More than 1000 demonstrators marched in Melbourne’s CBD from Birrarung Marr to Parliament House holding Aboriginal flags and banners.
“Off with his head, off with the King,” protesters chanted.
At one point, protesters poured red paint on to the Australian flag, their hands, and the outside of the office of the British consulate.
Protestors cheered as they burned an Australian flag outside the Brisbane British consulate, while others groups of demonstrators shut down parts of the city.
Similar protests occurred in Adelaide and Canberra.
A man was marched out of Government House in Adelaide after holding up a sign and yelling “abolish the monarchy”.
He signed the same phrase in a condolence book inside and has been banned from Government House for 24 hours as a result.
First Nations protestors were communicating that it was their own day of mourning, with them mourning the existence of the monarchy.
One protestor in Melbourne told 9News ”Today is about reflecting on the pain and trauma that the monarchy has bought to our country”, referencing the colonisation of Australia.
“When is anybody going to mourn the deaths that we lost… everybody… my ancestors… who’s mourning that?”
First Nations woman Sarabi Gristwood told 9News in Sydney: “We’ve been asking for a day of mourning since they made January 26 so-called Australia Day. But eight hours after the Queen’s death, they can make this day a day of mourning.”