Sixty-seven thousand years ago, magma punched through three craters here. Lava poured in every direction, much of it flowing toward what is now Onehunga, spreading over 20 square kilometres and making Maungakiekie the second-largest eruption site in the Auckland volcanic field, behind only Rangitoto Island. The scoria cones that remain, one intact and two breached by their own lava flows, look unremarkable beneath the green grass today. But the deep, fertile soil they left behind explains what happened next. The volcanic terraces made this one of the most productive agricultural sites in pre-European Aotearoa.

By the 17th century, the terraces of Maungakiekie had been shaped into a formidable pā by Ngāti Awa chief Tītahi, who carved the slopes into the defensive earthworks known as Ngā Whakairo a Tītahi. At the mountain's summit, the umbilical cord of rangatira Korokino was buried, and a tōtara sprig planted above it. The cone and its surroundings supported an estimated 5,000 people. When Kiwi Tāmaki, the third paramount chief of the Waiohua confederation, moved his seat of power here from nearby Maungawhau, he brought with him a gigantic pahū pounamu, a greenstone gong called Whakarewa-tāhuna, which he struck to summon warriors from across the Tāmaki isthmus. On the southern slopes, Tahuri, an agriculturalist and wife of chief Te Ika-maupoho, managed extensive kūmara plantations. The mountain was not merely a fortress. It was a capital.

The Waiohua era ended in the 1740s after conflict with Te Taoū of Ngāti Whātua. European ownership followed. In 1853, Auckland businessman John Logan Campbell purchased the surrounding land and renamed it the One Tree Hill Estate. He farmed cattle and sheep, planted what became New Zealand's only commercial olive grove until the 1980s, and planned an Italian-style mansion his wife Emma rejected. After the death of his daughter Ida in 1880, Campbell decided to give the estate to the public. He formalized the gift in 1901, during a visit by the Duke and Duchess of Cornwall, who would later become King George V and Queen Mary. Campbell is buried beneath a plain granite slab at the summit, directly below the stone obelisk he funded. The obelisk, designed by Richard Abbott and completed in 1940, was not unveiled until 24 April 1948, delayed by Māori custom that forbids such ceremonies during times of bloodshed.

The obelisk's meaning has always been contested. Campbell intended it as a tribute to Māori, but the term 'memorial' drew objections, and the structure's colonial framing sat uneasily on a mountain sacred to tangata whenua. A 2014 Treaty of Waitangi settlement vested ownership of Maungakiekie and 13 other tūpuna maunga in the Ngā Mana Whenua o Tāmaki Makaurau collective of 13 Auckland iwi and hapū. The Tūpuna Maunga Authority now administers the land, and in 2019 the summit road was permanently closed to vehicles. Meanwhile, the mountain's fame traveled in unexpected directions. U2 wrote 'One Tree Hill' for their 1987 album The Joshua Tree, honouring New Zealand roadie Greg Carroll, who died in a Dublin motorcycle accident in 1986. The song inspired a teen television drama. An asteroid discovered at the Auckland Observatory in the One Tree Hill Domain carries the name 23988 Maungakiekie.

On 11 June 2016, at dawn, the Tūpuna Maunga Authority planted nine young tōtara and pōhutukawa on the summit, grown from parent trees on the maunga itself. The plan is patient: the strongest single tree will eventually remain, and kiekie vines will be added, restoring the plant that gave the mountain its Māori name, Maungakiekie, meaning mountain of the kiekie vine. Combined with neighbouring Cornwall Park, the domain creates 540 acres of unbroken green space in the middle of Auckland, where sheep still graze and both harbours are visible from the summit. The bare hilltop, for now, is not empty. It is becoming something, slowly, on its own terms.