The sharp slide in turnout since the last such election in 2019 comes after Beijing imposed a sweeping national security law that has been used to clamp down on dissent, and overhauled the electoral system to shut out democrats and other liberals.
"It can be seen that everyone has begun to feel that the election has no meaning," said Lemon Wong, one of the few remaining democrats still involved in local politics.
"Even pro-establishment supporters are asking themselves why they need to vote because it's all the same."
The previous lowest turnout was 35.8 per cent in 1999.
Four years ago at the last such election during Hong Kong's mass pro-democracy protests, a record 71 per cent turnout brought about a landslide victory for the democratic camp in a fiercely contested poll.
For this election, directly elected seats were slashed by nearly 80 per cent, while all candidates were required to undergo national security background checks and secure nominations from two pro-government committees.
At least three pro-democracy and non pro-establishment groups, including moderates, and even some pro-Beijing figures failed to meet those thresholds.
An unprecedented electronic poll register system failure caused some disruptions and an eventual switch to a manual system.
Security was tight, with more than 10,000 police deployed.
At least six people were arrested for alleged offences including posting online for people to cast invalid ballots, or to incite others to disrupt the polls, according to statements from the police and the city's anti-corruption authority.
Hong Kong's leader John Lee, who had sought in recent weeks to rally public support for the polls, again defended their legitimacy given a need to secure stability in Hong Kong that returned from British to Chinese rule in 1997.
While some western governments have been critical of Hong Kong's authoritarian turn under the national security law, China says it has brought stability to the financial hub after protracted pro-democracy protests in 2019.
