No more asylum seeker children will be held on Nauru with the final four preparing to fly to the US with their families for resettlement.
They are the last of the more than 200 children who had been held at the island's processing centre when the coalition won government in 2013, marking a milestone for the Morrison government.
Prime Minister Scott Morrison said on Sunday it was vindication of the coalition's Operation Sovereign Borders policy.
When he took over as leader at the end of August, there were 109 children in immigration detention on Nauru.
"Since then, and as was made clear at the time, we have been working quietly and methodically through this process without compromising the integrity of Operation Sovereign Borders," Mr Morrison said in a joint statement with Immigration Minister David Coleman.
"We have got all the children Labor put in detention centres out, and we have shut down all the detention centres Labor opened, including on Christmas Island."
Opposition Leader Bill Shorten welcomed the news while querying whether the government should really be taking all the credit.
"I do believe if the crossbench and the opposition and some of the progressive Liberals hadn't pursued this, I do wonder if the children would have been off," he told ABC TV's Insiders on Sunday.
Greens leader Richard di Natale said it was long overdue for those children.
"They've been languishing there for years and years," he told Sky News' David Speers Sunday program.
"These are kids that will have years of counselling ahead of them."
Asylum seeker advocates, including the Human Rights Law Centre, the Asylum Seeker Resource Centre, the National Justice Project and Maurice Blackburn Lawyers also applauded the move but warned there was a continuing medical crisis for those adults remaining in immigration detention on Nauru and Manus Island.
With the resumption of parliament in a fortnight, Labor and crossbenchers are expected to push a bill that gives doctors more say in whether refugees in offshore detention should be moved to the mainland for medical treatment.
More than 1000 asylum seekers remain in the two centres and continue to face an uncertain fate.
Mr Shorten said Labor would continue to pursue the laws around access to medical treatment but did not know whether all the crossbenchers still backed the move.
"It really depends what sort of pressure the government has brought on the crossbenchers," he said.
DETENTION NUMBERS WHEN THE COALITION CAME TO POWER IN 2013:
- 50,000 asylum seekers arrived on 800 boats under Labor
- 1200 died at sea trying to reach Australia
- 2450 asylum seekers on Manus Island and Nauru at the peak in mid-2014
- Now a little over 1000 remain
- 220 children held offshore and 1992 children on Australian mainland in 2013; the figure is now zero
- 19 detention centres, including Christmas Island facility, closed by the coalition government.