Kīngi Tuheitia has died, aged 69, just days after celebrating the 18th anniversary of his coronation.
A statement issued by the office of the Kiingitanga said Tuheitia had been in hospital recovering from heart surgery.
He died "peacefully" on Friday morning, surrounded by his wife Makau Ariki and their children Whatumoana, Korotangi and Ngawai Hono I Te Po, the statement said.
"The death of Kiingi Tuheitia is a moment of great sadness for followers of Te Kiingitanga, Maaoridom and the entire nation."
Tuheitia was expected to lie in state at Turangawaewae Marae for five days.
He would then be taken to his final resting place on Taupiri Mountain, the statement said.
Tuheitia Pōtatau Te Wherowhero VII was born Tuheitia Paki in 1955 in Huntly and educated in Waikato and Auckland.
He was crowned on 21 August 2006 following the death of his mother, Te Arikinui Dame Te Atairangikaahu.
He has been at the forefront of Māori issues and represented the Kiingitanga at a number of events over the years, including the funeral of King Taufa'ahau Tupou IV of Tonga in 2006 and the coronation of King Charles III and Queen Camilla in London in 2023.
In 2019, he met with Pope Francis at the Vatican.
The kīngi was also the patron of several organisations, including the kapa haka competition Te Matatini.