A federal judge has handed down an eight-month prison sentence to Floridian Paul Hodgkins for his role in the 6 January attack on the US Capitol.
It makes him the first among hundreds of accused rioters facing prosecution to be imprisoned.
Hodgkins, 38, pleaded guilty on 2 June to obstruction of an official proceeding.
Congress was in the process of formally certifying Joe Biden's election last November as US President when supporters of former president Donald Trump rampaged through the building.
At a sentencing hearing today, prosecutor Mona Sedky told US District Judge Randolph Moss that Hodgkins, a Tampa resident, donned goggles before entering the Senate chamber during the riot and "proudly posed for selfies," which he texted to friends.
Ms Sedky acknowledged that Hodgkins did not destroy any property "and he did not injure anyone".
In a statement to the court, Hodgkins said he was "remorseful and regretful" for his actions in Washington and acknowledged that these actions may have emboldened others to engage in destructive acts.
"This was a foolish decision on my part that I take full responsibility for," Hodgkins told the court.
Judge Moss agreed that Hodgkins had not been violent, did not threaten anyone and did not organise the Capitol attack.
But the judge said that Hodgkins went to the Capitol "to impede the certification of the election, and he admitted that he did so".
The judge said that while he believes that Hodgkins' participation in the riot was an "aberration in his life", he also believed that the 6 January attack had "tarnished" US history and that it is necessary to deter future rioters.
More than 535 people have been charged with taking part in the attack, an unsuccessful attempt to stop Congress from certifying Mr Biden's victory over Mr Trump.
Mr Trump had falsely claimed the election was stolen from him through widespread voting fraud.
While other accused rioters have entered guilty pleas, Hodgkins became the first to be sentenced to prison.