Before Neuromancer, Gibson had written several short stories for prominent science fiction periodicals – mostly noir countercultural narratives concerning low-life protagonists in near-future encounters with cyberspace. The themes he developed in this early short fiction, the Sprawl setting of "Burning Chrome" (1982), and the character of Molly Millions from "Johnny Mnemonic" (1981) laid the foundations for the novel. John Carpenter's Escape from New York (1981) influenced the novel; Gibson was "intrigued by the exchange in one of the opening scenes where the Warden says to Snake 'You flew the Gulfire over Leningrad, didn't you?' [sic] It turns out to be just a throwaway line, but for a moment it worked like the best SF, where a casual reference can imply a lot." The novel's street and computer slang dialogue derives from the vocabulary of subcultures, particularly "1969 Toronto dope dealer's slang, or biker talk". Gibson heard the term "flatlining" in a bar around twenty years before writing Neuromancer and it stuck with him. Author Robert Stone, a "master of a certain kind of paranoid fiction", was a primary influence on the novel. The term "Screaming Fist" was taken from the song of the same name by Toronto punk rock band The Viletones.
Neuromancer was commissioned by Terry Carr for the second series of Ace Science Fiction Specials, which was intended to exclusively feature debut novels. Given a year to complete the work, Gibson undertook the actual writing out of "blind animal panic" at the obligation to write an entire novel – a feat which he felt he was "four or five years away from". After viewing the first 20 minutes of landmark cyberpunk film Blade Runner (1982), which was released when Gibson had written a third of the novel, he "figured [Neuromancer] was sunk, done for. Everyone would assume I’d copped my visual texture from this astonishingly fine-looking film." He re-wrote the first two-thirds of the book 12 times, feared losing the reader's attention and was convinced that he would be "permanently shamed" following its publication; yet what resulted was seen as a major imaginative leap forward for a first-time novelist. He added the final sentence of the novel, "He never saw Molly again", at the last minute in a deliberate attempt to prevent himself from ever writing a sequel, but ended up doing precisely that with Count Zero (1986), a character-focused work set in the Sprawl alluded to in its predecessor.