Ngātuere was born at Te Pāparu, a Wairarapa pā near Te Ahikōuka, in the vicinity of the Waiōhine River. His father was Tāwhirimātea and his grandfather Te Ātāhuna, both leaders of Ngāti Kahukura-awhitia, one of the most populous hapū of Ngāti Kahungunu in Wairarapa. His mother was Kaurangaihi. Ngātuere had kinship ties with many hapū, including Ngāti Te Tohinga, Ngāi Tamahau, Ngai Tūāwhio, Ngāi Tūkoko, Ngāti Rongomaipare, Ngāti Tāneroa and Ngāti Waipūhoro. He was said to be 117 years of age at his death; if so, he was born as early as 1772. It is certain that his life spanned the whole period of Pākehā colonisation, and that he had to deal with its effects in Wairarapa when already an elderly man. He showed a marked capacity to change in the face of the new. He was a strong character and asserted his traditional authority against both younger men and Pākehā newcomers.
Ngātuere gave an account to the Native Land Court of the migration of Ngāti Kahukura-awhitia from Heretaunga (Hawke's Bay) to Wairarapa. Three brothers, one of them Pōuri from whom Ngātuere was descended, brought Te Rangitāwhanga, a great-grandson of the ancestor Kahukura-awhitia, to his mother's relatives in Wairarapa. Pōuri negotiated with Te Rerewa, Te Rangitāwhanga's uncle, the right to occupy land in exchange for carved canoes. The land included the district where Ngātuere was born, near present day Greytown. Ngāti Kahukura-awhitia gradually cleared the forest, until in the time of Tāwhirimātea, father of Ngātuere, it had become an open plain.
Little is recorded of the early life of Ngātuere, except the various places where his people lived while he was a youth. By the 1820s, when the northern peoples who had migrated to the Cook Strait coast invaded the Wairarapa region, he was already a major tribal leader. His people were driven from their homes by a war expedition led by Mananui Te Heuheu Tūkino II of Ngāti Tuwharetoa. His wife's father was carried off at the battle of Tauwharenīkau (Tauherenīkau); later, one of Ngātuere's elder brothers was killed at Te Waihinga by Ngāti Toa. Ngātuere was one of the chiefs who escaped after the defeat at Pēhikatea about 1834. After this event most of the people of Wairarapa, including Ngātuere, took refuge at Nukutaurua on the Māhia peninsula. Before the flight north, Ngātuere said, 'they constantly fled from place to place in fear'.
They were away about eight years, and then returned after negotiations with Te Wharepōuri of Te Āti Awa. At first the Wairarapa people stayed together for mutual protection. Then, as their confidence grew, they began to reoccupy their former lands. Ngātuere and his people went back to the area around Te Ahikōuka and Pāpāwai. At this time Pākehā settlement of Wairarapa was just beginning. The region was being explored by surveyors of the New Zealand Company and settlers were looking for land to graze their sheep.
In this situation Ngātuere responded vigorously to challenges to his authority as a person of mana. These challenges came from younger men, more experienced in dealing with Pākehā, such as Te Mānihera Te Rangi-taka-i-waho and Rāniera Te Iho-o-te-rangi; from the agents of the Crown; and from the missionary William Colenso, who seems to have deliberately affronted his mana. In 1846 Ngātuere received Colenso with kindness at his new pā, Ōtaraia, on a bend in the Ruamahanga River, just above Lake Wairarapa, but the missionary's arrogant nature and tone of moral superiority soon led to bitter quarrels.
In 1847 a road was being built from the Hutt Valley north to the place where the town of Featherston would be founded. Colenso feared that his converts in the district, which was part of his 'parish', would suffer evil results from working on the road, that they would work on Sundays, and be exposed to the temptations of alcohol and prostitution.
Ngātuere had quarrelled violently with the Pākehā roadworkers and withdrawn his people from the work. But he took the chance to damage Colenso's reputation by spreading the story that the missionary had warned him that the road would be used by the military to destroy the Māori. William Williams, the East Coast missionary, considered that Ngātuere had tried to discredit Colenso because he had objected to Ngātuere's allowing a young girl to co-habit with one of the roadworkers.
