The Maupassants were an old Lorraine family who had settled in Normandy in the middle of the 18th century. In 1846 his father had married a young lady of the well-to-do bourgeoisie, Laure Le Poittevin. With her brother Alfred, she had been the playmate of Gustave Flaubert, the son of a Rouen surgeon, who was destined to have a directing influence on her son's life. She was a woman of no common literary accomplishments, very fond of the classics, especially Shakespeare. Separated from her husband, she kept her two sons, Guy and his younger brother Hervé.

Until he was thirteen years old Guy lived with his mother at Étretat, in the Villa des Verguies, where between the sea and the luxuriant country, he grew very fond of nature and outdoor sports; he went fishing with the fishermen off the coast and spoke patois with the peasants. He was deeply devoted to his mother.

He first entered a seminary at Yvetot, but deliberately managed to have himself expelled. From his early religious education he retained a marked hostility to religion.
Then he was sent to the Rouen Lycée, where he proved a good scholar indulging in poetry and taking a prominent part in theatricals.

The Franco-Prussian War broke out soon after his graduation from college in 1870; he enlisted as a volunteer and fought gallantly. After the war, in 1871, he left Normandy and came to Paris where he spent ten years as a clerk in the Navy Department. During these ten tedious years his only recreation was canoeing on the Seine on Sundays and holidays.

Gustave Flaubert took him under his protection and acted as a kind of literary guardian to him, guiding his debut in journalism and literature. At Flaubert's home he met Émile Zola and the Russian novelist Ivan Turgenev, as well as many of the protagonists of the realist and naturalist schools. He wrote considerable verse and short plays.

In 1878 he was transferred to the Ministry of Public Instruction and became a contributing editor of several leading newspapers such as Le Figaro, Gil Blas, Le Gaulois and l'Echo de Paris. He devoted his spare time to writing novels and short stories. In 1880 he published his first masterpiece, "Boule de Suif", which met with an instant and tremendous success. Flaubert characterized it as "a masterpiece that will endure".

The decade from 1880 to 1891 was the most fertile period of Maupassant's life. Made famous by his first short story, he worked methodically and produced two or sometimes four volumes annually. He combined talent and practical business sense, which brought him affluence and wealth.

In 1881 he published his first volume of short stories under the title of La Maison Tellier; it reached its twelfth edition in two years; in 1883 he finished his first novel, Une Vie (translated into English as A Woman's Life), twenty-five thousand copies of which were sold in less than a year. In his novels, he concentrated all his observations scattered in his short stories. His second novel Bel-Ami, which came out in 1885, had thirty-seven printings in four months. His editor, Havard, commissioned him to write new masterpieces and, without the slightest effort, his pen produced works of style, description, conception, and penetration. At this time he wrote what many consider to be his greatest novel, Pierre et Jean.

With a natural aversion for society, he loved retirement, solitude, and meditation. He traveled extensively in Algeria, Italy, England, Brittany, Sicily, Auvergne, and from each voyage he brought back a new volume. He cruised on his private yacht "Bel-Ami", named after his earlier novel. This feverish life did not prevent him from making friends among the literary celebrities of his day: Alexandre Dumas, fils had a paternal affection for him; at Aix-les-Bains he met Taine and fell under the spell of the philosopher-historian.

Flaubert continued to act as his literary godfather. His friendship with the Goncourts was of short duration; his frank and practical nature reacted against the ambience of gossip, scandal, duplicity, and invidious criticism that the two brothers had created around them in the guise of an 18th-century style salon. He hated the human comedy, the social farce.

In his latter years he developed an exaggerated love for solitude, a predilection for self-preservation, and a constant fear of death and mania of persecution, compounded by the syphilis he had contracted in his early days. He was considered insane in 1891 and died two years later, a month short of his 43rd birthday, on July 6, 1893.

Guy de Maupassant is buried in the Cimetière du Montparnasse, Paris.

Maupassant is one of the fathers of the modern short story. Unlike the more psychologically oriented Turgenev and Chekhov, Maupassant delights in clever plotting, and served as a model for Somerset Maugham and O. Henry in this respect. His stories about real or fake jewels ("La parure", "Les bijoux") are imitated with a twist by Maugham ("Mr Know-All", "A String of Beads") and Henry James ("Paste"). As a stylish writer with a huge popular appeal he may be compared to Georges Simenon.