Richard Marles and Foreign Minister Penny Wong are among the cabinet ministers travelling to Port Moresby for the Australia-Papua New Guinea ministerial forum.
The trip coincides with Beijing's second in command Premier Li Qiang ending his four-day visit of Australia on Tuesday.
Senator Wong earlier described the visit as a "very substantial and serious" ministerial delegation that showed Australia was committed to engaging the Pacific region on climate change and broader security issues.
"It is because this government understands the importance to Australia of the engagement in the Pacific," Wong said on Sunday.
She also took a swipe at the coalition for what she said was "leaving the field" in the Pacific region during their time in power until 2022.
The talks in PNG will be co-chaired by Senator Wong and her PNG counterpart Justin Tkatchenko.
The foreign minister visited the Solomon Islands earlier in June within weeks of Mr Marles for talks with the country's new prime minister, Jeremiah Manele.
Pacific Minister Pat Conroy, Agriculture Minister Murray Watt and Home Affairs Minister Clare O'Neil will also attend.
The delegation will also meet representatives from businesses.
Mr Marles described PNG as one of Australia's closest and most important defence partners.
"I am delighted to return to Papua New Guinea to discuss how we can work even more closely together to address the security and defence challenges facing our region," he said.
Attorney-General Mark Dreyfus announced Australia had donated a police boat to the Royal Papua New Guinea Constabulary (RPNGC) for border patrols of the Torres Strait region.
Police Patrol Vessel Minigulai was bought by the Australian Federal Police from the Tasmanian force for $1.8 million, and will train up PNG's police to crew the vessel.
"It's far and away the biggest boat that the RPNGC has ever had and it will enable a great deal of expeditionary work, access to much more remote parts of the many islands that they cover in Papua New Guinea," Mr Dreyfus told reporters in Port Moresby.
"Australia is very pleased to assist our friends."
