King has received many awards, including several Bram Stoker Awards, Locus Awards, and, in 2003, the National Book Foundation awarded him the Medal for Distinguished Contribution to American Letters.

King and his wife, Tabitha, have three children, Naomi, Joe and Owen. Tabitha, Joe and Owen are also published writers.

King's father, Donald Edwin King, who was born ca. 1913 in Peru, Indiana, was a merchant seaman; his mother, Nellie Ruth (née Pillsbury) (March 13, 1913 - December 28, 1973) was born in Scarborough, Maine. They got married July 23, 1939 in Cumberland County, Maine.

Stephen King was born September 21, 1947 in Portland, Maine. When King was two years old, his father left the family under the pretense of "going to buy a pack of cigarettes," leaving his mother to raise King and his adopted older brother David by herself, sometimes under great financial strain. The family moved to De Pere, Wisconsin; Fort Wayne, Indiana; and Stratford, Connecticut. When King was eleven years old, the family returned to Durham, Maine, where Ruth King cared for her parents until their deaths. She then became a caregiver in a local residential facility for the mentally challenged.

As a child, King apparently witnessed one of his friends being struck and killed by a train, though he has no memory of the event. His family told him that after leaving home to play with the boy, King returned, speechless and seemingly in shock. Only later did the family learn of the friend's death. Some commentators have suggested that this event may have psychologically inspired some of King's darker works, but King himself has dismissed the idea.

King's primary inspiration for writing horror fiction was related in detail in his 1981 non-fiction Danse Macabre, in a chapter titled "An Annoying Autobiographical Pause". King makes a comparison of his uncle successfully dowsing for water using the bough of an apple branch with the sudden realization of what he wanted to do for a living. While browsing through an attic with his elder brother, King uncovered a paperback version of an H. P. Lovecraft collection of short stories that had belonged to his father. The cover art—an illustration of a yellow-green Demon hiding within the recesses of a Hellish cavern beneath a tombstone—was, he writes,

"The moment of my life when the dowsing rod suddenly went down hard... as far as I was concerned, I was on my way."

King attended Durham Elementary School and graduated from Lisbon Falls High School in Lisbon Falls, Maine. He displayed an early interest in horror as an avid reader of EC's horror comics, including Tales from the Crypt (he later paid tribute to the comics in his screenplay for Creepshow). He began writing for fun while still in school, contributing articles to Dave's Rag, the newspaper that his brother published with a mimeograph machine and later began selling stories to his friends which were based on movies he had seen (though when discovered by his teachers, he was forced to return the profits). The first of his stories to be independently published was "I Was a Teenage Grave Robber", serialized over three published and one unpublished issue of a fanzine, Comics Review, in 1965. That story was published the following year in a revised form as "In a Half-World of Terror" in another fanzine, Stories of Suspense, edited by Marv Wolfman.

From 1966, King studied English at the University of Maine, where he graduated in 1970, the year in which his first daughter, Naomi Rachel, was born, with a Bachelor of Science in English. He wrote a column for the student newspaper, The Maine Campus, titled "Steve King's Garbage Truck", took part in a writing workshop organized by Burton Hatlen, and took odd jobs to pay for his studies, including one at an industrial laundry. He sold his first professional short story, "The Glass Floor", to Startling Mystery Stories in 1967. The Fogler Library at UMaine now holds many of King's papers.

After leaving the university, King earned a certificate to teach high school but, being unable to find a teaching post immediately, initially supplemented his laboring wage by selling short stories to men's magazines such as Cavalier. Many of these early stories have been published in the collection Night Shift. In 1971, King married Tabitha Spruce, a fellow student at the University of Maine whom he had met at the University's Fogler Library after one of Professor Hatlen's workshops. That fall, King was hired as a teacher at Hampden Academy in Hampden, Maine. He continued to contribute short stories to magazines and worked on ideas for novels. It was during this time that King developed a drinking problem, which stayed with him for more than a decade.