The court on Tuesday disqualified lawmakers Sixtus "Baggio" Leung and Yau Wai-ching in the wake of an intervention by China that critics said undermined Hong Kong's judicial autonomy.
Leung and Yau said at a press conference Tuesday night that the court's decision reflected how elections in the semi-autonomous city were "meaningless."
Leung expressed his disappointment at the ruling. "The system we believed in -- that we see as protection for Hong Kong people -- is very fragile," he said.
Leung and Yau inserted curse words into their oaths of office and displayed flags bearing the words "Hong Kong is not China" during a ceremony in October.
Last week, China's top ruling body waded into the dispute
, invoking a rarely used power to decree that taking the oath in a "dishonest, ungraceful manner is also a refusal to the oath, and it shall be void."
The court also ruled Tuesday that Leung's and Yau's oaths were "invalid and void and have no legal effect" and that they could not retake them.
Their seats were ruled vacant.
The intervention by China's National People's Congress sparked widespread protests and outrage in Hong Kong.
Last week, hundreds of lawyers staged a silent march against the ruling, which they said undermines the city's judicial independence.
Alan Leong, a former lawmaker and co-founder of the Civic Party, denounced the move as "completely unnecessary."
He warned that any threats to the city's rule of law could be disastrous for its international reputation.
"I'm sure ratings agencies like Moody's are watching closely and will downgrade Hong Kong again," Leong told CNN. In March, the ratings agency changed its outlook
on Hong Kong from stable to negative.
Eddie Chu, who was elected to office at the same time as Leung and Yau, said the ruling "threatens to undermine the very foundations of Hong Kong's prosperity."
More lawmakers under threat
Many pro-Beijing groups have seen the decision against the pair as an opportunity to unseat other pro-democracy legislators.
Last week, a representative for the Voice of Loving Hong Kong, a pressure group, filed a writ with the High Court seeking to challenge the legitimacy of 11 other lawmakers, according to the South China Morning Post
Chu, who is named in the case, told CNN he will try and stay in the legislature.
"But if I am ejected I will keep fighting," he said.