Johnston briefly addressed a Washington, D.C. court on Monday before his sentencing, ABC News reported, describing his role in the attack as “reprehensible.”

Judge Carl Nichols cited Johnston's successful acting career as making his participation “all the more inexplicable and disturbing.”

Based on body camera and CCTV footage, authorities said Johnston “along with other rioters participated in a group attack” on police officers guarding an entrance to the Capitol and “helped retrieve a stolen police riot shield.”

A police officer was injured at this west entrance.

According to U.S. prosecutors, Johnston showed little remorse for his actions while demonstrating “a clear knowledge of the violence the rioters used that day and their involvement in it.”

As evidence, prosecutors pointed to a picture showing Johnston dressed as a so-called “QAnon Shaman” at a Halloween party two years after the 2021 incident.

Prosecutors also said that in the days after the riot, Johnston sent messages to friends and family claiming the severity of the attacks had been “exaggerated by the media.”

Johnston's attorney, Stanley Woodward, wrote in a sentencing memo that his client was unfairly targeted “because he is an acclaimed Hollywood actor and the government is using his status to make a statement to the public.”

Johnston has been “essentially blacklisted from Hollywood” and “has been working as a handyman for the past two years – obviously far removed from his actual expertise and livelihood in film and television,” Mr Woodward argued.

Johnston had supporting roles in the hit comedy “Anchorman” and on television in “Mr. Show,” “Arrested Development” and “Bob's Burgers,” where he lent his voice to fan-favorite character, Italian restaurateur Jimmy Pesto.

Nearly 1,500 people have been charged in connection with the January 6, 2021 riots. According to the U.S. Department of Justice, nearly 900 people have pleaded guilty to various crimes and more than 180 have been convicted in court.

Republican presidential candidate Donald Trump has said he would pardon some or all of the rioters – whom he has described as “hostages” and “political prisoners” – if he wins the Nov. 5 election.

He did not specify who he would release or what criteria he would use to select them.