The town of Pauanui is on the east coast of the Coromandel Peninsula in the North Island of New Zealand. It lies at the mouth of the Tairua River on its south bank, directly opposite the larger town of Tairua.

The Coromandel Peninsula on the North Island of New Zealand extends 85 kilometres (53 mi) north from the western end of the Bay of Plenty, forming a natural barrier protecting the Hauraki Gulf and the Firth of Thames in the west from the Pacific Ocean to the east. It is 40 kilometres (25 mi) wide at its broadest point. Almost its entire population lives on the narrow coastal strips fronting the Hauraki Gulf and the Bay of Plenty. In clear weather the peninsula is clearly visible from Auckland, the country's biggest city, which lies on the far shore of the Hauraki Gulf, 55 kilometres (34 mi) to the west. The peninsula is part of the Thames-Coromandel District and the Waikato Region.