Walle (WAHL-ee), a 4-year-old mutt from Chico, Calif., who was entered at the last minute, was judged most unsightly of 30 dogs at the Northern California competition.
"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 overcame the dominance in recent years by nearly hairless Chihuahuas, Chinese cresteds, or combinations of the two.
Owner Tammie Barbee got the dog when he was three months old.
"People come up to me and say that dog is not right," Barbee said, "but I love him."
Judges said they were especially impressed by Walle's bizarre waddle of a walk.
Walle wins $1,500 and will make several network TV appearances next week, including NBC's "Today" show and ABC's "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."