The teams had shared two tournament wins between them and the exciting final victory was set up by tries to Carla Hohepa either side of halftime.
Australia scored first through Emilee Cherry and still led 5-0 after seven minutes before Shiray Tane, Kayla McAlister and Hohepa pushed New Zealand 17-5 clear at halftime.
Hohepa widened the gap soon after the break before Ellia Green responded for Australia to leave them 22-12 going into the final five minutes.
McAlister’s second try near the end sealed the result and made it two-from-two for New Zealand in the women’s series, adding to the men’s crown secured by the All Blacks sevens team a week earlier.
Canada were third ahead of England after beating the same side 10-0 in the third place playoff.
Australia gained some consolation when the speedy Cherry was named player of the year, having topped the series tryscoring list with 33.
New Zealand had arrived in Amsterdam with a two-point lead in the standings over Australia and a significantly better point differential, meaning the title was theirs regardless of the outcome of the final unless they lost by over 74 points.
Both teams were untroubled in reaching the final.
New Zealand beat Russia 36-0 in the quarter-finals and England 26-10 in the semis while Australia accounted for Brazil 33-0 and then Canada 17-0 in their pathway.
New Zealand finished four points ahead of their trans-Tasman rivals in the standings, having also won tournaments in Atlanta and Guangzhou.