It flows east from its sources in the Mataraua Forest, turning southeastward after about 20 kilometres (12 mi) on joining with the small Awarua River.

It then turns south again, passing Titoki and then joining with the Wairua River to form the Wairoa River approximately halfway between Whangārei and Dargaville.

The New Zealand Ministry for Culture and Heritage gives a translation of "stream of the New Zealand passionfruit vine" for Mangakāhia.

[1] "Place name detail: Mangakahia River".

This article about a river in the Northland Region is a stub.