Waiuku is a rural town in the Auckland Region of New Zealand. It is located at the southern end of the Waiuku River, which is an estuarial arm of the Manukau Harbour, and lies on the isthmus of the Āwhitu Peninsula, which extends to the northeast. It is 40 kilometres southwest of Auckland city centre, and 12 kilometres north of the mouth of the Waikato River.

Settled in the 13th or 14th centuries, the Waiuku area was an important transportation hub, as the Te Pai o Kaiwaka portage was the preferred route for people travelling between the Waikato River and Manukau Harbour. The area became a centre for Ngāti Kahukōkā, a Waiohua hapū, by the 15th century. Ngāti Te Ata developed as a union between Waiohua and Waikato Tainui peoples, around the 17th century at Waiuku.

Waiuku became a trading port in 1851, facilitating trade between the Waikato River and the port of Onehunga, and Purapura, a Ngāti Te Ata village was established at the navigable head of the Awaroa Creek to the south. After the Invasion of the Waikato in 1863, the port of Waiuku suffered due to the lack of Māori produce being transported. By the end of the 19th century, Waiuku had begun developing into a centre for the dairy industry. In 1922, a railway line branch was constructed to Waiuku, and by 1955 Waiuku had grown enough to become an independent borough. In 1968, the Glenbrook steel mill opened in neighbouring Glenbrook, becoming a major employer in Waiuku.

The name Waiuku is a Māori name meaning "Waters of Uku"; uku being a type of clay used as a soap. The name recalls the story of a Ngāti Kahukōkā woman of high rank who was choosing between two suitors, Tamakau and Tamakae. Tamakae, having been working in the kūmara gardens, was taken to the river by the elders of the area to be washed using uku from the shores of the Waiuku River, before meeting his potential new wife. The location where Tamakae was washed was the western banks of the Waiuku River, directly behind where the Waiuku Museum stands today.

Waiuku is located at the southern end of the Waiuku River, an estuarial arm of the Manukau Harbour. It is close to the town of Pukekohe to the east, and is directly north of the Waikato River mouth. Prior to European settlement, the Waiuku area was primarily a dense kahikatea-dominated forest, with swamps areas near waterways. Since then, the majority of swamps have been drained.

The Manukau Harbour has been settled by Tāmaki Māori since around the 13th or 14th centuries. Tāmaki Māori of the southern Manukau Harbour traditionally used the food resources of the harbour, collecting shellfish such as cockles, sea urchins and kōura, and fished species including snapper, kahawai and parore.

The Waiuku area was an important due to Te Pai o Kaiwaka, a portage which was the main route for transport between the Waikato River and the Manukau Harbour. The route followed the Awaroa Stream to the northernmost navigable point, after which waka were hauled overland to the Waiuku River. The portage was the preferred route, due to the unpredictable seas of the west coast. The existence of the portage meant that the Waiuku area has historically been difficult to settle during times of war.

The Waiohua hapū Ngāti Kahukōkā began occupying the southern Manukau Harbour and Waikato River mouth around the 15th century. Ngāti Kahukōkā's main centres were Puketapu on the Āwhitu Peninsula, Tītī, near modern-day Mauku.