Lotto spokeswoman Emilia Mazur said the man had heard about the unclaimed prize, but hadn't given it a second thought until coming across his ticket.
"He quickly saw that he had six winning Lotto numbers on one line, and the all-important Powerball number," Ms Mazur said.
The couple are still deciding what to do with the winnings.
"They were quite shell-shocked when they realised just how much they'd won. They are slowly coming to terms with the fact that they are now millionaires - a few times over - and are enjoying some exciting conversations about all the things they can do with their winnings."
It's the biggest Lotto prize ever claimed in Ohakune. The previous biggest was $1 million, from the Winning Wheel.