The LSD becomes the third major opposition party to shutter in Hong Kong in the past two years.
Co-founded in 2006 by former lawmaker Leung Kwok-hung as a radical wing of the pro-democracy camp, the LSD is the last group in Hong Kong to stage small protests this year.
Mass public gatherings and marches spearheaded by political and civil society groups had been common in Hong Kong until 2020, but the threat of prosecution has largely shut down organised protests since.
China imposed a national security law on the former British colony in 2020, punishing offences like subversion with possible life imprisonment following mass pro-democracy protests in 2019.
A second set of laws, known as Article 23, was passed in 2024 by the city's pro-Beijing legislature covering crimes such as sedition and treason.
Current chair Chan Po-ying said the group had been "left with no choice" and after considering the safety of party members had decided to shutdown. Chan declined to specify what pressures they had faced.
"We have endured hardships of internal disputes and the near total imprisonment of our leadership while witnessing the erosion of civil society, the fading of grassroots voices, the omnipresence of red lines and the draconian suppression of dissent," Chan told reporters.
In February, the Democratic Party, the city's largest and most popular opposition party, announced it would disband.
Several senior members told Reuters they had been warned by Beijing that a failure to do so would mean serious consequences including possible arrests.
Earlier this month, China's top official on Hong Kong affairs, Xia Baolong, stressed national security work must continue as hostile forces were still interfering in the city.
"We must clearly see that the anti-China and Hong Kong chaos elements are still ruthless and are renewing various forms of soft resistance," Xia said in a speech in Hong Kong.
The League of Social Democrats is one of Hong Kong's smaller pro-democracy groups known for its more aggressive tactics and street protests in its advocacy of universal suffrage and grassroots causes including a universal pension scheme.
Chan told reporters the party had no assets to divest and no funds left after several of its bank accounts were shut down in 2023.
While never as popular as the more moderate Democratic Party and Civic Party, it gained three seats in a 2008 legislative election - its best showing.
The LSD's founder Leung, 69, was arrested and charged with conspiracy to commit subversion in 2021 in the landmark '47 Democrats' case. He is currently serving a sentence of six years and nine months in prison.
