The convictions after a trial lasting nearly four months in federal court in Washington handed another victory to the US Justice Department as it pursues criminal charges against more than 1,000 people arising from the Capitol rampage by supporters of Republican then-President Donald Trump.
Several members of another far-right militia group, the Oath Keepers, were convicted in earlier trials.
In addition to Tarrio, Proud Boys members Ethan Nordean, Joseph Biggs and Zachary Rehl were convicted of seditious conspiracy - a plot to oppose the government with force - under a Civil War-era law. Conviction on the charge can carry up to 20 years in prison. Dominic Pezzola, the only one of the five defendants who did not play a leadership role in the Proud Boys, was acquitted of the charge.
The 12-member jury, which deliberated about a week, also found Tarrio, Nordean, Biggs, Rehl and Pezzola guilty of other felonies including obstructing an official proceeding, a charge that also can carry up to 20 years in prison. They also were convicted of conspiring to impede Congress from performing its duties and obstructing law enforcement during a civil disorder.
US District Court Judge Timothy Kelly declared a mistrial on a few outstanding counts after jurors said they could not reach a consensus.
The Justice Department welcomed the jury's verdicts.
"The government's evidence at trial demonstrated the crucial role that these men and their followers played in breaking through the multiple security lines that protected the Capitol on January 6, 2021. Their crimes, and the crimes of other members of the mob that descended on the Capitol, struck at the very heart of our democracy," said Matthew Graves, the US attorney in the District of Columbia.
More than 500 people have pleaded guilty to charges brought by the Justice Department related to the Capitol riot and about 80 others have been convicted during trials. These included Oath Keepers founder Stewart Rhodes and several of that group's members.
The trial of the Proud Boys members was the longest of any of those arising from the Capitol attack, with the jury hearing about 50 days of testimony since January.
The jury was unable to unanimously reach a verdict on whether to convict Pezzola for conspiracy to obstruct an official proceeding, though they found the other defendants guilty of that charge. The jury also did not reach a verdict for all the defendants on some other charges related to property destruction at the Capitol and assaults against law enforcement.
During closing arguments, prosecutor Conor Mulroe said the Proud Boys viewed themselves as a "fighting force lined up behind Donald Trump and ready to commit violence on his behalf" in order to overturn his 2020 election defeat.
Prosecutors told jurors that Tarrio and the other defendants, some of whom led state chapters, purchased paramilitary gear for the attack and urged members of the self-described "Western chauvinist group" to descend on Washington.
Defense lawyers told the jury their clients had no plans to attack the Capitol and had traveled to Washington merely to protest. The defense also sought to blame Trump, saying he was the one who urged protesters to descend on the Capitol.
"They want to use Enrique Tarrio as a scapegoat for Donald Trump and those in power," Tarrio's attorney Nayib Hassan said of prosecutors during his closing argument.
Of the five defendants, all but Tarrio entered the Capitol during the attack, with prosecutors saying they were among the first to charge past barricades erected to protect the building. Tarrio was not in Washington that day, but prosecutors said he helped direct the attack from Baltimore after being ordered by a judge to stay out of Washington following his Jan. 4 arrest for burning a Black Lives Matter banner at a church.
The rampage occurred on the day when Congress was voting on formally certifying Biden's victory in the November 2020 election, with rioters attacking police with a variety of weapons. Shortly before the riot, the Republican Trump gave an incendiary speech to supporters urging them to go to the Capitol and "fight like hell" and repeated his false claims that the election was stolen from him throughout widespread voting fraud.
Five people including a police officer died during or shortly after the riot. More than 140 police officers were injured.
