The Troop, by Canadian author Craig Davidson, was announced as the winner of the Â£2,000 prize on Wednesday night.
The award was set up to celebrate the life and work of horror writer James Herbert who died in March 2013.
Herbert's daughter Kerry, who was one of the judges, described the winning book as the "darkest of tales".
"My father would have chuckled in his chair; his fans will love it. And you'll never go camping again," she said.
"The Troop is a brilliant and terrifying classic that I am proud to champion as the first winner of the James Herbert Award for Horror Writing - it's now one of my favourite books."
The book was written by Davidson under the pseudonym of Nick Cutter.  It tells the story of scoutmaster Tim Riggs and his troop of boy scouts who encounter an "emaciated stranger" on a camping trip in the Canadian wilderness.
The chair of judges, Tom Hunter, said: "The Troop is a perfect first winner, and the judges loved its tense plotting, detailed characterisation and above all the driving sense of fear that compels you to keep turning every horror-soaked page until the end."
Born in Toronto, Ontario, Davidson's other works include his first short story collection, Rust and Bone, which was adapted into a film by French director Jacques Audiard starring actress Marion Cotillard as a killer whale trainer.
Herbert was the author of 23 novels, including The Rats, The Fog, The Dark, The Survivor, The Magic Cottage, Haunted and Fluke.
A novel about a scout camping weekend that takes a scary twist has won the first James Herbert award for horror writing.