Independent Kerryn Phelps led a group of politicians and refugee advocates calling for the immediate evacuation of kids on Nauru.
Refugee advocates and politicians plan to deliver a petition to the Prime Minister and Opposition Leader later today to get the remaining refugee children off Nauru.
Eleven children remain on the island and advocates say they plan to hold the federal government to their promise to ensure all kids are evacuated from the island by the year's end.
Independent MP Kerryn Phelps said the issue of giving refuge to detainees on Manus and Nauru is "one of the most important issues facing Australian people at the moment".
Dr Phelps, who was officially sworn in as a member of parliament on Monday, has identified getting the children off Nauru as a key priority since winning the Wentworth by-election in October.
She said she was particularly concerned after talking to medical professionals who have diagnosed the children on Nauru with Traumatic Withdrawal Syndrome.
"Children lose the will to live, they stop eating, speaking, drinking," she told supporters outside Parliament House in Canberra.
"What does the government think will happen when children stop eating and drinking?
"Unless they are brought to Australia and get medical treatment, we will see a death among these children."
She promised to personally deliver a petition with 170,000 signatures to the Prime Minister and Opposition Leader later on Tuesday to get the detainees off Nauru and Manus Island.
'Abomination, black stain on this country'
Independent Andrew Wilkie said it is critical that all detainees on Manus Island and Nauru are brought to Australia and their claims assessed.
"It is an abomination, an absolute abomination and a black stack on this country's name," he said of the country's offshore detention policy implemented over the last five years.
"Australia's response to asylum seekers is illegal under international law and deeply immoral.
"And the fact that a succession of governments have been quite happy to have many children locked up on Nauru in particular...It's a prison island, don't let the government tell you otherwise."
Crossbenchers Derryn Hinch, Rebekha Sharkie, and Greens MP Nick McKim also echoed the call to end the long-term detention of refugees.
'Refugees have hopes and dreams'
World Vision Australia external affairs manager Andrew White thanked Australians for supporting the Kids off Nauru campaign, which was launched in August.
"The tide is turning," he told the crowd.
Mr White said when the campaign started their surveys showed that about 60 per cent of the Australian public were aware people were being detained on Nauru and Manus. In three months, he said, that number has increased to 80 per cent.
To date, 400 community organisations have added their support to the campaign, while 170,000 signatures have been collected on the online petition.
"Since the campaign has started we have been able to humanise refugees and shine a light on the children, their families; and tell their story," he said.
"We have been able to demonstrate that they are not unlike you and I. That they have hopes and dreams and aspirations for a future, for a career, to make a family, to make a home."
'Every child deserves safety'
The crowd also heard from South Sudanese refugee Akuol Garang, who was born in a refugee camp where she stayed for the first 10 years of her life.
"I was forced to live as an adult and have to witness many things children should not have to go through," she said.
"So bombs and suicide and things like that are common memories that children like me - and refugee children like me - experience every single day.
"Those are the memories I live with. And I don't want any child to have to go through the things I went through.
"Now is the right time to get the children out of the camps so they don't suffer," she said.
Refugee turned lawyer Fadak Alfayadh also spoke to the crowd, supporting the call to end the offshore detention of refugees.
She reflected that it was only a quirk of timing that meant she herself was not in detention on Nauru.
"I want the kids on Nauru to be brought here to experience the welcome that I did when I came here 15 years ago," she said.
"[If not for that welcome] I would not have gone on to become a lawyer. I would not have gone on to help people achieve the legal rights and justice they deserve.
"Every child deserves safety."