Supporters of the law have said Hong Kong courts will have the final say over whether to grant such requests, and suspects accused of political and religious crimes will not be sent to mainland China for a trial.
After weeks of growing local and worldwide pressure, the protest is expected to reflect the broad range of opposition to the bill, with many saying they simply can not trust China's court system or its security apparatus.
Concerns have spread from Hong Kong's democratic and human rights groups to secondary school students, church groups and media lobbies as well as corporate lawyers and pro-establishment business figures, some usually loathe to contradict the government.
One protester held a sign reading "Carry off Carrie", while another declared "Extradite yourself, Carrie".
"The Australian government is taking a close interest in the proposed amendments to the Fugitive Offenders Ordinance in Hong Kong, including to ascertain any impacts on Australian residents", the spokesperson said via email.
If the law is implemented anyone can disappear from Hong Kong.
But there is widespread concern about the broader implication of the proposed law for Hong Kong, a former British colony that was returned to China in 1997 but has maintained its own legal and political system for 50 years.
Protesters shouted "protect Hong Kong" and chanted "no China extradition, no evil law", calling for Hong Kong's chief executive Carrie Lam to step down.
The crowd on Sunday included young families pushing babies in prams as well as the elderly braving 32 degrees Celsius heat. Taiwan has already said it won't seek extradition if the bill is passed.
Insurance agents, executives and small entrepreneurs joined bus drivers and mechanics, with Reuters speaking to dozens of people saying it was their first protest march.
"There are 1,030,000 people at today's march", an organiser told crowds gathered outside the city's legislature, prompting a cacophony of cheers and applause.
"I come here to fight", said a wheelchair-bound, 78-year-old man surnamed Lai, who was among the first to arrive.
The latest proposal has come after a 19-year-old Hong Kong man allegedly murdered his 20-year-old pregnant girlfriend while they were holidaying in Taiwan together in February last year.
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Fernandes, 24, has had a fantastic season in terms of goal returns, with 32 goals and 18 assists from midfield in just 53 appearances.
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For dessert, there were lighter options as well with the inclusion of raspberries, blueberries and red currant. Pratt was previously married to Anna Faris , which ended after nine years in 2017 when they filed for divorce.
"I need to save my daughter".
Officials in Hong Kong are expected to bring the proposed law to parliament on Wednesday.
Critics fear the extradition bill would allow Beijing to round up critics that live in or transit through Hong Kong, threatening the city's judicial independence and further eroding its democratic freedoms.
Sunday protests were also being planned in 25 cities globally, including London, Sydney, New York and Chicago.
"It's a proposal, or a set of proposals, which strike a awful blow ... against the rule of law, against Hong Kong's stability and security, against Hong Kong's position as a great worldwide trading hub", the territory's last British governor, Chris Patten, said on Thursday.
Opponents of the bill question the fairness and transparency of the Chinese court system and worry about Chinese security forces contriving charges.
"Until the Chinese government is able to prove to us that its criminal justice system does not arbitrarily detain individuals, that there are fair and transparent judges, that the use of torture is not endemic... until all of these assurances are met, Hong Kong can not in good faith extradite individuals to China", Ms Fast said.
Foreign governments, including the USA, have criticized the bill for fear it would impact Hong Kong's rule of law and financial markets, according to Reuters.
Concerns were highlighted on Saturday with news that a local high court judge had been reprimanded by the chief justice after his signature appeared on a public petition against the bill.
Human rights groups have said that China's justice system has a record of arbitrary detention, torture and violations of fair trial rights. "AmCham has serious reservations about the Hong Kong extradition bill", Tara Joseph, the president of AmCham in Hong Kong, told TIME.
They also say safeguards will be adequate, although protestors disagree.
"We continue to listen to a wide cross-section of views and opinions and remain to open to suggestions on ways to improve the new regime", a government official said on Sunday.