Gareth Brown, online editor of Blunt, told dotJournalism that he had been unable to hear the judges’ commendation when he accepted the award because runners up had been jeering so loudly.
"We were completely surprised to win. The other sites had proper funding, and some of them were built by external companies," he said.
"Ours was all our own work."
Judges commended the site for its quirky, irreverent style – despite fierce competition from the University of Durham, University of Bath and University of Southampton.
The site was built in 2002 by Gareth Brown and fellow student Fred Dutton as part of their Magazine Journalism course at Cardiff University.
For their efforts, the students won £500 cash, return flights on Easyjet and work experience at Guardian Unlimited. Awards were presented by Radio One presenter Colin Murray at a ceremony at Millbank in central London.
Mr Brown is now working on a new publication for backpackers, which will involve a web resource of news, information and community features for 18-25s.
"We want to include blogs, so that people can write about their travel while they are away," he said.
"I’m excited by the idea of creating an online community."
The Guardian Student Media Awards are now in their 25th year and award prizes in 13 categories including best newspaper, best budget publication and best reporter. This year's judging panel included Guardian editor Alan Rusbridger, Jon Snow of Channel 4 News, Vogue editor Alexandra Shulman and Rebekah Wade, editor of The Sun.