A total of 47 pro-democracy activists were arrested and charged in 2021 with conspiracy to commit subversion under a Beijing-imposed national security law that carried sentences of up to life in prison.
Benny Tai, a former legal scholar alleged to be a "mastermind" of the activists' plans, was on Tuesday sentenced to 10 years' jail, the longest sentence so far under the 2020 national security law.
The charges related to the organising of an unofficial "primary election" in 2020 to select the best candidates for a legislative election.
Prosecutors accused the activists of plotting to paralyse the government by engaging in potentially disruptive acts had they been elected.
Legal scholar Benny Tai was handed the longest jail sentence so far among the activists. (AP PHOTO)
Some Western governments have criticised the trial, with the US describing it as "politically motivated" and saying the democrats had been legally and peacefully taking part in political activities.
The Chinese and Hong Kong governments say the national security laws were necessary to restore order after mass pro-democracy protests in 2019.
After a 118-day trial, 14 of the democrats were found guilty in May, including Australian citizen Gordon Ng and activists Owen Chow and Gwyneth Ho, while two were acquitted.
The other 31 pleaded guilty and all 45 were given sentences ranging from four to 10 years.
"Our true crime for Beijing is that we were not content with playing along in manipulated elections," Ho, who was sentenced to seven years' imprisonment, wrote in a Facebook post.
"We dared to confront the regime with the question: will democracy ever be possible within such a structure? The answer was a complete crackdown on all fronts of society."
Australian Foreign Minister Penny Wong said she was "gravely concerned" about the sentences, and called on China to "cease suppression of freedoms of expression, assembly, media and civil society" in Hong Kong.
Chinese foreign ministry spokesman Lin Jian told reporters that "no one can engage in illegal activities in the name of democracy and attempt to escape legal punishment", adding Beijing "firmly supports" Hong Kong's efforts to safeguard national security.
Chow was sentenced to seven years and nine months in jail, while prominent activist Joshua Wong was sentenced to four years and eight months in jail, and Hendrick Lui was sentenced to more than four years in jail.
Hundreds of people queued from the early hours to secure a seat for the proceedings. (AP PHOTO)
Afterwards, Lui's mother Elsa Wu shouted: "He's a good person ... he's not a political prisoner ... why does he have to go to jail?"
Judges Andrew Chan, Alex Lee and Johnny Chan wrote that they considered factors including the degree of planning, the number of people involved, and the potential harms, in a "holistic assessment" irrespective of whether the scheme would have taken place or not.
The judges granted a one-third reduction in the sentences for some who pleaded guilty, including Tai.
Hundreds of people had queued for hours outside the court in light rain as they tried to secure a seat within the main courtroom and several spillover courts.
Authorities deployed a tight police presence outside the West Kowloon Magistrates Court and for several blocks with police dogs, an armoured truck and vehicles with lights flashing.
The ruling, which critics have said tarnishes Hong Kong's role as a global financial hub, comes as the city is hosting an international financial summit to attract more business.
US President-elect Donald Trump's nominee as secretary of state, Marco Rubio, has been a staunch critic of the trial and in an earlier open letter criticised the convictions as evidence of the national security law's "comprehensive assault on Hong Kong's autonomy, rule of law, and fundamental freedoms".
Outside the court building, Roxie Houge, the head of the US consulate in Hong Kong's political section, said the US government condemned "the continuous prosecution of individuals here in Hong Kong who are expressing their political views ... exercising their freedom of speech".
Taiwan's presidential office condemned the jailings, saying democracy and freedom were universal values and Taiwan would continue to stand in solidarity with Hong Kong.
