More than 2000 Sydneysiders answered a national call to rally on Sunday in support of refugees and push for an end to mandatory detention.
In Melbourne more than 3000 activists came together. There were also rallies in Brisbane, Canberra and Perth.
"We wanted to send a very clear message to Malcolm Turnbull that the refugee movement hasn't gone away," the Refugee Action Coalition's Ian Rintoul told AAP.
The main focus was closing the Manus Island and Nauru detention centre, but those at the rally also hoped the government would repeal the Border Force Act.
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Many in attendance were motivated to speak up by the story of a pregnant Somali refugee who was raped on Nauru, Mr Rintoul said.
Greens senator Lee Rhiannon and Syrian refugee Abdul Hakim were among those who spoke to Sydney crowds who waved banners reading "welcome refugees from Syria" and "Close Manus. Close Nauru. Welcome refugees".
A large crowd, including unions and various social and political groups, gathered at Sydney's Town Hall on Sunday afternoon before marching to Belmore Park.
Police were on patrol but there were no signs of trouble at either of the major rallies.
