King Tuheitia's son will be taking over his father's duties for up to 18 months while the king battles diabetes.
A King's Council, known as Te Kaunihera a te Kingi, was also set up over the weekend to help the his eldest son Whatumoana Te Aa Paki in the new role.
A spokesperson for the Kingitanga says Kingi Tuheitia is being treated for a range of complaints, mostly related to diabetes. He is at home, but it is expected that he will not be able to fulfill his duties for the next 18 months.
Whatumoana Te Aa Paki, who is in his early 20s, is no stranger to formal duties. He gave a speech at the unveiling of a new tribal sculpture at the Maori Parliament building in Ngaruawahia at the beginning of June, which marked the start of the Waikato-Tainui hui a iwi (tribal meeting).
The spokesperson says he will be guided by the new council, Te Kaunihera a te Kingi, who include Kingitanga spokesperson and former MP Tukoroirangi Morgan and Northland businessman Sir John Goulter.