Seattle “antifa” 1, Nazis 0.

“Anti-fascist” Twitter users banded together to track down — and then knock out — a man who was wearing a swastika armband around Seattle on Sunday.

A video clip, which has gone viral, shows the white Nazi sympathizer crumpling to the ground after being socked in the face by a much larger black man.

“Night-night,” a bystander says, moments after the man sporting the swastika gets laid out.

“Ain’t got nothing to talk about,” the puncher fumes.

Seattle police officials Monday confirmed reports of a man sporting a swastika armband, saying he was “instigating fights.” But the individual refused to cooperate when approached by officers.

“Police were on scene in 5 mins & found him on the ground. He declined to provide info about incident & left after removing his armband,” the department tweeted. “No one else at the scene contacted officers to make a report about the incident.”

According to Twitter users, the man who was wearing the armband was first spotted on a bus — Seattle’s D line, to be exact — where he was allegedly accosting a black man.

“Nazi s–t head seen on D line headed to downtown #Seattle,” wrote user @bigotbasher, an Emerald City resident.

“Submitter said they were harassing a black man on the bus,” he tweeted, along with a picture of the man.

Several self-described “anti-fascists” or “antifa” shared the image on Twitter in the attempt to find the Nazi fanatic, including an account called @teethnclaws — which posted a text saying the man had been seen on a street corner downtown, BuzzFeed reports.

He apparently was found minutes later, with one Facebook user posting a pic of the aftermath.

“Just watched a Nazi get knocked the f–k out,” wrote Sean Patrick Duff, who later spoke to BuzzFeed.

“I literally just got off a bus and was walking to a movie and saw some guy being obnoxious up the way — which I’m used to in downtown Seattle, but then I saw the Nazi armband and realize we are dealing with a guy a little more than just obnoxious,” he said. “I had eaten over 800mg of THC and was way too high for confrontation so I just held back with two other passersby to watch what would unfold.”

In the viral video, the man in the swastika armband can be heard telling his attacker that “they deserve the welfare” right before he gets socked in the face.

Anti-fascist Twitter accounts have been praising the puncher, including “New York City Antifa” and “Pacific Northwest Antifascist Workers Collective.”

“Having a bad day? This will cheer you up!” tweeted NYC Antifa, along with a clip of the knockout.

Most of the users who were involved in the swastika hunt have either deleted their tweets or made their accounts private. User @teethnclaws did, however, speak with BuzzFeed about the incident.

“I would say that we successfully identified, tracked and coordinated to neutralize a clear and present danger to Seattle. Whether we coordinated the actual punch or not,” he said, describing himself as an anti-fascist fighter.

“I, for one, applaud the anonymous hero.”