Taiaroa, the son of Kōrako and Wharerauaruhe, belonged to Ngāi Te Ruahikihiki and Ngāti Moki hapū of Ngāi Tahu, both of them centred on Taumutu, at the southern end of Waihora (Lake Ellesmere). His ancestor, Te Ruahikihiki, had taken part in the settlement of Banks Peninsula about 1700. Taiaroa was born, probably at his mother's village, Waikākahi, at the northern end of Waihora, in the late 1790s. He was described as being between 27 and 30 years old in 1826. From the 1830s to the 1860s, in association with his cousin Karetai, he held a leadership position at Ōtākou, on the Otago Peninsula, with which his descendants have become closely identified.
The first European record of Taiaroa is his meeting with Captain John Kent of the Mermaid, at Ruapuke Island, in 1823; Taiaroa had been muttonbirding on the east coast of Rakiura (Stewart Island). Kent was told by a rival chief, Te Wera, that Taiaroa had been involved in an attack on members of the crew of the Sophia in 1817. The Sophia's crew, under their captain, James Kelly, had used their sealing knives to drive the hostile party of Māori from the boat and had then burnt the village of Ōtākou in retaliation. The incident probably occurred because crewmembers had stolen tattooed heads on an earlier expedition. By contrast the meeting between Taiaroa and Kent was peaceful. Taiaroa encouraged traders to call at Ōtākou; he and Karetai began manufacturing dressed flax for Kent to ship to New South Wales, and trade increased rapidly, as did the Ōtākou population.
In the mid 1820s Taiaroa became involved in the internecine warfare of Ngāi Tahu of the Canterbury Plains. His sister, Te Parure, was of Taumutu, which was threatened by the major Ngāi Tahu leader Tama-i-hara-nui. Taiaroa led a war party from Ōtākou, won a victory at Wairewa (Lake Forsyth) and sacked a pā on Rīpapa Island, in Lyttelton Harbour. In these affrays Taiaroa warned relatives on the opposing side in time for them to escape attacks by his war party. On several occasions he ran ahead, shouting: 'Escape! Fly for your lives! …We have guns'. Ngāi Tahu from the south had obtained guns from Kent and other Sydney traders earlier than their northern relations. However, the wars between Ngāi Tahu did not spread south and came to an end after 1828, as Te Rauparaha of Ngāti Toa began his invasions of the South Island. Beginning in 1829, after Te Rauparaha's first attack at Kaikōura, southern Ngāi Tahu chiefs sold land to obtain more guns and ammunition. In the 1830s their whaling boats were armed with small cannon when carrying war parties.
Taiaroa was at Kaiapoi pā when it was besieged by Ngāti Toa in 1831. He was returning to Ōtākou, escorted by warriors from Kaiapoi, after a visit there, when the news of the attack by Ngāti Toa on the pā reached him. He returned to Kaiapoi and attempted to set fire to Te Rauparaha's canoes, but was prevented by rain. He entered the pā and joined the besieged Ngāi Tahu. Several months later he left Kaiapoi before it was stormed by Ngāti Toa: he had not been involved in the killing of the Ngāti Toa chief Te Pehi Kupe – the main cause for the attack.
After the capture of Kaiapoi and of Ōnawe pā at Akaroa, Te Rauparaha threatened to conquer the entire South Island. Taiaroa was one of the leading Ngāi Tahu warriors who prevented this. He co-operated with Tūhawaiki in expeditions against Ngāti Toa and may have been with the war party that surprised Te Rauparaha snaring ducks at Kapara Te Hau (Lake Grassmere). It is said that Te Rauparaha was captured, but that Taiaroa allowed him to escape, just as Ngāti Toa had allowed Taiaroa to escape from the siege of Kaiapoi. On this occasion Te Rauparaha swam to a waiting canoe and, after further fighting, escaped to Te Awaiti in Cloudy Bay.
By the mid 1830s the coasts of the Canterbury and Kaikōura areas were almost depopulated by war. Ngāi Tahu war parties from the Ōtākou area and the far south now carried war further north and fought with Ngāti Toa in the Marlborough area, without either tribe's gaining a decisive victory. In 1834 Taiaroa attacked Rangitāne in Queen Charlotte Sound; they had supported Ngāti Toa and Te Rauparaha at the siege of Kaiapoi, and had joined the final assault. Unable to find Te Rauparaha on this occasion, Taiaroa harassed the whaling stations in Cloudy Bay. The fighting effectively removed Ngāti Toa from Ngāi Tahu territory.
