Race 10 on Course A in Auckland's Waitemata Harbour got under way at 4.45pm today after the start was postponed by 30 minutes.
The Kiwis in the faster boat, Te Rehutai, won the 36th America's Cup, beating Luna Rossa 7-3 in the best-of-13 series with a dominant 46-second victory.
Emirates Team New Zealand retained the 'Auld Mug', international sport's oldest trophy, four years after beating Oracle Team USA 7-1 at the 2017 match in Bermuda.
It was their fourth America's Cup triumph after winning in 1995, 2000 and 2017.
"It's unreal. Seeing all the people involved over three-four years, how many Kiwis out here supporting the campaign -- messages from everyone, from the Prime Minister to high school kids, it means the world to us," said Team NZ's helmsman Peter Burling.
"We're blown away by what we've achieved as a group."
New Zealand Prime Minister Jacinda Ardern said they had made the country proud.
"Team New Zealand has once again made us all so proud by retaining the America’s Cup as New Zealand’s cup,” Ardern said in a statement.
"We want to see it all over again in 2023. The Government has already agreed that the successful America’s Cup team will be supported to stay together while it plans its next defence of the Auld Mug."
Italy's hopes of winning sailing's showpiece event were dashed again in the nation's third America's Cup match, having lost 5-0 to Team New Zealand in 2000 and 4-1 to the United States in 1992.
"Fantastic experience, (we) want to congratulate TNZ have done a fantastic job," said Luna Rossa co-helmsman Francesco Bruni.
"Also have to congratulate Luna Rossa, we proved to the world that we could do it and yeah, it was hard luck in the last couple of days but we did a great job as a team."
"Pete, if you can hear me, congrats, mate, to you and the whole team.
"Full credit to Team New Zealand... they developed a fantastic package and deservedly champions. We need to go have a beer with the Kiwis," the Australian said.
NO MISTAKES
After fierce sailing in race nine on Tuesday, the decider ended up a procession for the home yacht as Team New Zealand's superior speed left the Italians praying for a mistake from the Kiwis.
There was no late twist, however, as Team New Zealand rounded the final gate 49 seconds before the challenger and crossed the line to cheers from home fans on spectator boats and crowded on the foreshore.
The team pumped fists and embraced on the yacht as Burling sprayed his crew mates with Champagne.
It was Team New Zealand's fifth straight race win, having come back from 3-2 down after race five.
It proved a master-stroke as they carved out an early lead after the first mark and extended it to nine seconds coming into the third leg.
Luna Rossa had a poor exit from the second gate and Team New Zealand's lead blew out to 27 seconds to leave the Italians hoping for a mistake from the Kiwis.
But the home yacht named 'Te Rehutai' was four-five knots quicker on the downwind legs and enjoyed stable breezes to the finish.
"We got better and better every race and today just showed the speed of the boat, sailed nicely and great way to end it," said Team New Zealand flight controller Blair Tuke.
"Really happy to get a good start, we were on the right side of the race track.
"From there we never really gave them a chance."