Huge-headed, duck-footed Walle is a 4-year-old mutt from Chico. He was entered at the last minute, after his owner kept getting so many comments about the dog's appearance.
"Everybody always says that there's something wrong with him - his head's too big, his back is too short. It's nice to win at something," said owner Tammie Barbee, who has had Walle since he was just 3 months old.
Judges said they were especially impressed by Walle's bizarre waddle of a walk.
"This dog looked like he's been photo-shopped with pieces from various dogs and maybe a few other animals," judge Brian Sobel said.
Walle and Barbee won $1,500 and will make several network TV appearances next week, including "Jimmy Kimmel Live."
The contest at the Sonoma-Marin Fairgrounds gets worldwide attention, with media from around the world traveling to Petaluma, about 40 miles north of San Francisco.
Organizers say the dogs are judged for their "natural ugliness in both pedigree and mutt classes."
The Associated Press contributed to this report.