Queen Elizabeth's death will be recognised in New Zealand with a national period of mourning and a memorial service.
New Zealand has a detailed plan in the event of the head of state's death, which is now under way.
The Prime Minister and Governor-General were first informed, along with the Ministry of Foreign Affairs and Trade and the Department of Internal Affairs.
King Charles' succession has occurred immediately and automatically. Princes Charles, as first in line to the throne, is now King of New Zealand and New Zealand's head of state.
No formal action is required by New Zealand authorities. Under New Zealand law, all functions and powers of the Crown automatically transfer to the Queen's successor.
Prime Minister Jacinda Ardern said today that the Queen was an "incredible woman" who had continued working right until the end.
"The Queen has been such a constant in our lives," she told reporters at a press conference in the Beehive.
Ardern had discovered the Queen had died when she was woken by a police officer shining a torch into her room at 4.50am today.
One of her abiding memories of the monarch was her laughter.
"She was extraordinary," Ardern said.
New Zealand would now move into a state of national mourning.
This will continue until after a New Zealand State Memorial Service, which is expected to be around the tenth day following her death.
"The New Zealand flag will be flown at half-mast from the announcement of the death up to and including the day of the funeral, except on Proclamation Day – the day the new Sovereign is announced officially when flags are to be flown from the top of the mast."
Condolence books will likely be opened at Parliament and the National Library, as they were following the death of Prince Philip , and by local councils around the country.
There will be gun salutes as appropriate.
Places will be designated for members of the public to leave flowers.
New Zealanders will receive full information and updates at the time via the Governor-General's website.
The death of the Queen has no impact on any other part of New Zealand law. All references to the Sovereign in documents or instruments already in force include a reference to her heir or successors.
New Zealanders will have opportunities to pay their respects to Queen Elizabeth in the coming days. It is understood several events are planned, with finer details to be decided by the Prime Minister.
A period of national mourning begins immediately after the announcement of the Queen's death and will continue until a planned state memorial service in New Zealand.
The service is likely to be held at the Wellington Cathedral of St Paul's, and will take place after the funeral service in the United Kingdom. The content of the service is a matter for the Prime Minister.
There are expected to be condolence books at Parliament and the National Library, as they were after the death of Prince Philip in 2021. Local councils around the country will also have condolence books.
It is understood there will also be gun salutes by the New Zealand Defence Force, and places will be designated for mourners to leave flowers.
A proclamation ceremony will take place in the next day or two to officially recognise the accession of the new King.
In 1952, when Queen Elizabeth succeeded King George VI, the proclamation was read aloud on the steps of Parliament by Governor-General Bernard Freyberg, alongside the Acting Prime Minister and in front of a crowd.
Lord Freyberg proclaimed "the High and Mighty Princess Elizabeth Alexandra Mary to be Queen Elizabeth the Second, by the grace of God, Queen of this Realm and of all her other realms and territories, Head of the Commonwealth, defender of the faith".
The New Zealand flag will be flown at half-mast at public sites until the New Zealand state memorial service. It will be temporarily flown at the top of the mast on Proclamation Day.
National Party leader Christopher Luxon said the Queen's death ended a "remarkable reign and a lifetime of service".
"On the recent occasion of The Queen's 70th Jubilee, I said that her unflinching dignity, compassion, and selflessness had given the Commonwealth a sense of security throughout her reign.
"The strength and stability of Her Majesty's leadership of the Commonwealth was a reassuring anchor for New Zealand and New Zealanders in uncertain and changing times.
"Through both the tumultuous and the good, her dedicated service embodied the values of duty, commitment, and strength.
"I send my condolences to her family, who will also be mourning the loss of a beloved mother, grandmother, and great-grandmother, including to our new head of state, King Charles III."