The first rioter to breach the U.S. Capitol on Jan. 6, 2021, was sentenced Tuesday to more than four years in prison, federal prosecutors announced.

In March, a federal jury found Michael Sparks, 47, of Elizabethtown, Ky., guilty on felony charges of obstructing an official proceeding and civil disorder and several misdemeanor charges for being on the premises of the Capitol building on Jan. 6.

On Tuesday, Judge Timothy J. Kelly of U.S. District Court in Washington sentenced him to 53 months in prison and ordered him to pay a $2,000 fine. Mr. Sparks will be on supervised release for three years after his prison term ends, prosecutors said.

Video footage presented in court showed that Mr. Sparks entering the Capitol building at 2:13 p.m. on Jan. 6 through a window near a door leading into the Senate Wing that rioters had smashed with a police shield.

Mr. Sparks was among the initial group of rioters who were confronted by Eugene Goodman, a Capitol Police officer, who helped hold off the mob from reaching members of Congress.

The rioters chased Mr. Goodman up a flight of stairs as they demanded to know where Congress was certifying the results of the election, prosecutors said.

At the top of the stairs, Mr. Goodman and other officers faced off with the agitated mob, prosecutors said, including Mr. Sparks, who yelled “This is our America!,” at the police officers.

In court, Mr. Sparks’s lawyer, Scott T. Wendelsdorf, argued at sentencing that the focus on his client’s status as the first to enter the Capitol was misplaced and that what really mattered was “how long he was there and what he did while inside.”

In a sentencing memo asking the judge for a sentence of one year under house arrest followed by three years of supervised release, Mr. Wendelsdorf tried to draw a distinction between his client’s actions and the violent actions of other rioters. Mr. Wendelsdorf noted that Mr. Sparks never assaulted or threatened an officer and that he left the Capitol building 20 minutes after he entered.

“Michael Sparks may have started the game, according to the government, but he was out of the game on the sidelines before the first quarter was over,” Mr. Wendelsdorf said at trial in March.

Prosecutors had asked Judge Kelly to sentence Mr. Sparks to 57 months in prison — four more than he eventually got — and three years of supervised release.

Mr. Sparks’s forced entry, they said in a sentencing memo, had immediately set off “the forced interruption of the 2020 Electoral College vote count and threatening the peaceful transfer of power after the 2020 presidential election.”

Judge Kelly’s view appeared to be in line with that characterization. The judge said Tuesday that it was undeniable that Mr. Sparks’s entry would have “an emboldening and encouraging effect on everyone who was at least in your vicinity,” according to The Associated Press.

“To say it wasn’t a material, key point in the mob’s taking of the Capitol, I think, is just ignoring the obvious,” the judge added, according to The A.P.

During the trial, the prosecution had also honed in on remarks Mr. Sparks had made on social media in the days leading up to Jan. 6, including a post on the social media site Parler calling for a civil war. He also posted on Facebook three days before the Capitol breach, prosecutors said.

“It’s time to drag them out of Congress,” he wrote in a post. “It’s tyranny.”

Mr. Sparks, who had a job supervising a factory in Cecilia, Ky., turned himself in to the authorities on Jan. 19, 2021.

He did not testify at trial, but Mr. Sparks did submit a letter ahead of his sentencing in which he stated that one of his only regrets was that the events of Jan. 6 “did not change anything.”

On Tuesday, he reaffirmed before Judge Kelly that he still believed the false claim that the 2020 election was “completely taken from the American public,” The A.P. reported.

Messages to Mr. Sparks’s lawyer on Tuesday evening were not immediately returned.

Mr. Sparks is the latest to be sentenced of the more than 1,300 people the Justice Department has charged in connection with the Jan. 6 Capitol riots.