That result surpassed the 30.2 per cent in the 2021 election, the first held under the new system.
It was much lower than before the electoral changes, when turnout topped 50 per cent.
Many of the city's 4.1 million eligible voters, especially democracy supporters, have turned away from politics since a crackdown that has stifled dissent.
Candidates must now go through a vetting process that ensures they are patriots who are loyal to the Chinese government.
The government says the changes were needed to bring stability after massive anti-government protests in 2019.
The government launched a major campaign to drive up turnout, adding polling stations, extending voting hours and holding candidate forums.
But public anger over government accountability in an apartment fire that killed at least 159 people late last month threatened to keep some potential voters at home.
In the end, enough came out to nudge up the turnout rate from 2021.
"I'm performing my civic duty as a citizen to vote … but I'm not too certain which candidate is hardworking and which is not," retiree Kwan Lam said outside a polling station.
"I chose the one who cares for the elderly."
Ahead of the vote, Chinese authorities called foreign media to a rare meeting to warn them that they need to comply with the city's national security laws.
Election campaigning was suspended after the fire and remained subdued in the final days out of respect for the victims.
Government efforts to drive up turnout, seen as a referendum on the new electoral system, had been in full swing before the blaze.
Promotional banners and posters were hung throughout the city and subsidies offered to centres for older people and people with disabilities to help them vote.
Authorities arrested people who allegedly posted content that incited others not to vote or cast invalid votes.
Hong Kong's deadliest fire in decades has raised questions over government oversight and allegations of bid-rigging in building maintenance projects.
The 1980s-era apartment complex was undergoing renovations.
Some candidates pledged to combat bid-rigging.
City leader John Lee said last week that going ahead with the election, rather than delaying it, would better support the response to the fire.
"They have all experienced this fire and shared the pain," he said of the city's Legislative Council.
"They will certainly work with the government to promote reforms, diligently review funding and draft relevant laws."
Even before the 2021 electoral changes, only half of what had been a 70-member legislature was chosen by the general electorate.
Now, that has been reduced to 20 out of 90 seats and 40 others are chosen by a largely pro-Chinese election committee.
The remaining 30 represent various groups - mainly major industries such as finance, health care and real estate - and are elected by their members.
The "patriots" requirement for all candidates has pushed out the opposition parties, which advocated for making the system more democratic.
Authorities have warned the general public against using the fire to try to undermine the government and have arrested at least one person on suspicion of inciting hatred against government officials.
