Activists descended on key subway stations during the morning rush hour, deliberately keeping open doors to stop trains departing, causing long queues and triggering occasional scuffles between angry commuters and protesters.
More than 100 flights at the city's airport -- one of the world's busiest -- were also listed as cancelled on Monday morning after aviation authorities warned passengers about potential disruptions.
While some commuters were angered by the morning transport chaos, others said they supported the action after more than two months of extraordinary protests aimed at securing democratic freedoms.
"As long as the government doesn't respond then for sure the movement will escalate," a civil servant, who gave his surname as Leung, told AFP as he tried to make his way to work.
The office of city leader Carrie Lam -- who has kept a low public profile as the protests have escalated -- announced she would hold a press conference later Monday morning.
The strike -- a rare sight in a freewheeling finance hub where unions traditionally have little sway -- is aimed at showing Beijing that there is still broad public support for a protest movement that keeps hitting the streets but has so far won few concessions.
The protests in the semi-autonomous southern Chinese city were triggered by opposition to a planned extradition law but quickly evolved into a wider movement for democratic reform and a halt to eroding freedoms.
Authorities in Hong Kong and Beijing have signalled a hardening stance with the Chinese military saying it is ready to quell the "intolerable" unrest if requested.
Dozens of protesters have been charged with rioting, a charge with a maximum penalty of 10 years in jail.
Over the weekend riot police fired tear gas at protesters in multiple districts throughout Saturday and Sunday night.
The largely leaderless protest movement uses social messaging apps to coordinate.
At a press conference on Saturday, strike organisers -- many hiding their identities behind masks -- said 14,000 people from more than 20 sectors had committed to civic action on Monday.
People from all walks of life indicated plans online to either strike or phone in sick on Monday -- from civil servants and social workers, to flight attendants, pilots, bus drivers and even employees of the city's Disneyland.
Given its reputation as a bastion for free-market capitalism, Hong Kong does not have much recent history of successful labour movements.
"There's a psychological barrier for people to strike," protester and pastor Monica Wong, 40, told AFP on Sunday as she attended a large rally.
"I really understand how some people will face huge pressures from their supervisors."
In a statement late Sunday, Hong Kong's government warned people against joining the strike, saying it could further hamper the city's already sputtering economy.
"Any large-scale strikes and acts of violence will affect the livelihood and economic activities of Hong Kong citizens," it said.
Alongside the strike, protesters plan to hold rallies in seven different parts of the city, the fourth day in a row that protests have been scheduled.
The past fortnight has seen a surge in violence on both sides with police repeatedly firing rubber bullets and tear gas to disperse increasingly hostile projectile-throwing crowds.
A group of men suspected to be linked to triads -- Hong Kong's notorious gangsters -- also attacked demonstrators, putting 45 people in hospital.
Under the terms of the 1997 handover deal with Britain, Hong Kong has rights and liberties unseen on the Chinese mainland, including an independent judiciary and freedom of speech.
But many say those rights are being curtailed, citing the disappearance into mainland custody of dissident booksellers, the disqualification of prominent politicians and the jailing of pro-democracy protest leaders.
Public anger has been compounded by rising inequality and the perception that the city's distinct language and culture are being threatened by ever-closer integration with the Chinese mainland.