Tai Mitchell, of Ngati Pikiao and European descent, was born in 1877 at Ōhinemutu, Rotorua. His European father was the surveyor and government land purchase officer Henry Mitchell. The younger Mitchell also trained as a surveyor and worked for the Lands and Survey Department. He soon became a leader in both the Maori and European communities, playing a key role in important hui (gatherings) and public events in Rotorua during the 1920s and 1930s.
With other Maori leaders he devoted much attention to creating scenic reserves in the Rotoiti and Rotoehu areas. In the early 1920s he was chairman of the Te Arawa District Maori Council. In this position he played a key role in dealings between the government and Te Arawa over compensation for lost fishing and other rights in the Rotorua lakes. The settlement, which was never considered by the iwi to be full settlement of their claims, included an annual payment of £6,000 to the Arawa Trust Board, which was to manage the funds for the benefit of Te Arawa.
Mitchell chaired the Trust Board until his death in 1944. Under his leadership the Board carried out a wide range of activities. It purchased land for farming, reopened the Kaituna River mouth, restored pipi beds, awarded educational scholarships and helped maintain marae. Mitchell was a firm supporter of Apirana Ngata's land development schemes, and helped persuade Te Arawa to participate in them. The first scheme involved land at Horohoro, near Rotorua. Tai Mitchell died in 1944.