Maronui signed the East Coast sheet of the Treaty of Waitangi between 5 and 12 May 1840 at Tūranga (now Gisborne). He was from the Ngāti Kaipoho hapū (subtribe) of the Rongowhakaata iwi (tribe).
Maronui composed an oriori (lullaby) for his grandchild, Rua-tapu-nui.