They held up signs calling on the government to withdraw the extradition bill completely, while chants of "Free Hong Kong" reverberated around the cavernous glass and steel hall.
About two hours after the event started, protesters had filled up arrival hall A in Terminal 1 and were spreading out to arrival hall B.
The airport protest was a direct response to violent mob attacks last Sunday when hundreds of white-clad men stormed into a metro station in the northern suburban town of Yuen Long and indiscriminately attacked activists with weapons including wooden batons, canes and iron rods.
The demonstrations, mushrooming up nearly daily, saw the defacement of China's main representative office last weekend, triggering warnings from Beijing this was an attack on China's sovereignty.
Civil Servants from more than 40 of Hong Kong's various departments and bureaus have sent an open letter to the Hong Kong government threatening that "industrial action" (a strike or stoppage of work) will occur if the demands of protestors are not given proper attention.
Organisers billed the rally at the airport - one of the world's busiest - as an opportunity to brief arrivals on the political unrest, particularly visitors from mainland China where state-controlled news has portrayed the protests as a violent, foreign-funded plot to destabilise China.
Hong Kong returned to China under a "one country, two systems" formula, guaranteeing its freedoms - including rights to protest not enjoyed on the mainland - for at least 50 years.
"The world has been watching us in the past few weeks", said Jeremy Tam, a former pilot and lawmaker who helped organise the rally with other aviation sector employees.
The protests are "not only expressing grievances, but also showing that we don't support any illegal violence in our society and also that the social order can not be ignored by the police force in Hong Kong", said opposition lawmaker Au Nok-hin. He said the government took "a very serious attitude" toward the possibility of violence and said, "We can not rule out the possibility of large number of people turning up".
"When 2 [million] out of 7.5 million people joined the mass protests, it showed the Hong Kong people deserve democracy", Wong said. Elsewhere, scuffles between students from Hong Kong and China broke out earlier this week at Australia's University of Queensland in Brisbane, with some chanting "free Hong Kong" and carrying signs about Xinjiang detentions while others played the Chinese national anthem and tore up signs. A poster plastered on a lamppost called for an "Investigation on police brutality".
Regional police earlier this week banned more protests from taking place this weekend, but it is understood that organizers plan to convene in the city anyway.
"You should take all necessary precautions to ensure your personal safety", it read.
An investment banker at a USA bank told Reuters he had rescheduled his flight from Hong Kong to Beijing to another day, over concerns flights could be grounded.