The League of Social Democrats on Sunday announced its disbandment after 19 years of operation.
Chairwoman Chan Po-ying said members made the unanimous decision after considering the situation facing the group and its companions.
She also told a press conference that the group will deregister as a society, but that it has no assets to deal with since it has held no bank account for years.
Any cash the group has left, Chan said, would be used to settle debts and taxes.
The party was founded in 2006. In recent years, prominent members such as Leung Kwok-hung, Raphael Wong and Jimmy Sham have been jailed over different cases.