradbury graduated from Los Angeles High School in 1938 but did not attend college. Instead, he sold newspapers at the corner of South Norton Avenue and Olympic Boulevard. In regard to his education, Bradbury said:

"Libraries raised me. I don’t believe in colleges and universities. I believe in libraries because most students don’t have any money. When I graduated from high school, it was during the Depression and we had no money. I couldn’t go to college, so I went to the library three days a week for 10 years."

It was in UCLA's Powell Library, in a study room with typewriters for rent, in which Bradbury wrote his classic story of a book-burning future, "Fahrenheit 451."

Having been influenced by science fiction heroes like Flash Gordon and Buck Rogers, Bradbury began to publish science fiction stories in fanzines in 1938. Bradbury was invited by Forrest J Ackerman to attend the now legendary Los Angeles Science Fiction Society, which at the time met at Clifton’s Cafeteria in downtown Los Angeles. This was where he met the writers Robert A. Heinlein, Emil Petaja, Fredric Brown, Henry Kuttner, Leigh Brackett, and Jack Williamson. His first published story was "Hollerbochen's Dilemma", which appeared in the fanzine Imagination! in January, 1938. Launching his own fanzine in 1939, titled Futuria Fantasia, he wrote most of its four issues, each limited to under 100 copies. Between 1940 and 1947, he was a contributor to Rob Wagner's film magazine, Script.

Bradbury's first paid piece, "Pendulum", written with Henry Hasse, was published in the pulp magazine Super Science Stories in November 1941, for which he earned $15. He became a full-time writer by the end of 1942. His first collection of short stories, Dark Carnival, was published in 1947 by Arkham House, a small press in Sauk City, Wis., owned by writer August Derleth.

A chance encounter in a Los Angeles bookstore with the British expatriate writer Christopher Isherwood gave Bradbury the opportunity to put The Martian Chronicles into the hands of a respected critic. Isherwood's glowing review followed.

Although he is often described as a science fiction writer, Bradbury does not box himself into a particular narrative categorization:

First of all, I don't write science fiction. I've only done one science fiction book and that's Fahrenheit 451, based on reality. Science fiction is a depiction of the real. Fantasy is a depiction of the unreal. So Martian Chronicles is not science fiction, it's fantasy. It couldn't happen, you see? That's the reason it's going to be around a long time...because it's a Greek myth, and myths have staying power.

On another occasion, Bradbury observed that the novel touches on the alienation of people by media:

Besides his fiction work, Bradbury has written many short essays on the arts and culture, attracting the attention of critics in this field. Bradbury was a consultant for the American Pavilion at the 1964 New York World's Fair and the original exhibit housed in Epcot's Spaceship Earth geosphere at Walt Disney World.

Ray Bradbury married Marguerite McClure (1922—2003) in 1947, and they had four daughters. To date, Bradbury has never obtained a driver's license.

Bradbury was a close friend of Charles Addams and Addams illustrated the first of Bradbury's stories about the Elliotts, a family that would resemble Addams' own Addams Family placed in rural Illinois. Bradbury's first story about them was "Homecoming," published in the 1946 Halloween issue of Mademoiselle, with Addams illustrations. He and Addams planned a larger collaborative work that would tell the family's complete history, but it never materialized and according to a 2001 interview they went their separate ways. In October 2001, Bradbury published all the Family stories he had written in one book with a connecting narrative, From the Dust Returned, featuring a wraparound Addams cover of the original 'Homecoming' illustration.

Critical opinion of Bradbury's work is sharply divided. In his review of The Martian Chronicles, Christopher Isherwood wrote:

... the sheer lift and power of a truly original imagination exhilarates... His is a very great and unusual talent.

At the other extreme, science fiction author and critic Damon Knight wrote:

Although [Bradbury] has a large following among science fiction readers, there is at least an equally large contingent of people who cannot stomach his work at all ... His imagination is mediocre; he borrows nearly all his backgrounds and props, and distorts them badly; wherever he is required to invent anything -- a planet, a Martian, a machine -- the image is flat and unconvincing.

From 1951 to 1954, 27 of Bradbury's stories were adapted by Al Feldstein for EC Comics, and 16 of these were collected in the paperbacks, The Autumn People (1965) and Tomorrow Midnight (1966), both published by Ballantine Books with cover illustrations by Frank Frazetta.

Also in the early 1950s, adaptations of Bradbury's stories were televised on a variety of anthology shows, including Tales of Tomorrow, Lights Out, Out There, Suspense, CBS Television Workshop, Jane Wyman's Fireside Theatre, Star Tonight, Windows and Alfred Hitchcock Presents. "The Merry-Go-Round," a half-hour film adaptation of Bradbury's "The Black Ferris," praised by Variety, was shown on Starlight Summer Theater in 1954 and NBC's Sneak Preview in 1956. During this same period, several were also adapted for radio drama, in particular on the science fiction anthologies Dimension X and its successor X Minus One.

