The Legislative Council break-in on July 1, 2019 saw protesters smashing windows, streaming inside the building in public anger over an extradition bill that would have allowed authorities to send people to mainland China for trial.
It was a pivotal moment in the months of civil unrest in the city which marked the boldest uprising against the Chinese Communist Party since the 1989 Tiananmen Square protests in Beijing.
In sentencing, District Court judge Li Chi-ho described the incident as a "serious" blow to the city's rule of law.
He sentenced actor Gregory Wong, who was earlier found guilty of rioting, to six years and two months in prison.
During the trial, Wong said he entered the Legislative Council solely to deliver chargers to reporters covering the break-in.
Political activist Ventus Lau received a sentence of around four-and-a-half years and activist Owen Chow was sentenced to over five years in prison.
Rioting holds a maximum seven-year sentence in Hong Kong's district court.
More than 10,000 people were arrested in relation to the 2019 Hong Kong protests.
Police figures say over 2,900 people have been charged so far with offenses including, rioting, unlawful assembly and criminal damage.
