Potatau was born in the Waikato, the son of a chief and the descendant of the captains of both the Tainui and Te Arawa canoes. He grew up in a period of relative peace for the Waikato iwi but he became heavily involved in the on going conflict with the Ngati Toa under Te Raparaha. When the Ngati Toa left Kawhia and began their long migration to Taranaki Potatau led a large force of Waikato warriors in pursuit.
Early in 1822 the Waikato forces suffered a heavy defeat and Potatau was almost killed when he refuse to retreat and abandon the body of a slain chieftain. He was saved by the intervention of Te Rauparaha but subsequently had engage a number of enemy chiefs in single combat. Eventually his own people returned and a truce was negotiated. Potatau returned to the Waikato in time to unsuccesfully defend his tribe against the Ngapuhi, armed with muskets and led by Hongi Hika on their great rampage through the North Island. Eventually the Ngapuhi withdrew and the Waikato were able to re-establish themselves on their tribal land. When the Ngapuhi reappeared some ten years later the Waikato were also armed with muskets and were able to defend themselves successfully.
Initally Potatau was very well disposed towards the Pakeha arrivals in his territory, his daughter, Tiria, married a trader. From about 1830 onwars the missionaries had increasing influence in the Waikato. However he refused to sign the Treaty of Waitangi when asked to do so but none the lsee, supported the Colonial overnment. In 1844 he hosted a large inter tribal gathering at Remuera. He built a house on what is now the Auckland Domain and it was the scene of many discussions and negotiations concerning the implementation of the Treaty. He also sold some tribal land around Manukau. However in 1846 he protested vehemently about an edict that land not actually occupied and cultivated by the Maori was to regrded as Crown property. In 1849 he signed an agreement with the governor, George Grey to provide Auckland with military protection should it become necessary.
In the early 1850's a movement to establish a Maori King developed. This had a two fold purpose, to unite the Maori people and to act as a counterbalance to Queen Victoria. The main impetus though was to halt the sale and alienation of Maori land by the Pakeha Government. When he was asked to assume the Kingship Potatau was initally reluctant but he did eventually accept and he was crowned at Ngaruwahia in 1858.
Potatau himself wished to continue to work in cooperation with British Government but many of his followers adopted a much more indepenant position. Gradually the two side polarised a grew apart culminating some five years later in warfare, seeInvasion of the Waikato.
Potatau himself died at Ngaruwahia, 25 June, 1860 and was succeeded by his sone, King Tawhiao