The last time Labour won the party vote was 2002, despite having two MPs in that period.
When asked why he thought people elected him, yet voted for National, Mr Nash said although he was "Labour to the core", people saw him as a pragmatist.
"If it's going to work with Napier I don't care whose policy it is, whose money it comes from whether it's out of a National pot or a Labour pot, if it's going to be good for Napier then I back it."
He had backed moves by National this campaign - including giving funding to social agency Whatever It Takes, and promising to build more housing in Napier - and would hold them to this.
"They came here, they made some promises, we're going to make sure they deliver on those promises now."
This weekend's win also meant he was able to "get that McVicar bogey off my back".
"I certainly heard it a lot, 'you only won because [2014 Conservative Party candidate Garth McVicar] split the vote," he said.
Although their analysis showed Mr Nash would have won in 2014 even without Mr McVicar stealing votes from the National Party candidate, "he said "it's good to finally get rid of that, and prove we've got an overall majority here now".
His victory was praised by former Labour Napier MP Russell Fairbrother, who had no doubt Mr Nash would hold the electorate.
"I think he [proved] himself pretty well in the electorate and I think he's worked really hard at that.
"I didn't see the National Party campaign being very vigorous at all, but I think Stuart won that for what he's done over the last three years rather than the last two months."
Academics have credited the electorate's swing to National with the area's altering boundaries, a move away from industry, the impact of the Maori roll, and a changing demographic.
They have also said that in the case of Napier, if the candidate has a high, local profile, this can influence voters enough to make them toss aside any party loyalty.
Even before becoming MP in 2014 Mr Nash had connections with the city. His National opponent Mr Elliott was a political newcomer who lived outside the electorate - which voters have shown they dislike.
The difference this election is the margins - unlike previous years both the individual and party votes came down to a 4000-vote difference.
Mr Nash won by about 4200 votes, and National's lead over Labour in the party vote came down to just 3580 votes. In 2014 National received nearly double Labour's party votes.
Narrowing this margin was a source of pride for Mr Nash, who said he was very pleased that Labour's party vote had increased from about 21 per cent in 2014, to 36.9.
"It just shows there's a lot of work to do, in this game you can never sit back and rest on your laurels," he said.
Mr Fairbrother attributed the increased Labour party vote to their hard local campaign, and the "Jacindamania" around the election.
"There's a floating portion of that vote there and I think Jacinda certainly appealed to a wide number of people, and I think Stuart has worked really hard. That combination's worked out well."
In his first campaign, National's Mr Elliott said he was glad to have retained his party's hold on Napier.
"We absolutely creamed them on the party vote which is the most important vote. So on the whole you could say job well done there."
He said he took a "very small amount of credit" for the party vote.
"I was happy to go out and reaffirm that the National Party was committed to Napier and would have liked to be a voice inside Government to get Napier what it needs, unfortunately it looks like they'll be in opposition again which is a shame."
He was given credit by Chris Tremain, who in 2005 became Napier's first National MP in more than 50 years.
"He was a new candidate up against a strong local MP with a really good work ethic and the fact that he was able to maintain the party vote majority says a lot about David's hard work."
Although the margin between the two parties had shrunk, Mr Tremain said: "You'd expect from an incumbent MP that they should be an improvement in their party vote over time, and that looks as though that's happened. I think for a new guy to maintain a strong party vote certainly above the national average . . . was a good result for him."
Coming in third was the Green Party's Damon Rusden, who received 1109 votes, and secured 1632 votes for his party - a drop from the 2014 result of 3198.
Mr Rusden said he was pleased overall with his results, and thought the drop in the party vote could have been down to "a very tumultuous election".
"A lot of voters base their politics on how the national campaign is going and our MPs and leaders so that's kind of beyond my control. I did what I could, and the people voted. I got the message out there and it was up to the people I talked to to decide."
He noted that compared with Green candidates standing in other electorates, he had managed to secure more party votes.
