Jimmy Lai, the pro-democracy former Hong Kong media tycoon and a fierce critic of Beijing, was sentenced to 20 years in prison on Monday, after being convicted on national security charges late last year.

Mr. Lai, founder of the now-defunct newspaper Apple Daily, was a long-standing critic of China and backer of Hong Kong’s pro-democracy movement. He was arrested in 2020 during a crackdown that followed months of anti-government protests the year before, and charged under a national security law imposed on Hong Kong by Beijing. Mr. Lai was accused of sedition and colluding with foreign forces to undermine Chinese rule in the territory.

Judge Esther Toh said 18 years of Lai’s sentence should be served consecutively to his jail term in his separate fraud case, for which he received a term of five years and nine months. Lai can appeal his case. His co-defendants received jail terms between 6 years and 3 months and 10 years.

On Dec. 15, a panel of three judges, handpicked by Hong Kong leader John Lee to oversee sensitive national security cases, found there was “indisputable evidence” Mr. Lai had conspired with foreign actors to undermine the Chinese and Hong Kong governments, based on a lifelong “resentment and hatred” of the Communist regime in Beijing.