Producer William Alland first brought Bradbury to movie theaters in 1953 with It Came from Outer Space, a Harry Essex screenplay developed from Bradbury's screen treatment "Atomic Monster". Three weeks later came the release of Eugène Lourié's The Beast from 20,000 Fathoms (1953), which featured one scene based on Bradbury's "The Fog Horn", about a sea monster mistaking the sound of a fog horn for the mating cry of a female. Bradbury's close friend Ray Harryhausen produced the stop-motion animation of the creature. Bradbury would later return the favor by writing a short story, "Tyrannosaurus Rex", about a stop-motion animator who strongly resembled Harryhausen. Over the next 50 years, more than 35 features, shorts, and TV movies were based on Bradbury's stories or screenplays.

Additionally, Bradbury was hired in 1953 by director John Huston to work on the screenplay for the 1956 film Moby Dick, which was faithfully based on the novel by Herman Melville and starred Gregory Peck as Captain Ahab, Richard Basehart as Ishmael, and Orson Welles as Father Mapple. A significant result of the film was Bradbury's book Green Shadows, White Whale, a semi-fictionalized account of the making of the film, including Bradbury's dealings with Huston and his time in Ireland, where exterior scenes that were set in New Bedford, Massachusetts, were filmed.

Bradbury's short story I Sing the Body Electric (from the book of the same name) was adapted for the 100th episode of the American TV series The Twilight Zone. The episode was first aired on 18 May 1962.

Oskar Werner and Julie Christie starred in Fahrenheit 451 (1966), an adaptation of Bradbury's novel directed by François Truffaut.

In 1969, The Illustrated Man was brought to the big screen, starring Oscar winner Rod Steiger, Claire Bloom and Robert Drivas. Containing the prologue and three short stories from the book, the film received mediocre reviews.

The Martian Chronicles became a three-part TV miniseries starring Rock Hudson which was first broadcast by NBC in 1980. Bradbury found the miniseries "just boring".

The 1983 horror film Something Wicked This Way Comes, starring Jason Robards and Jonathan Pryce, is based on the Bradbury novel of the same name.

In 1984, Michael McDonough of Brigham Young University produced "Bradbury 13," a series of 13 audio adaptations of famous Ray Bradbury stories, in conjunction with National Public Radio. The full-cast dramatizations featured adaptations of "The Man," "The Ravine," "Night Call, Collect," "The Veldt", "Kaleidoscope," "There Was an Old Woman," "Here There Be Tygers," "Dark They Were, and Golden-Eyed", "The Wind," "The Fox and the Forest," "The Happiness Machine," "The Screaming Woman" and "A Sound of Thunder". Voiceover actor Paul Frees provided narration, while Bradbury himself was responsible for the opening voiceover; Greg Hansen and Roger Hoffman scored the episodes. The series won a Peabody Award as well as two Gold Cindy awards and was released on CD on May 1, 2010.

From 1985 to 1992 Bradbury hosted a syndicated anthology television series, The Ray Bradbury Theater, for which he adapted 65 of his stories. Each episode would begin with a shot of Bradbury in his office, gazing over mementoes of his life, which he states (in narrative) are used to spark ideas for stories. During the first two seasons, Bradbury also provided additional voiceover narration specific to the featured story and appeared on screen.

Five episodes of the USSR science fiction TV series This Fantastic World adapted Ray Bradbury's stories I Sing The Body Electric, Fahrenheit 451, A Piece of Wood, To the Chicago Abyss, and Forever and the Earth. A Soviet adaptation of "The Veldt" was filmed in 1987.

The 1998 film The Wonderful Ice Cream Suit, released by Touchstone Pictures, was written by Ray Bradbury. It was based on his story "The Magic White Suit" originally published in The Saturday Evening Post in 1957. The story had also previously been adapted as a play, a musical, and a 1958 television version.

In 2002, Bradbury's own Pandemonium Theatre Company production of Fahrenheit 451 at Burbank's Falcon Theatre combined live acting with projected digital animation by the Pixel Pups. In 1984 Telarium released a video game for Commodore 64 based on Fahrenheit 451. Bradbury and director Charles Rome Smith co-founded Pandemonium in 1964, staging the New York production of The World of Ray Bradbury (1964), adaptations of "The Pedestrian", "The Veldt", and "To the Chicago Abyss."

In 2005, the film A Sound of Thunder was released, loosely based upon the short story of the same name. Short film adaptations of A Piece of Wood and The Small Assassin were released in 2005 and 2007 respectively.

In 2005 it was reported that Bradbury was upset with filmmaker Michael Moore for using the title Fahrenheit 9/11, which is an allusion to Bradbury's Fahrenheit 451, for his documentary about the George W. Bush administration. Bradbury expressed displeasure with Moore's use of the title but stated that his resentment was not politically motivated. Bradbury asserts that he does not want any of the money made by the movie, nor does he believe that he deserves it. He pressured Moore to change the name, but to no avail. Moore called Bradbury two weeks before the film's release to apologize, saying that the film's marketing had been set in motion a long time ago and it was too late to change the title.

In 2008, the film Ray Bradbury's Chrysalis was produced by Roger Lay Jr for Urban Archipelago Films, based upon the short story of the same name. The film went on to win the best feature award at the International Horror and Sci-Fi Film Festival in Phoenix. The film has been picked up for international distribution by Arsenal Pictures and for domestic distribution by Lightning Entertainment.

Bradbury's works and approach to writing are documented in Terry Sanders' film Ray Bradbury: Story of a Writer (1963).