Tropical Storm Rumbia brought rain and strong winds as demonstrators bearing banners saying "Democracy now" and "Down with the Chinese Communist Party" started off from the city's landmark Victoria Park to march to the financial district of Central.
The annual rally for democracy comes amid concerns in the southern Chinese city that Beijing is increasingly meddling in local affairs.
A widening income gap and soaring property prices have also contributed to the turnout as protesters focused their anger on unpopular Chief Executive Leung Chun-ying.
The July 1 rally comes after a survey published by the Hong Kong University found that only 33 percent of Hong Kongers took pride in being a Chinese national, the lowest level since 1998.
More From This Section
Leung was appointed by a pro-Beijing committee last July, promising to improve governance and uphold the rule of law in the territory of seven million people.
He is charged with overseeing the transition to universal suffrage to appoint the city's leader, which was promised by 2017, though critics say little or no progress has been made on the issue as the deadline draws nearer.
"With the greatest sincerity and commitment, the SAR government will launch a consultation at an appropriate juncture," he added.
"People don't want elections with Chinese characteristics. The government should start consultation now so Hong Kong can have genuine democracy," protester Yeung Yuk, a 28-year-old social worker, told AFP.
According to a poll conducted by the Hong Kong University released last week, Leung's approval rating stands at 46.2 percent.