The relationship between Ngātuere and Colenso grew worse. He refused to go near Colenso's tent at Kaikōkirikiri, north of Masterton, unless a tohunga, whom Ngātuere believed to have killed his daughter, Ani Kānara Maitū, by witchcraft, was sent away. He and his brother Ngāiro made Colenso's work difficult by encouraging horse-racing at Kopuaranga and allowing the young men to drink spirits. At the marriage of Hēmi Te Miha, when both men were present, Colenso grossly insulted Ngātuere and Ngāiro by tossing aside their gift of tobacco. Smoking, for Colenso, was another moral evil. The enraged Ngātuere vowed he would never allow a Christian minister to settle in his district.
Ngātuere's frequent rages and acts of violence earned him an unfavourable reputation among settlers who were, however, happy enough to accept his protection when they needed it. W. B. D. Mantell described him as a bully. However, a man of his time and standing would have been under a severe strain in coping with the coming of colonisation. And in fact he did respond positively to those changes, even though an old man. He learned to write fluently in Māori and was capable of dealing shrewdly with Europeans over land matters. He consistently opposed the agents of the Crown who were seeking to buy land, and was able to hold on to his own interests when others were losing theirs. While others failed to protect themselves, he was able to prevent the settler B. P. Perry from occupying a section of the Taratahi block, and to remove C. B. Borlase from his Waihākeke run.
In his later life he was constantly at odds with Te Mānihera Te Rangi-taka-i-waho. These clashes began in 1848 when some junior chiefs forged the signatures of Ngātuere and other senior chiefs on a deed purporting to sell the Tauwharenīkau block to the Crown. Then in 1852 Te Mānihera added insult to injury by allowing his horse to beat those of Ngātuere and Ngāiro at the Kopuaranga races. There were differences, too, over land sales, and over the establishment at Pāpāwai of a missionary centre, college and Māori township. The Pāpāwai flour mill, built by the government, became the source of bad feeling between the two chiefs. Te Mānihera, determined to be the main patron of Pāpāwai, did all he could to prevent Ngātuere and his people from using the mill. By 1868 Ngātuere had withdrawn his people from Pāpāwai altogether.
The Wairarapa rūnanga, established in 1859, was also a source of dispute between Ngātuere and Te Mānihera. Ngātuere's brother, Ngāiro, had been one of its founders, but Te Mānihera was soon seen as its leader. In 1860 a 'fearful row' broke out between Ngātuere and some Ngāi Tahu over the ownership of the Hurunuiōrangi reserve. Te Mānihera and the rūnanga supported the Ngai Tahu claim, while Ngātuere turned to the government for support.
Ngātuere was not wholly opposed to the rūnanga, or to the King movement and the Pai Marire religion. His brother was deeply involved in all three, and the two seem generally to have been in agreement. He promptly accepted the invitation to attend the Kohimarama conference of 1860, and this induced other chiefs to go, including Te Mānihera. In the war that followed Ngātuere kept Wairarapa from becoming another theatre of war. Though there were plenty of land disputes with the government, Ngātuere refused to allow local people, in association with a Hauhau faction, to attack settlers. He took up a pro-government position in order to protect his own and his people's interests.
A Wairarapa tradition tells that Ngātuere went to meet an approaching, hostile war party, either King movement or Hauhau, in the mid 1860s. He met them 10 miles north of Masterton, and so great were their numbers, his mouth dropped open in surprise. The place came to have the name Mikimikitanga-o-te-mata-o-Ngātuere-Tāwhirimātea-Tāwhao (surprise on the face of Ngātuere Tāwhirimātea Tawhao). It was later shortened to Mikimiki, but a road sign bearing the full name, one of the longest in New Zealand, was erected in 1975. A further tradition records that at the spot where Ngātuere and other chiefs met Governor George Grey to discuss the keeping of peace in Wairarapa, a huge tōtara post was erected and named after Ngātuere, 'Poroua Tāwhao'.
Although an Anglican clergyman, the Reverend Pineaha Te Mahauariki, officiated at his burial, Ngātuere may never have become a Christian. At Native Land Court hearings (with only one late exception) he did not swear on the Bible, but gave an affirmation. He had more than one wife: Te Mapu, the sister of Te Mātorohanga, the tohunga and sage, whose knowledge was recorded by Hoani Te Whatahoro Jury; Mere Makarini; and Ani Pātene.
Although he was considered 'loyal', and was at one time appointed an assessor for the Native Land Court, he was too independent and autocratic to be appreciated by Europeans. But to his own people he was the embodiment of mana and tapu. He died on 29 November 1890 and was buried near Waiōhine, not far from his place of birth. He was survived by four daughters and three sons, of whom two are known: a son, Kīngi Ngātuere, and a daughter, Ākenehi Ngātuere. A carved figure representing him stands at Pāpāwai.