Horacio Quiroga was born at Salto on the River Uruguay. His father, who was an Argentinian consular official, died in a shooting incident when Horacio was an infant. The family moved to Córdoba and returned to Salto in 1883. In 1891 the family moved to the capital, Montevideo where Quiroga studied for a short time at the university. He started to publish in local magazines from 1897 and was the founding editor of Revista de Salto (1899-90). After his stepfather's death - he shot himself - Quiroga visited Paris, where he fell under the influence of the French symbolist movement and the works of Poe. After returning to Uruguay, Quiroga published a volume pf Modernist poetry, Los arrecifes de coral (1902), and became the centre of a group of young writers.

Quiroga accidentally shot and killed his friend in 1902 while they were inspecting a gun. He left for Buenos Aires where he taught Spanish at the British School. He was the official photographer on an expedition, led by the poet Leopoldo Lugones, to Misiones in northeast Argentina. In 1904 he settled in Chano province. He planted cotton but the venture failed and he abandoned the project. In 1909 Quiroga married Ana María Cires, his pupil; they had one daughter, named Egle, and one son, named after the pseudonymous surname of Félix Sarmiento, Darío. Both these children later killed themselves. The family moved to San Ignacio, Misiones, on the river Paraná, where he assumed a post of registrar. Unable to tolerate the harsh conditions, Quiroga's wife poisoned herself six years later - she suffered a full week before she died. Alone with two children, Quiroga wrote a tender collection of children's stories. In 1916 he returned to Buenos Aires with his children. He worked at the Uruguyan consulate and in 1925 he returned to Misiones. Two years later he married María Elena Bravo, a friend of his daughter. The marriage ended in separation. In 1935 Quiroga was appointed Uruguay's honorary consul in San Ignacio.

Quiroga was plagued throughout his life by his illnesses. He suffered from mental disorder, and he began to drink to dispel his bouts of tension and anxiety. Quiroga was diagnosed as having cancer and he committed suicide on February 19, 1937, while he was still at the clinic.