Labour leader Jacinda Ardern has been rewarded by voters with a landslide win — delivering her power in her own right, and an absolute drubbing to the National Party.

Labour has almost 50 per cent of the vote — the most any party has achieved under MMP and easily enough to govern without relying on another party, meaning it will get more than the 61 seats needed for a parliamentary majority.

However, the night was an absolute bloodbath for Judith Collins' National Party — and Labour's former coalition partner NZ First was kicked out of Parliament. It came in well under 30 per cent — a result that would give it about 35 seats. That is 20 fewer than the last election.

Ardern arrived at the Auckland Town Hall to scenes of jubilation and was joined on the stage by her partner Clarke Gayford and fellow Labour MPs.

"Tonight New Zealand has shown the Labour Party its greatest support in at least 50 years," she told supporters.

She acknowledged voters who had switched allegiances from National.

"For those amongst you who may not have supported Labour before... to you I say thank you. We will not take your support for granted."

She said Labour would be a party which works for "every New Zealander".

The Green Party got nearly 8 per cent of the vote, and MP Chloe Swarbrick pulled off a major upset by winning the coveted seat of Auckland Central.

The 26-year-old becomes only the second Green MP to win an electorate seat - 21 years after party co-leader Jeanette Fitzsimons won the Coromandel seat, which she held for just one term.

The Māori Party is poised to return to Parliament with Rawiri Waititi about to wrest the Waiariki seat off Labour's Tāmati Coffey.

Act romped home with 8 per cent of the vote and David Seymour is set to get about 10 MPs into Parliament.