New Zealand's ruling Labour Party chose former COVID minister Chris Hipkins on Sunday to replace the charismatic Jacinda Ardern as its new leader, and become the next prime minister of the country.

Hipkins, 44, was the only nomination for the job and his confirmation at a party meeting on Sunday, known as the Labor caucus, was largely a formality.

His appointment to the top job followed the surprise resignation on Thursday by Ardern, who said she had "no more in the tank" to lead the country.

"This is the biggest privilege and biggest responsibility of my life," Hipkins said at a news conference announcing his appointment. "I am energized and excited by the challenge that lies ahead."

Hipkins immediately acknowledged the leadership of Ardern, who he called one of New Zealand's greatest prime ministers and an inspiration to women and girls everywhere.

"She gave voice to those often overlooked in times of challenge and purposefully went about doing politics differently," Hipkins said.

But some of the hate Ardern faced during her term is a reminder that "we've got a way to go to ensure women in leadership receive the same respect as their male counterparts", he added.

Known as "Chippy", Hipkins built a reputation for competence in tackling COVID-19 and was a troubleshooter for Ardern when other cabinet ministers were struggling.

First elected to parliament in 2008, he became a household name fronting the government's response to the pandemic. He was appointed health minister in July 2020 before becoming the COVID response minister at the end of the year.

Hipkins named Carmel Sepuloni as deputy prime minister, New Zealand's first deputy prime minister of Pacific origin.

Sepuloni, 46, is of Samoan, Tongan and New Zealand European descent and lives in Auckland. She holds a number of portfolios, including social development and employment and arts, culture and heritage.

Hipkins said the rest of his team would be announced later.

(Cover: New Zealand Prime Minister Jacinda Ardern (L) and Chris Hipkins arrive at the Labor caucus meeting to elect a new premier at Parliament in Wellington on January 22, 2023. /CFP)