Wellington, New Zealand – In a political shock for New Zealand, the country's hugely popular Prime Minister Jacinda Ardern on Thursday announced she will step down from the role by February 7.

Ardern made the surprise announcement during her first press conference of 2023.

"Being prime minister has been the greatest honor of my life and I want to thank New Zealanders for the enormous privilege of leading the country for the last five and a half years," Ardern said through tears.

"With holding such a privileged role comes responsibility, including the responsibility to know when you're the right person to lead, and also when you're not," the 42-year-old said.

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She said the role had taken "a lot" out of her.

"You cannot and should not do the job unless you have a full tank, plus a bit in reserve for those unplanned and unexpected challenges that inevitably come along."

Ardern said as well as long-term issues like housing, child poverty, and climate change, she had also had to respond to a far-right terror attack, volcanic eruption, the pandemic, and the ensuing economic crisis.

"The decisions that had to be made have been constant and weighty," she said.

"I know what this job takes, and I know that I no longer have enough in the tank to do it justice. It is that simple," the prime minister added.

"As to my time in the job, I hope I leave New Zealanders with a belief that you can be kind, but strong, empathetic but decisive, optimistic but focused. And that you can be your own kind of leader - one who knows when it's time to go."

Elected prime minister in 2017 at 37-years-old, Ardern is one of the world's youngest female heads of government, and only the second to become a mother while still in office.

In February 2017 she became a lawmaker in a by-election, and within a month she was elected as deputy leader of Labour.

She was then made leader in August, taking on the task of overturning a National government that had been in power for nine years.

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During coalition negotiations in 2017, Ardern and partner Clarke Gayford found out she was pregnant.

Just six days later, New Zealand First leader Winston Peters announced he would form a government with Labour, making Ardern prime minister.

Her rise from deputy leader of the opposition party to prime minister was so meteoric that it earned a proper name, Jacindamania.

In June 2018, Ardern and Gayford welcomed their baby Neve Te Aroha to the world, with Ardern taking six weeks of maternity leave.

Her resignation will take effect on the appointment of a new prime minister. A caucus vote to elect a new Labour Party leader will take place on Sunday.