Hēmi Huata was the fourth child of Tāmihana Huata, the first vicar of Wairoa Māori pastorate, who had succeeded the missionary James Hamlin in 1864. Tāmihana was an important chief whose influence on events in the Wairoa area was significant, and Hēmi inherited his father's mana. His mother was Rīpeka, a woman of high rank from Rangiāhua, and he had two elder brothers, Ānaru Huata and Kunaita Pōmare, both of whom died without living issue. He was born in 1866 or 1867 at Rāmoto, Frasertown, north of Wairoa, of Ngāti Kahungunu descent. His main hapū was Ngāti Mihi on his father's side. His mother's hapū were Ngāi Tama-te-rangi and Te Aitanga-a-Hinemanuhiri. Other hapū Hēmi claimed were Ngāti Hinetū, Ngāti Kōtore of Pāpuni, Ngāti Paikea of Mōhaka, Ngāti Hikapi of Waikare (between Mōhaka and Tutira), Ngāti Hika of Te Reinga and Ngāti Ruapani of Waikaremoana.
At a young age Hēmi was taken to Heretaunga, the plains of central Hawke's Bay, to live with a relation while Te Kooti was active in the Wairoa district. When he was living there an aunt was caught pilfering peaches, and he became known as Hēmi Pītiti (Peach) Huata. In 1886 Hēmi attended Te Aute College, at a time when John Thornton was headmaster and Apirana Ngata a fellow pupil. Hēmi, who was also known as James Stuart, was a college prefect in 1890 and captained the 1891 college rugby team that won the Hawke's Bay championship and toured the South Island.
After leaving Te Aute Hēmi went to Te Rau Theological College, Gisborne, and was ordained as a deacon in 1898. He became curate of Mōhaka pastorate, and then vicar after being ordained priest in 1901. He travelled throughout his pastorate on his horse, preaching the gospel, christening new members, marrying couples and administering communion. He also visited the sick, offered many blessings and buried relations throughout the region.
Not long after he was ordained Hēmi married Rōpine Aranui of Ngāti Pahauwera, of Mōhaka. Their marriage was viewed as the beginning of the healing process between Ngāti Pāhauwera and the supporters of Te Kooti. Because of a pact between Tāmihana Huata and Te Kooti, many of Tāmihana's Ngāti Kōtore relations had taken part in the massacre when Te Kooti attacked Mōhaka in 1869. Ropine's ancestor Matenga Te Aohia and other relations had been killed.
Due to Hēmi's inheritance of his father's and mother's mana he became influential in the Wairoa district. He was curate of Wairoa from 1913 to 1919, and after his retirement from the Mōhaka pastorate in 1934 he continued to officiate in his district. He was a very humble and peaceful man and was much loved by his people. He was an acknowledged keeper of Ngāti Kahungunu whakapapa, and contributed to J. H. Mitchell's book Tākitimu, and Apirana Ngata's Ngā moteatea. Hēmi also taught the tradition and whakapapa of Ngāti Kahungunu to his son Te Ōkanga (Aussie), wrote down whakapapa, and kept diaries.
In the early 1920s there was much debate within the Anglican church about the movement founded by T. W. Rātana. Initially membership of the movement was considered to be complementary to church membership. Hēmi Huata was Rātana leader at Wairoa, and supported Taranaki Te Uamairangi as an independent Rātana candidate against Apirana Ngata and others in the Eastern Māori electorate at the 1922 general election. When Rātana came to Mōhaka in the early 1920s Hēmi accompanied him to Wairoa and attended Christmas hui at Rātana pā. But in 1925 the Anglican church pronounced the Rātana movement schismatic and incompatible with Anglicanism. Hēmi found that he could not support two faiths, and left the Rātana movement. However he did not discourage his relations from remaining followers of Rātana.
From 1923 to 1927 Hēmi Huata and Rōpine had a shop at Mōhaka. The business was not very successful because they allowed many of their relatives to run up large accounts. Also some of Hēmi's children would puncture cans of preserves, drink the juice and put them back on the shelves, the damage undetected until customers came to purchase the items.
Hēmi and Rōpine had 11 children. When their first grandchild was born, following traditional custom they took the child to raise as their own. Thereafter Hēmi and Rōpine raised many grandchildren and relations. Their son Wī Te Tau Huata often spoke of having 42 brothers and sisters. Hēmi sent three daughters to Hukarere Native Girls' School, three sons to Te Aute College and two sons to other schools.
In the 1930s Hēmi supported Apirana Ngata's Horohoro Native Land Development Scheme, through which some Ngāti Kahungunu families were relocated to the Rotorua district to help Te Arawa to develop farms. He began to be acknowledged as one of the major speakers on marae throughout the Wairoa area. He had his own marae, Te Huinga-o-te-rangi-ora, at Rāmoto. However, he supported the building of Tākitimu meeting house at Waihīrere (Tākitimu) marae, near Wairoa, and was one of the original trustees. In 1937 Hēmi Huata was a recipient of King George VI's Coronation Medal. During the Second World War he encouraged his sons to enlist. Wī Huata was chaplain to the 28th New Zealand (Māori) Battalion in Italy, and was awarded the Military Cross for his service.
On 13 October 1954 Hēmi Huata died at Rāmoto. He was buried on 17 October at Te Poho-o-Rakaihākeke cemetery, Rāmoto, at his father's feet. Rōpine was buried there when she died in 1959.