In late 1836 or early 1837, at Tūtūrau, Taiaroa was part of the Ngāi Tahu war party that destroyed the war party led by Te Pūoho-o-te-rangi, of Ngāti Tama. Te Pūoho, an ally of Te Rauparaha, had travelled down the West Coast and crossed through Tīoripātea (Haast Pass), before capturing the village of Tūtūrau. Ngāi Tahu fugitives reached Ruapuke Island and a well-armed Ngāi Tahu war party, led by Tūhawaiki and his nephew, Tōpi Pātuki, marched inland and captured the war party, killing Te Pūoho. This Ngāi Tahu victory brought an end to the invasions of the South Island by tribal armies from the north.
In the 1830s Taiaroa did not always enjoy good relations with the whaling communities on the Otago coast. At times he harassed the whalers of Waikouaiti, who were protected by Tūhawaiki; it is said that on several occasions he was driven off by gunfire. In 1834, in partnership with Te Whakataupuka, he sacked the Weller brothers' station in Otago Harbour and plundered the whalers' houses. On another occasion Taiaroa's attempt to capture the American brig, Pearl, resulted in his being clapped in irons until the vessel cleared Otago Heads.
In 1838 Taiaroa travelled to Sydney, where he sold land, including Banks Peninsula, to John Jones and to George and Edward Weller. His land sales often overlapped with or disregarded earlier transactions, which gave rise to conflicting land claims after 1840. He may have bought military supplies in Sydney, because the following year he was one of those who led a large war party to Cook Strait in an attempt to provoke Te Rauparaha into open warfare. This was unsuccessful but Te Āti Awa in Queen Charlotte Sound, fearing attack by Taiaroa, fortified their village in East Bay.
Taiaroa played a major part in the peace negotiations between Ngāti Toa and Ngāi Tahu after the Wairau conflict of 1843. In a situation of growing tension between settlers and Ngāti Toa, Taiaroa appears to have considered an alliance with Te Rauparaha against the Pākehā. He visited Te Rauparaha at Taupō pā, Porirua, and marriages were made to confirm the peacemaking between the two tribes.
Although the name of Taiaroa appears on the copy of the Treaty of Waitangi taken to the Otago region in June 1840, he did not sign. He played a leading role in South Island land sales to the Crown, and in February 1840 was one of a party of Ngāi Tahu leaders with whom Governor George Gipps tried unsuccessfully to negotiate a treaty. Although he professed friendship with the Pākehā he was generally cautious of settlement. However, the depopulation of the South Island's relatively small communities by disease, and the lessening of Ngāi Tahu control over their resources, was weakening the position of the tribe. In June 1844 Frederick Tuckett, a surveyor for the New Zealand Company, persuaded Taiaroa and other chiefs to sell the Otago block for £2,400. Taiaroa and several other Ngāi Tahu leaders later travelled to Wellington to protest that they had not received a 10th part of the Otago block, which had been promised as part of the sale agreement. In 1848 Taiaroa ceded his land rights in Canterbury and in 1853 he was a signatory to the Murihiku sale.
Taiaroa had several wives. The first, Hineiwhāriua, was the sister of Karetai. In 1840 he was with Tarotaro, who had adopted two of his children, probably from his first marriage; according to the French explorer Dumont d'Urville, Tarotaro had tuberculosis. A third wife was named Māwera. Taiaroa's children included Nīkuru, who married Edward Weller, and Hōri Kerei Taiaroa.
The early death of many Ngāi Tahu leaders, especially Tahatū and Tūhawaiki, had brought Taiaroa into a position of greater influence within his tribal group by the 1850s. In November 1856 he attended the intertribal meeting at Pūkawa, Lake Taupō, which elected Pōtatau Te Wherowhero as the first Māori King. In 1860 he travelled to Auckland to attend the Kohimarama conference of Māori leaders, called by the government after war had begun in Taranaki; he later attempted to mediate in the conflict.
On 3 April 1859 Taiaroa had been baptised by a Methodist minister, the Reverend George Stannard, taking the name Te Mātenga (Marsden). On the same day he had married Kararaina, the daughter of Ngātata-i-te-rangi, of Te Āti Awa. In his last years Taiaroa set aside 10 acres of land at Ōtākou and built a church there, although he lived mainly at Pigeon Bay, on Banks Peninsula. He spoke some French and English, as well as Māori. A strongly built man of middle height, he had an aggressive disposition; a weakness for alcohol gravely affected his health. He died on 2 February 1863, at Ōtākou, and was buried on 17 February at Ōtākou marae. Before his death he counselled his descendants to live in peace with the Pākehā and to observe their undertakings.