But after a peaceful start, violence erupted near the march within hours, with police and masked protesters facing off in several neighbourhoods on the city's main island.
The Civil Human Rights Front, the umbrella group which organised the march, said authorities ordered them to end it after the clashes began.
"We believe the total turnout for today's march has surpassed the 1.03 million on June 9," the group announced, referring to the massive rally last year that kicked off the protest movement in earnest.
The police gave a far lower estimate of 60,000, a number the CHRF said was "too ridiculous".
In now-familiar scenes, riot police used pepper spray, tear gas and water cannon, while hardcore protesters lobbed petrol bombs, built makeshift barricades and vandalised property belonging to businesses they consider pro-Beijing - including Starbucks and banking giant HSBC.
Police said around 400 people were arrested for offences including "unlawful assembly and possession of offensive weapons".
The Wednesday clashes were, however, small compared with some of the chaos witnessed in the city in recent months.
The unrest in Hong Kong was sparked last year by a proposal to allow extraditions to mainland China. It has since morphed into a larger revolt against what many fear is Beijing's tightening control over the semi-autonomous city.
China and the Hong Kong administration have refused to accede to the protesters' demands, which include fully free elections in the city, an inquiry into alleged police misconduct, and amnesty for the nearly 7,000 people arrested during the movement - nearly a third of them under the age of 20. "It is sad that our demands from 2019 need to be carried forward to 2020," the CHRF's Jimmy Sham said at the start of the rally.