Prime Minister Jacinda Ardern will hold audiences with King Charles III and Prince William prior to her attendance at Queen Elizabeth II's funeral.
She will also meet with the United Kingdom's new Prime Minister Liz Truss in a whirlwind schedule ahead of Monday's state funeral.
Speaking to media in London early morning New Zealand time, Ardern said she would "share the sorrow" New Zealand had and pass on deepest condolences to the new King.
"At the end of the day, although this is a period of transition for him, he has also lost his beloved mother ... that's first and foremost for us."
Ardern will first meet with the new King alongside representatives of other realm countries on Sunday [NZT]. She would also hold an audience alongside other international representatives on Monday [NZT].
Yesterday, the acting New Zealand High Commissioner to the UK, Shannon Austin, referenced the King's interest in how the Omicron wave and recent flooding had impacted Kiwis.
Ardern said that showed King Charles III's "genuine love" for New Zealanders and she was confident that would continue.
Ardern's audience with Prince William would take place later tonight [NZT].
Ardern said their meeting would be an opportunity to repay the kindness the new Prince of Wales had offered during New Zealand's times of grief.
Having spent just hours in London, Ardern said the impact of the Queen's death was clear to see.
"This is a nation in mourning and of course, we observed that from New Zealand but being here and seeing it in person, you can just see the sheer scale of this period for the UK and the effect it's had on its people.
"I think the thing that I will never quite understand is how [the Queen] could give her entire life but she did ... to give your entire life, that to me is sacrifice."
Ardern was expected to meet Truss on Monday [NZT], prior to the funeral. She intended to view the Queen lying-in-state over the coming days.
Ardern said she felt "very humbled" and a "great weight of responsibility" representing New Zealand on such an occasion.
Her comments came prior to her attendance at a gathering of various New Zealand Defence Force members involved in the commemorations, including Victoria Cross recipient Willie Apiata, who is one of about 20 New Zealanders invited to Monday's funeral.
Speaking to those gathered, Ardern recalled her memories of speaking with the Queen during lockdown and the late Queen's inquiry about Anzac Day.
Ardern said she pondered how to explain how commemorations occurred during Covid-19 restrictions.
She said she told the Queen how people gathered at the end of their driveways, some listening to the radio.