Jacinda Ardern was officially replaced on Wednesday as New Zealand prime minister, after stunning the country by announcing her abrupt departure from the role last week.
New Prime Minister Chris Hipkins, 44, was sworn in by New Zealand's governor-general during a ceremony in the capital, Wellington.
"This is the biggest privilege and responsibility of my life," Hipkins said after formally taking office.
"I'm energized and excited by the challenges ahead."
Ardern said last week she no longer had "enough in the tank" after steering the country through natural disasters, its worst-ever terror attack and the Covid-19 pandemic.
She made her last public appearance as prime minister earlier on Wednesday, walking out of the distinctive Beehive parliament building as hundreds of onlookers broke into a spontaneous round of applause.
Prince William was among the first to congratulate Ardern, who became a global figurehead of progressive politics during her five years in charge.
"Thank you Jacinda Ardern for your friendship, leadership and support over the years, not least at the time of my grandmother's death," he wrote on his official Twitter account.
Folk singer Yusuf "Cat" Stevens, who played a concert in memory of the 51 people killed during the 2019 Christ church mosque massacre, also praised Ardern.
He said on Twitter that Ardern "kept New Zealanders together following the terror attack in Christchurch".
But Ardern on Tuesday said she would "hate" for her departure to be seen as "a negative commentary on New Zealand".
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