The northern Spanish terrain proved challenging, with a leading group of 13 riders still together up the final serious ascent before the last 40km to the finish line just outside the village of Maeztu.
Most of the leading group stuck together as they waited for an opportunity to make a late breakaway and Berrade seized his chance on the last climb with less than 5km to go.
For Kern-Pharma rider Berrade, who was born in the city of Pamplona not far from the route, the win felt especially sweet.
"It's a dream. The stage closer to home, with all my family watching me, friends, in the last stages of La Vuelta," said Berrade.
"I didn't see myself as the winner until I crossed the finish line. No doubt it comes from a great previous work that we (Kern-Pharma) have done."
Switzerland's Mauro Schmid secured second place and Spaniard Pau Miquel Delgado came third.
O'Connor maintained his five-second lead in the overall standings over Slovenian Primoz Roglic as the pair once again crossed the line together among a large group.
O'Connor admitted that the stage was not easy, but he did not think today's effort would have any impact on future stages.
"Probably not, because we raced every single day, and everyone is just tired. But somehow, I’m still managing to crack out some pretty good numbers, so I don’t think it makes any difference now," O'Connor said.
"And I’m still in the lead! It’s nice to have it for another day. I don’t know if it’s 13 or 14 days, a long time. I’ve loved it and I enjoyed it a lot."
Spain's Mikel Landa suffered a significant setback, dropping five spots to 10th place and falling further behind O'Connor. He now trails the leader by five minutes and 38 seconds, an increase of over three minutes, putting his race ambitions in jeopardy.
