Te Whetū signed the Cook Strait (Henry Williams) sheet of the Treaty of Waitangi on 26 May 1840 in Manawatū. He was from the Ngāti Te Ihi Ihi hapū (subtribe) of Ngāti Raukawa. He was married to Aniwaniwa, the daughter of Te Whiti-o-Rongomai. They had at least three children: Karepa Te Whetū, Kare Patengi and Pourangi.
Part of the migrations south from Taranaki, Te Whetū occupied land around the lower Manawatū region. Here he married a Rangitāne woman, Hine-titi, and went with her to the settlement of Te Iwi Te Kari, near Foxton. He was also associated with Himitangi. In 1867 he was recorded by Walter Buller as living in the Rangitīkei-Manawatū Block.
Te Whetū signed for the sale of the Te Kōpua Block in the Ngāti Maru District. Robert Parris, the Civil Commissioner in New Plymouth, paid £230 to the signatories. The following year, Te Whetū and his son Karepa signed for the sale of the Waitara-Taramouku Block No. 1, also in the Ngāti Maru District. Ngāti Maru reserved 330 acres plus two half-acre sections for urupā (burial grounds). The payment was £1,600.