The Hugo Awards, given for science fiction and fantasy works, were presented Sunday in Chicago at the 70th World Science Fiction convention.
It is the second big win for Among Others, which also took the Nebula Award.
The author, born in Wales and now living in Montreal, writes science fiction and fantasy novels, and also designs role-playing games.
An earlier novel, Tooth and Claw, won the World Fantasy Award. Among Others is also a finalist for that award, given in November.
Among Others has also been recommended by the School Library Journal as a one of the year’s best adult titles for teens.
It follows a heroine called Morwenna Phelps, who has been raised by a half-mad mother who practises dark magic and is lured to magic herself after being sent to a boarding school in England.
The publisher describes the novel as both a “diary of first encounters with the great novels of modern fantasy and science fiction, and a spellbinding tale of escape from ancient enchantment.”