Tūpaea of Te Whānau-a-Tauwhao hapū of Ngāi Te Rangi was born probably at Tauranga. He was the son of Te Waru and his wife, Hine Te Oro. He could trace his ancestry to Toroa of the Mātaatua canoe, to Tia and Tapuika of Te Arawa canoe and to Tauroa from Kāwhia. In the 1830s he succeeded his father as the major leader of Ngāi Te Rangi. Tūpaea had two or more wives, one of whom was Te Pākōwhai. He had three sons and two daughters. Until 1852, when he moved to Mōtītī Island, he resided mainly at Ōtūmoetai, one of the principal pā of Tauranga.
As a young man Tūpaea probably fought against the invading musket-armed Ngāpuhi in 1818 and 1820, and against Ngāti Maru in 1828. He was almost certainly with Ngāi Te Rangi who assisted Te Waharoa of Ngāti Hauā against Ngāti Maru at the battle of Taumatawīwī in Waikato in 1830. When Ngāpuhi raids resumed in the early 1830s Ngāi Te Rangi were well prepared with a plentiful supply of firearms. In 1831 Tūpaea and Te Waharoa won a notable victory at Mōtītī Island: they destroyed a war party of 150 Ngāpuhi and Ngāti Kurī warriors led by Te Haramiti.
Ngāi Te Rangi had a serious territorial dispute with Te Arawa, from whom they had seized the Bay of Plenty coast around 1700. When Phillip Tapsell began trading at Maketū in 1830 many Te Arawa moved to the coast to prepare cargoes of flax to trade for guns. Since Ngāi Te Rangi also wanted to trade, Tūpaea, who had sold land at Maketū to Tapsell in return for muskets, gunpowder, lead and tobacco, built a pā nearby, at Te Tūmū. Tapsell found Tūpaea 'the best friend he had, and the most honorable in his dealings'. But competition for the coast and its resources created serious tensions between local tribal groups.
On Christmas Day 1835 Te Hunga, a kinsman of Te Waharoa, was killed, probably by Haerehuka of Te Arawa. Three months later Te Waharoa led his warriors to Maketū to exact utu: on 28 March 1836 they destroyed Te Arawa's pā and Tapsell's trading station. Tūpaea, supporting Te Waharoa, was present and saved Tapsell and his family. Te Arawa then avenged the sack of Maketū by destroying Te Tūmū on 5 May 1836. Before the pā fell Hikareia, Tūpaea's uncle, sent Tūpaea, wounded in the head, with a guard of warriors back to Tauranga, so that Ngāi Te Rangi would not be left leaderless. Hikareia and many other Ngāi Te Rangi were killed. Although Te Arawa regained their position on the coast, warfare continued until peace was made in the mid 1840s. Maketū and Tauranga were frequently raided, their plantations plundered and their inhabitants killed. In 1842 Tauranga also suffered the destruction of Ōngare pā by Tāraia of Ngāti Maru. Towards the end of the wars Tūpaea was described as embittered by the ravages his tribe had sustained and reluctant to make peace with Te Arawa.
Tūpaea did not sign the Treaty of Waitangi when it was presented to him in April and again in May 1840. Crown negotiators believed that he refused because of his association with Catholic missionaries, but this has not been proved. On 30 April 1848 he was baptised by the Anglican missionary A. N. Brown, taking the names Hōri Kīngi (George King), and became a mission teacher for Ōtūmoetai. In April 1851 he led a large party of Ngāi Te Rangi to Thames to make peace with Ngāti Maru. But war nearly resumed in 1852 in a dispute with Te Arawa over Mōtītī Island. With Waikato support Tūpaea built Karioi pā on the island and peace was maintained. Sometime in the late 1850s Tūpaea left Mōtītī; he was living on the lower Wairoa River, at Tauranga, when he became engaged in a brief war with Ngāti Hangarau in 1859–60.
Many Ngāi Te Rangi fought for the King during the war in Waikato and at Tauranga in 1863–64, but Tūpaea adopted a neutral stance and retired to Pātetere. However, after the battle of Gate Pā, on 29 April 1864, he returned to Tauranga and built a pā at Kaimai, at the head of the Wairoa River. Although he was reported to have declared himself a 'rebel', he took no part in the battle of Te Ranga on 21 June 1864. Nevertheless he was soon involved with the Pai Mārire movement. He is alleged to have sent letters to Ngāi Te Rangi on 23 December 1864, calling on them to go inland before 26 December to be saved from destruction, and saying that before the end of January 1865 the angel Gabriel's prophecy to Te Ua Haumēne, the Pai Mārire leader, would be fulfilled and all Europeans would leave New Zealand. Over 1,000 Tauranga Māori left for the mountains. When the prophecy proved false most returned, but not Tūpaea. With an unarmed party he attempted to join other followers of Pai Mārire on the East Coast and was captured near Rotoiti by Ngāti Pikiao of Te Arawa. He was kept prisoner for some time in Auckland, but was released after making a declaration of loyalty to the Queen. He denied sending the letters.
When assessors were appointed for Tauranga in 1862 Tūpaea was passed over, although he was a major chief. He was later made an assessor to the Native Land Court and received a pension, £20 in 1871–72, and £50 a year thereafter. In 1867 he and other Ngāi Te Rangi chiefs signed the sale of the Katikati and Te Puna blocks, a land sale that was resisted by the Pirirākau people. Dissident Ngāti Porou attempted to support Pirirākau, but Tūpaea's opposition caused them to return to Mataora in November 1867. In 1870, when Te Kooti threatened Tauranga, Tūpaea assured the European population that he would fight if the settlement was attacked.
In 1878 Tūpaea visited Wellington to consult with the government over tribal problems at Mercury Bay; he was a guest of Sir George Grey, then premier. In his later years he lived at Rangiwaea Island, near Tauranga, where he died on 26 January 1881. His tangi was held there and he was buried on Matakana Island.
Reserved in speech and dignified in manner, Hōri Tūpaea was respected for his integrity. He ably led his people through years of intertribal struggles and protected their interests as European settlement was established.