Prime Minister Bill English says "nobody" expected provisional election results which place National at a strong lead following a record breaking voter turnout.
"The voters have spoken," he said at a bustling National party in Auckland city on Saturday night.
"No one expected that just three weeks ago."
To a cheering audience he thanked Labour leader Jacinda Ardern and congratulated her on a "hard fight".
She had just given her speech at Aotea Centre, acknowledging the result was disappointing.
Provisional results late on Saturday show National has won more seats in parliament than Labour and the Greens combined.
Special votes are yet to be counted - which are expected to boost Labour a percentage point or two - but results on Saturday night indicated National had won 46 per cent of the vote.
But the party still doesn't have enough to govern alone and talks will need to be had, with New Zealand First leader Winston Peters declared the kingmaker early in the evening.
New Zealand First achieved more than 7 per cent of the vote.
"This election campaign has motivated and engaged more New Zealanders than a campaign I can remember," English said.
"A strong economy means the Government can make real change and real progression on New Zealand's challenging, long-term issues.
"Until a new Government is formed we will run a responsible administration abiding by the usual caretaker conventions.
"We don't need to rush this process but equally, with the strong result of the National party with a much larger number of seats...the indication New Zealand has given of support for the direction this country has taken...it's important we are able to move reasonably quickly to form a stable government."
Negotiations with New Zealand First is expected to begin in the next few days.
He thanked National Party president Peter Goodfellow, his deputy Paula Bennett and Finance Minister Steven Joyce, and wife Mary: "For the love....and the determination you shared with over a million New Zealanders tonight.
"To my family who took some part in the campaign, you may have noticed, thank you for your inspiration and your support."