4 December is often-quoted as his birthday and is a public holiday in Tonga; however, it was the date of his coronation in 1845 as Tuʻi Kanokupolu, when he took the name Tupou.

His father was Tupouto'aʻ, who aspired to be the 17th Tuʻi Kanokupolu, but he was not recognized as such by the high chiefs of Tongatapu, as he was viewed as a low ranking usurper from Haʻapai.

His mother, Hoamofaleono, felt her life was at risk on Tongatapu, so she fled with her son to Haʻapai, probably within the year of his birth.

The pregnant Hoamo fale ono felt insecure in Tongatapu as she was about to give birth to a child whose father, Tupouto'a, was the primary adversary of her clan (Ha'a Havea Lahi).

Tuku'aho was cruel and feared by all, including Ha'a Havea Lahi chiefs, given such acts as the burning of Fangale'ounga, a Vaini colony of Ma'afutuku'i'aulahi.

The retribution by Tuku'aho on Ha'a Havea was regarded, despite the fact Niukapu was not part of the clan, as a demotion in power and a display of disrespect of territorial boundaries.

He inherited the conflicts with the overlords of Tongatapu, in particular with Laufilitonga, the last Tuʻi Tonga, who tried to extend his role as spiritual leader into a more political one and contested Tāufaʻāhau in Haʻapai.

However, It was Kauvakauta of 'Eua whom conquered The Mighty Kolo Tau o Velata in Ha'apai and assisted Tāufaʻāhau with guns and ammunition for his wars throughout Tonga.

In 1852, the last independent chief, Takai Mo Fa'e, fell and Tāufa became the undisputed leader of the whole of Tonga.

This led to the constitution stating that land in Tonga could only be given to natural-born Tongans and not sold to outsiders, as is still the case today.