From small spaniels to large labs, the canines were judged on factors including how long they could stay on their board, the size of the wave and their confidence.
In its 10th year, the contest in Pacifica, about 20km south of San Francisco on Saturday, includes a pet adoption event and fundraising for local animal charities.
The dogs, sporting their colourful life vests, stood ready on their surfboards and were helped by human participants, who spotted the best wave to carry the board to the beach.
Spectators erupted in applause and cheered with each successful ride.
Sophia Sadlowski first put her Miniature Pinscher, Rusty, on her surfboard to capture fun photos when he was just a puppy.
"And then ... he didn't want to get off," said Sadlowski, of Huntington Beach, California.
"I walk over to the beach, and I put him on a wave, and he surfed it."
Small, medium and large dogs competed in heats and then the highest scoring dogs in each heat faced off for the top prize. The day also included tandem contests, where multiple dogs, as well as dogs and humans, shared the surfboard.
Rusty's life jacket was green with animal print and a shark fin sticking up out of his back and his goggles gave the impression he was a fierce competitor for the small-sized and tandem dog competitions.
Sadlowski said Rusty was in his first surf competition at four months old, and she and her pup are now both cancer-free.
"He was four months old, and he took third place. So we've been surfing since," Sadlowski said.
"We got hooked."
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