Hong Kong pro-democracy activist Chan Kin-man has walked free from prison, saying he has no regrets for his leading role in the so-called "Umbrella" civil disobedience movement in 2014.

"Life in prison was difficult, but I have no regret at all ... as this is a necessary price to pay for fighting for democracy," Chan said, chanting "I want universal suffrage" with dozens of supporters.

A retired sociologist and one of the three leaders of the pro-democracy movement, Chan was found guilty last year of conspiracy to commit public nuisance for his role in planning and mobilising supporters during the 79-day protest that brought parts of the Chinese-ruled city to a standstill.

The Umbrella protesters staged peaceful sit-ins, blocking major roads in the Asian financial hub in a push for full democracy, although they failed to wrest concessions from Beijing.

The Umbrella movement got its name because activists used umbrellas to shield themselves from tear gas and pepper spray.

The symbolic umbrella tactic re-emerged in 2019 during the sometimes violent anti-government protests triggered by a now withdrawn extradition bill that would have allowed criminal suspects to be sent to the mainland for trial in Communist Party-controlled courts.

Many protesters last year said the 2014 movement prepared them for further fights for democracy.

Chan said he understood why the young protesters resorted to "intense actions" in the past few months because they felt the government was no longer fair and just.

"I think after the last few months, Hong Kong people understand more why we had to use civil disobedience to fight for freedom," the 61-year-old said.

Chan said he plans to visit the young protesters arrested during the recent unrest and share with them his experience in how to mentally deal with the charges they face.

Hong Kong returned to China from British rule in 1997 under a "one country, two systems" formula that guarantees freedoms not enjoyed on the mainland but many activists accuse Beijing of tightening its grip on the city and eroding those freedoms.

Beijing denies meddling and blames the West for fomenting unrest.