The eight, stroked by London coxless pair bronze medallist Rebecca Scown, finished second in the world championship final behind the United States to book their trip to the Olympics.
The first five finishers in the final were assured of an Olympic spot. The Dutch were the luckless sixth placegetters on Lake Aiguebelette, France.
"We just stayed within our boat," said crew member Kerri Gowler who, with Grace Prendergast, also took silver in the women's pair. "It is an amazing result. These girls are so positive, it is great to row with them."
Genevieve Behrent, Kelsey Bevan, Ruby Tew, Emma Dyke, Kayla Pratt and coxswain Francie Turner formed the remainder of the crew, coached by Dave Thompson.
The women will be joined by their male counterparts, who finished fourth, 0.13s behind the Netherlands in a race won by Britain with Germany second. Russia also qualified for Rio in fifth.
Stephen Jones, Brook Robertson, Alex Kennedy, Joe Wright, Isaac Grainger, Shaun Kirkham, Michael Brake, Tom Murray and coxswain Caleb Shepherd completed the feat. They are coached by Noel Donaldson.
The men's eight will be New Zealand's first at a Games since 1984.
The joint success has vindicated Rowing New Zealand's decision to push into the big boats, after several years of small boat dominance.
Confidence and belief was gathered when the women finished second and the men third in the final World Cup at Lucerne in July. It suggested they would be in the frame at the worlds and strong displays last night proved that.
The overall results saw New Zealand finish second on the medal table behind Britain, and qualify nine out of a possible 14 boats for Rio.
New Zealand secured nine medals (five gold, three silver and one bronze); Britain had 15 (five gold, nine silver and one bronze) but only hit the top of the table with the men's eight triumph.
Double scullers Eve Macfarlane and Zoe Stevenson kicked off the last block of finals with victory, which for Stevenson meant defending her crown.
It was New Zealand's third Olympic-class gold of the meet, after coxless pair Eric Murray and Hamish Bond, and lightweight double scullers Sophie Mackenzie and Julia Edward 24 hours earlier.
Last year, Stevenson had Fiona Bourke for company. Macfarlane took Bourke's place. It's been tough viewing for Bourke, pushed against her preference into the single sculling seat, but the current duo have proved an outstanding combination.
They won in 6min 45.09s, from fast-finishing Greece, less than a length back, and Germany.
Men's single sculler Mahe Drysdale endured a duel with longstanding Czech rival Ondrej Synek. Synek, who had spent part of the season recovering from injury, pipped the New Zealander by 0.34s.
"Unfortunately I lost the most important race of this year," Drysdale said. "It is a bit disappointing, but obviously next year is the one we all want. I lost because I didn't see Ondrej's move."
Men's double scullers Robbie Manson and Chris Harris hung on in a tight finish for the bronze medal, pipping Germany in the blink of an eye.
Croatia won gold with a splendid performance from brothers Martin and Valent Sinkovic with Lithuania second.
The men's lightweight four finished fourth, squeezed out in a three-way battle for the minor medals with Denmark and France, behind a brilliant Swiss quartet, coached by New Zealander Ian Wright.
