Labour's Jacinda Ardern will take on the Green Party's Julie Anne Genter in the upcoming Mt Albert by-election.
Both MPs were confirmed on Thursday as their party's respective candidates while National will not contest the by-election, which will take place on February 25.
Ms Ardern was the only person to put her hand up for Labour.
The seat was left vacant by former leader David Shearer, who left the party for a United Nations job in South Sudan.
In December, Ms Ardern confirmed she wanted to stand for the staunchly Labour seat, once held by former Prime Minister Helen Clark.
On Thursday afternoon, Labour General Secretary Andrew Kirton confirmed the decision and Ms Ardern will be officially named at a special meeting with local member on January 22, as per the party's internal process.
"We're really looking forward to talking to locals in Mt Albert about the National Party's dismal record on housing, health, and transport," Mr Kirton said.
"It's just a shame that National isn't prepared to front up to the Mt Albert community and explain their record."
Meanwhile, Ms Genter, the Greens' Auckland Issues and Transport spokesperson, says the by-election will give voters a glimpse of a Labour-Green government and insists the campaign will be a positive one.
Both parties have a memorandum of understanding to work together to change the Government in this year's election.
"New Zealanders have a big choice to make in 2017 - to stick with the status quo, or to change the Government to get real action on things like affordable housing, public transport, and protecting our rivers," Ms Genter says.
"Labour and Greens share a vision for a fairer New Zealand - affordable housing and healthy kids. Whichever of us Mt Albert vote for, they will get a competent, experienced MP committed to a fairer New Zealand."
Mana also plans to contest the by-election.
In one of his first decisions as Prime Minister, Bill English decided not to stand a candidate.
"We don't intend to participate in a by-election in the new year that is in a safe Labour seat," said Mr English.
"The National Government is focused on winning the 2017 General Election later in the year."
The party's previous candidate, Melissa Lee, lost to Mr Shearer, though National won the party vote in the 2014 election.
Ms Ardern has twice contested the Auckland Central electorate against National's Nikki Kaye, narrowly losing both times.