The Duke and Duchess of Cambridge were guests of Governor-General Sir Jerry Mateparae and his wife Lady Janine at the reception for 200 where some of New Zealand's finest foods were showcased and the Prince unveiled a new portrait of his grandmother, the Queen.
Prince William's speech began with a Maori greeting, and he got a loud "kia ora" in response.
"No insults yet," he quipped to laughter from the audience.
He thanked the Governor-General for having him and the Duchess to stay.
"I hope George doesn't keep you up. He can be very vocal at 3am. I swear I heard him doing the haka this morning. He's a bonny lad and I'm fairly sure he will be a prop forward," he said.
Prince William said he was certain Catherine would leave with the same affection for New Zealand as he had.
He said it was an innovative country.
"New Zealand repeatedly demonstrates its progressiveness."
He said being the first country to give women the vote was an early sign of that.
He said that was combined with a beautiful landscape, and some "very nice wine as well."
Kate again stunned with her wardrobe, wearing a Jenny Packham bespoke dress, black with fern hand-stitched beading on the shoulders to reflect the NZ theme.
She stood alongside her husband as he unveiled the portrait of the Queen.
The painting, by New Zealand artist Nick Cuthell, was commissioned for the New Zealand Portrait Gallery.
The Queen is depicted in a simple blue day dress and wearing the silver fern brooch she has loaned to the Duchess of Cambridge for her New Zealand tour.
Prince William said New Zealanders' "fondness for my grandmother the Queen" was what struck struck him most, before before unveiling the portrait.
The portrait will be hung as part of the permanent collection in the gallery's home in Shed 11 on Queen's Wharf in Wellington.
Before the reception began, the couple went down a line, greeting the guests who included Prime Minister John Key, Labour leader David Cunliffe, Speaker David Carter and Maori Party leader Te Ururoa Flavell.
Sir Jerry greeted the royals, saying it was special to have them in the country.
"We are absolutely delighted - all of us - to have you here. However, the greatest prestige goes to Prince George."
The Duke and Duchess moved through the crowd, where the guests had been arranged into small groups for their allocated time with the royals.
Prince William spoke to Green MPs Kennedy Graham, Gareth Hughes and Steffan Browning, although party co-leaders Russel Norman and Metiria Turei were not at the reception.
New Zealand's finest produce was the order of the day at the reception.
The royals and esteemed guest - mainly MPs, judges, diplomats and military personnel - dined on canapes which included locally made Zany Zeus feta, potted Lake Taupo trout, braised Cardrona and Merino lamb tarts and Waikanae crab toasts.
Earlier, Prince William held meetings with both Mr Key and Mr Cunliffe, although what they spoke about on a formal level was off limits.
Prince William told Mr Key he expected his race against Catherine on the America's Cup boats in Auckland tomorrow to be "a bit of healthy competition."
The Prince greeted the Prime Minister warmly after Mr Key said it was good to have him back in New Zealand.
"It's good to be back. Thank you for having me," the Duke of Cambridge told him
Mr Key said the weather was expected to be a bit better in Auckland and in Queenstown next week.
Prince William said it would be "just my luck" if the Americas Cup race had to be abandoned because of the weather. He said he had been telling everyone he would win it, and laughed when Mr Key asked if it was a bit of competition.
"A bit of healthy competition, yes."
He also indicated he was looking forward to the wine-tasting the royals will have in Queenstown: "We drove through the vineyards [ in Marlborough] today and I was getting quite thirsty."
Prince William asked Mr Cunliffe how he had enjoyed the visit to Blenheim today before saying going there had been "poignant for me" as an RAF pilot.
He had enjoyed the visit to the Omaka Aviation Heritage Centre.
"The whole museum is incredible. It's so important to keep the linkage of the generations."
Mr Cunliffe gave him a silver and black plaque with koru fern fronds on it and explained the meaning of the symbol, saying it meant renewal and nurturing.
The Prince said it was "super" and he liked the colour scheme.
Mr Cunliffe said it resembled the skies since he had arrived, prompting a smile from the Prince.
"We haven't had done so well with the weather," he said.
