Huiatahi Barrett was born at Waiharakeke, Kāwhia, probably in 1873 or 1874. His grandfather was an Englishman, Nathaniel Barrett, who arrived in New Zealand in the 1840s. He worked as a teacher in the Kāwhia district, later supplementing his income with small-scale farming. In 1849 he married Caroline Te Maawe Newha of Ngāti Maniapoto; Huiatahi's father, Thomas Te Murunga Barrett, was born in 1852. He and his six siblings were raised in their mother's extended family at Waiharakeke. On reaching adolescence, Thomas went to Taranaki to avoid the hostilities in the Waikato district and to work as a farm labourer and farrier. He returned to his home in his early 20s. According to family accounts, he reappeared as a penniless itinerant. Despite this, he was successful in wooing and marrying Pareārohi Wiriwiri, daughter of Tutūnui Te Kanawa (also known as Tangi Te Hau) of Ngāti Uekaha. Huiatahi, also known as Te Pioi Pareārohi, was their only child. Thomas had two other wives: Erena, with whom he had a daughter, Okioki, and Te Mamae Whakamau Wilson.
Huiatahi grew up immersed in the language and culture of Ngāti Uekaha and Ngāti Maniapoto. His maternal grandfather, Tutūnui Te Kanawa, had played a prominent role in setting up Pōtatau Te Wherowhero as the first Māori King. His mother was an adherent of the Pai Mārire faith. She was also a tohunga of note, one of the few women permitted to speak on the marae. Huiatahi was to inherit her leadership responsibilities. As a child he was regularly sent back from his home at Waitomo to Taranaki and Waiharakeke to spend time with relatives of his father.
Huiatahi grew up at a time when Ngāti Maniapoto were reaching a tentative accommodation with the Pākehā world. They retained strong links to the King movement, and were wary of a government that had confiscated the lands of their Waikato neighbours. Nevertheless, in 1883 they negotiated a pact to allow the main trunk railway line to pass through the King Country and agreed to milling of their extensive timber stocks. As a young man Huiatahi worked on the family farm, supplementing his income by work as a farm and mill labourer and farrier. He became an accomplished boxer in his youth and an expert in mau taiaha (the traditional martial arts). In later years he was to become known as a boxing trainer and a master tutor in the use of the taiaha for the young men of Ngāti Maniapoto.
As an only child Huiatahi was expected to develop expertise in a wide range of Māori and Pākehā activities. He was an expert genealogist and tribal historian and became a major figure in the Pai Mārire church, upholding their traditions and encouraging daily participation in prayers and Bible study. Huiatahi served on the Pōhatuiri and Ōtorohanga village committees and on the Maniapoto District Māori Council. He was a strong supporter of Māori adult education, tutoring classes in waiata. Huiatahi’s first wife was Raumīria; they had a daughter, Rangimamae.
He later married Huihana Parehuiroro Tana (Turner) of Ngāti Kinohaku and Ngāti Rora; they lived at Pōhatuiri, near Waitomo Caves, where they raised their 12 children, and a child of Huiatahi's from an earlier relationship. As their children reached adulthood and had families of their own, Huiatahi and Huihana were recognised as the kokoro (patriarch) and kuikui (matriarch) of Waitomo.
When aged about 50 Huiatahi was blinded in an accident. Although he was unable to do further paid labour, he and his wife continued with their daily and seasonal routine of planting, tending and harvesting their gardens. He remained the leader of Ngāti Uekaha and a spokesman for Ngāti Maniapoto. He was an active member of the Rātana church, and was ordained as a minister in 1925.
Huiatahi Barrett died at Waitomo on 27 October 1952, survived by his wife, four sons and three daughters. He had embodied all the qualities of a community leader. He was loved by his hapū and highly respected by other community leaders. A fine orator, he was a veritable treasure house of Maniapoto whakapapa and history.