Mahuta was adopted by King Koroki, head of the Maori King movement, and raised near Huntly. His adoptive sister is Queen Te Arikinui Dame Te Atairangikaahu.
He left school at 15 without qualifications and entered the army, followed by laboring jobs. Then he decided to complete his education and eventually earned an MA in anthropology and became head of Maori Studies at Waikato University. His work towards a PhD was cut short by a call from his tribe to lead the prosecution of their claims for the return of lands illegally confiscated by the NZ government in the 19th century and he helped broker a settlement in 1995.
He was knighted for his work.
He suffered from diabetes in later years.