Helm was chosen for the award by a panel picked by the TV channel Dave, beating last year's winner Tim Vine.
"I needed a password eight characters long so I picked 'Snow White and the Seven Dwarves'," Helm's joke reads.
"I knew my joke was the funniest joke of all the other jokes in 2011," Helm said upon winning the award, reports BBC News. "Thank you to Dave and all the people that voted for proving me right."
Magician and comedian Paul Daniels was given the less prestigious award for worst joke of the festival.
"I said to a fella, 'Is there a B&Q in Henley?' He said, 'No, there's an H, an E, and N, an L, and a Y'," Daniels's joke reads.