Bryce Barker, who now lives in Australia, was detained along with other members of his investigative team.
They were doing fieldwork in a remote part of the highlands of PNG when they were taken by a criminal gang from Hela province who demanded a ransom for their freedom.
Their release ends days of negotiations and a complex security operation involving PNG police and defense personnel, in coordination with the Australian and New Zealand governments.
It is unknown if any ransom was paid.
It comes two days after another woman who was also taken was released.
Foreign Minister Nanaia Mahuta praised the release on Twitter and welcomed their safe return.
PNG Prime Minister James Marape announced the release of the hostages on Facebook and thanked police and defense, local leaders and the community for their help.
“We apologize to the families of those held hostage for ransom. It has taken a while, but the last three have been successfully returned through covert operations,” he wrote.
“For criminals there is no profit in crime. We thank God that life was protected.”
Another New Zealander, pilot Phillip Mehrtens, is apparently still in captivity with separatist rebels after landing a plane in the remote highlands of Papua.
There is no new information on whether or not he will be released.