The 78-year-old newspaper founder has been behind bars since 2020, and has served time for other criminal convictions.

Here is how Lai's penalty works:

- How was the sentence calculated? -

Lai was found guilty of two counts of conspiracy to commit foreign collusion under the national security law, which comes with a sentencing range of 10 years to life for crimes "of a grave nature".

He also faced one count of conspiracy to print seditious publications under a colonial-era law, which has a maximum jail term of two years for first-time offenders.

It is up to the judges to decide whether and how these jail terms can overlap.

The judges said they settled on 20 years' imprisonment "having stepped back and taking a global view of the total sentence for Lai's serious and grave criminal conduct".

His sentence is by far the harshest handed out under the national security law, surpassing the previous record of 10 years given to legal scholar Benny Tai in 2024.

- Why was the sentence reduced? -

In 2022, Lai was given a jail sentence of five years and nine months after being found guilty of fraud in a contractual dispute.

Lai was still serving time as of Monday.

Judges ruled that two years from the newly delivered sentence will overlap with his existing penalty.

In effect, Lai will add 18 years to his prison stint.

- Other defendants -

Judges also sentenced eight of Lai's co-defendants on Monday, including six people from Apple Daily's senior management.

Top editors Ryan Law, Lam Man-chung and Fung Wai-kong each received 10 years.

The remaining three -- Cheung Kim-hung, Chan Pui-man and Yeung Ching-kee -- received shorter sentences as they testified against Lai, with Cheung getting six years and nine months.

Wayland Chan Tsz-wah and Andy Li, two younger men who pleaded guilty to conspiring with Lai to lobby Western nations, received sentences of up to seven years and three months.

- What's next? -

Lai will have 28 calendar days to lodge an appeal, his defence lawyer Robert Pang told AFP -- though he declined to say if the tycoon will take that step.

Authorities say that Lai has been kept in solitary confinement at his own request and that he has received adequate medical care behind bars.

A homegrown national security law passed in 2024 made it much harder for people jailed for national security crimes to secure early prison release on the grounds of good behaviour.

If Lai serves out his sentence in full, he will likely be 96 before regaining his freedom.