The Democratic Party has been Hong Kong's flagship opposition since its founding three years before the financial hub's return to Chinese rule from the United Kingdom in 1997.
At the end of the 1990s, the Democratic Party was the largest opposition party, with as many as 13 members of the 60-seat Legislative Council.
It used to sweep city-wide legislative elections and push China on democratic reforms and upholding freedom.
However, mass pro-democracy protests in 2019 against a perceived tightening of China's grip on the city prompted authorities in Beijing to enact a sweeping national security law to stifle dissent.
On Sunday, members of the Democratic Party voted to disband the party and to enter liquidation, chairman Lo Kin-hei told reporters after an extraordinary general meeting.
"To have journeyed through these three decades, shoulder to shoulder with the people of Hong Kong, has been our greatest honour. Throughout these years, we have always treated the well-being of Hong Kong and its people as our guiding purpose," Lo said.
Of 121 votes cast, 117 voted to disband while four abstained.
Senior party members previously told Reuters they had been approached by Chinese officials or middlemen and told to disband or face severe consequences, including possible arrest.
There was no immediate response to a request for comment from the Hong Kong Liaison Office, China's main representative body in Hong Kong.
Emily Lau, a former Democratic Party chairwoman, expressed regret at the vote's outcome.
"Why does an organisation that has done so much for Hong Kong need to end like this? I find it very problematic," she said.
China's "one country, two systems" arrangement promises Hong Kong a high degree of autonomy.
However in recent years, authorities have used new security laws to arrest scores of opponents, disband civil society groups and close media outlets.
"We were never able to have democracy. We never had the chance to elect our government ... We hope it (the principle of one country, two systems) won't keep shrinking more and more. We hope there won't be more and more people being arrested," Lau said.
The vote to disband comes a week after Hong Kong held a "patriots only" legislative council election and one day before media mogul and China critic Jimmy Lai receives a verdict in a landmark national security trial.
China's move in 2021 to overhaul Hong Kong's electoral system - allowing only those vetted as "patriots" to run for public office - marginalised the Democratic Party by removing it from mainstream politics.
In June, another pro-democracy group, the League of Social Democrats, said it would disband amid "immense political pressure".
Senior Democratic Party members Wu Chi-wai, Albert Ho, Helena Wong and Lam Cheuk-ting have been jailed or held in custody under a national security law that China imposed in 2020 in response to mass pro-democracy protests the year before.
Some governments, including those of the United States and the United Kingdom, have criticised the law, saying it has been used to stifle dissent and individual freedom.
China has said no freedom is absolute and that the national security law has restored stability to Hong Kong.
with DPA
