The penalty imposed on Mr. Tarrio at a three-hour hearing in Federal District Court in Washington was the final sentence to be lodged against the five members of the Proud Boys who were tried on seditious conspiracy charges earlier this year.

In a series of separate prosecutions — of which Mr. Tarrio’s sedition trial was by far the most important — the Justice Department all but decapitated the group’s national leadership and mostly put an end to its involvement in large-scale and often violent pro-Trump rallies in cities across the country.

Conor Mulroe, a prosecutor on the case, had urged Judge Kelly to sentence Mr. Tarrio to 33 years in prison, saying that a stiff penalty was needed to prevent extremists from attacking the democratic process in future elections.

Mr. Mulroe said that Mr. Tarrio has never showed true remorse for the Capitol attack, noting that even as a jury was deliberating his fate he gave an interview in front of thousands of people online declaring that the Proud Boys did nothing wrong on that day.

Days after weeping at his own sentencing, Mr. Biggs called into a vigil being held outside the municipal jail in Washington that houses several Jan. 6 defendants, describing his punishment as “insane” and declaring, “We gotta stand up and fight — don’t give up.”

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