Waiuku, town, northern North Island, New Zealand. It lies along the Waiuku estuary, which is the southern arm of Manukau Harbour.
The settlement was founded in 1843 as a port on the route between Auckland and the agricultural area of the Waikato River to the south. Its function as a trading centre ceased with the Waikato War of 1863–64, when it was made a stockade. Waiuku was made a town in 1914.
It lies near the terminus of a line branching from the North Island Main Trunk Railway at Paerata (east) and is the distribution and service centre for a dairy- and mixed-farming region 40 miles (65 km) southwest of Auckland. Its industries include stockyards, light engineering works, small boatbuilding, and the production of butter, knitwear, clothing, and joinery goods. New Zealand’s first steel mill (1970), located at Glenbrook (5 miles [8 km] northeast), uses iron sands from North Head of the Waikato River. Pop. (2006) 7,725; (2012 est.) 8,980.