Due to their failure to make the top three at their World League event in Argentina several weeks ago, combined with Brazil's men succeeding in taking an Olympic place, they must beat world No 1 Australia in the Oceania Cup in Stratford over Labour weekend. That would guarantee a trip to Rio.
They did topple Australia, on a penalty shootout at April's Azlan Shah Cup in Malaysia. They may also be hoping as Australia have already qualified their guard might be down in Stratford.
But the men know they slipped up badly at the World Cup in June, losing a marathon shootout to Canada in a game they should have won; then losing to Spain, also ranked several places lower in their final game of the event.
Hockey New Zealand high performance director Terry Evans was delighted with the news on the women from the International Hockey Federation.
"Although we were confident we had done enough through the qualification process, until it was official there was always a level of concern," he said. "This is an exciting time for the women, but none of us are under any illusion as to the hard work needed if we are to be successful in Rio.
"Now that we have confirmation of our qualification, we have 12 months to prepare and that will come and go very quickly."
With eight teams now confirmed to compete in Rio, the remaining four will be decided through the remaining continental qualifiers, the Pan Am Games, Euro championships, Africa Cup and Oceania Cup.
If a team who has already qualified for the Olympics - say Australia's men - win any of the continental qualifiers, the extra spot goes to the next highest ranked finisher from the World League semifinals. Canada and Spain, yet to be confirmed in the Olympic field, both finished ahead of New Zealand at that event.