Relief spread across the city as anti-government protests ended relatively peacefully on Saturday, with no tear gas fired, the South China Morning Post reported.
Sunday's protest organiser, the Civil Human Rights Front, had applied to the police for a march from Causeway Bay to Central.
But police only allowed a rally within Victoria Park, saying the front could not ensure public safety given violence at recent protests.
The organisers have estimated that the rally will be attended by more than 100,000 people.
Reading out the rally declaration amid heavy rain, Civil Human Rights Front convenor Jimmy Sham said that while protesters have pressurised the government into suspending the now-shelved extradition bill, which would would have allowed criminal suspects to be sent to mainland China, the city police were carrying out Chinese-government-style suppression.
He criticised the police for firing tear gas, rubber bullets and beanbag rounds on the protesters and even near elderly-care homes.
"The people of Hong Kong are outraged at the government and police," he said, adding their says fight will not be over even after Sunday's rally ends.
Mass protests erupted in June over the Hong Kong government's now-shelved extradition bill, the South China Morning Post reported.
The administration dropped the draft legislation on June 15, with city leader Carrie Lam later declaring it dead.
Since then protesters have escalated their campaign with street demonstrations and non-cooperative action, some of which have turned violent through clashes with police and those loyal to the government.
( With inputs from IANS )