US President Donald Trump once called the deal, which was agreed under his predecessor, "dumb".
The agreement allows for up to 1,250 asylum seekers to Australia to resettle in the US.
In return, Mr Turnbull's administration has agreed to resettle people from Guatemala, Honduras and El Salvador who have sought asylum in the US.
The deal would be honoured but not necessarily admired, visiting Vice-President Mike Pence said after talks with Australian PM Malcolm Turnbull.
