The victim – who has not yet been publicly identified – died in an Auckland hospital on Tuesday night, according to John Tim, a deputy commissioner.
Eight more people have died in hospitals in New Zealand and Australia in the weeks following the eruption, which saw scores hospitalised for severe burns.
Experts say super-heated water that burst from beneath the crater’s surface caused the injuries.
Some victims saw burns cover large portions of their bodies or damage their lungs.
Many of those killed and injured were Australian tourists who had been travelling aboard the Royal Caribbean cruise ship Ovation of the Seas.
Two British women were also hospitalised for injuries.
One of the people who died in the weeks after the eruption was an American woman, Mayuari Singh, whose husband was also wounded.
New Zealand authorities are investigating the circumstances around the disaster.
Many have questioned why tourists were allowed on the island after its alert level was raised by authorities three weeks before the eruption.
Mr Tims, the police deputy commissioner, said the latest victim died at Auckland’s Middlemore Hospital.
Their identity will be revealed once their wider family has been informed, he said.