Thousands convened on Gadigal land on Thursday to have their voice heard, stand in solidarity, and oppose the ongoing official decision to "celebrate genocide" on January 26.

The huge crowd filed into Belmore Park in the heart of Eora/Sydney throughout the morning as speakers told stories of more than 200 years of struggle against persecution and colonial violence on their own land.

Impassioned calls to change the date, protect Country, resist brutality, and empower Indigenous people were heard from Elders, community leaders, young mob, and advocates who throughout their lives have risen up for the rights of their people.

"Turn up, show up, rise up" was heard throughout the crowd.

"Always was, always will be.." was echoed in force.

A statement from organisers said the rally called for "the abolition of Australia Day" and will "protest... a continuing war by the Australian state against Aboriginal people and lands".

"(Demands include) return of stolen land, an end to Black deaths in custody and mass incarceration, and abolition of the racist 'child protection' system that continues to steal Black children in record numbers," the statement said.

Gumbaynggirr, Bundjalung and Dunghutti activist Lizzie Jarrett made the significance known of where those coming together stood.

"Australia Day is dead," she said. "We don't celebrate genocide."

"Where we stand today is ground zero of a genocide of First Nations people, land, waters and the future. Are you here to help us change this shit or what?

"As much as I love being here with you mob today, I pray for one day that me and our little babies don't have to stand here and tell you what to do to make our lives better."

Uncle David Bell led a rousing acknowledgement of Country, paying respects to the Gadigal people and all clans and nations across the continent.

Activist and Greens' NSW upper house candidate Lynda-June Coe was welcomed to the microphone to impart some "grassroots education".

Steadfast in saying it's time for a change, Ms Coe said after 235 years, "we ain't going nowhere".

"They tried to wipe us out. (We're) still here," she said.

"They tried to breed us out. Still here. They tried to commit genocide on us. Still here.

"What you see this morning people, with the welcoming of ceremony, is the continuation of Aboriginal sovereignty that's, best believe, still here."

Reminders of the unlawful attack of Indigenous sovereignty were a powerful message.

That attack was said to extend to ongoing land rights disputes and environmental threats.

17-year-old Wiradjuri student, activist and advocate Ethan Lyons led a plea for fracking to end across the country.

Relatives of David Dungay jr, a 26-year-old man who died in police custody in 2015, expressed the need for action and culpability for the hundreds of Indigenous deaths in custody which continue to cause pain.

Questions were raised on the merits of a change to enshrine a Voice in a constitution which, by some, has never been recognised.

"We don't want any Voice. We are the voice," Ms Jarrett said.

A press release from rally organisers labelled the Voice as proposed a "powerless advisory body" and called for "Sovereignty before Voice".

Malyangapa and Barkindji rapper Barkaa performed her song I cant Breathe.

Following speeches a peaceful march was led through the streets as a wash of people, messaging and chants spread over the streets in Sydney's inner-city.

Invasion day protests were carried out in major cities and towns throughout the country.