Mililani is a city located near the center of the island of Oʻahu in Honolulu County, Hawaiʻi, United States. It consists of two census-designated places, Mililani Town, with a population of 27,629 at the 2010 census, and Mililani Mauka, with a 2010 census population of 21,039.
Mililani sits on former plantation fields owned by Castle & Cooke, which began planning for its development in the early 1960s under its Oceanic Properties subsidiary. Castle & Cooke's plan was to make Mililani Town a satellite city by using a prestigious group of planners and architects to satisfy Oʻahu's great pent-up demand for housing with a sensitively designed, affordable new community of a type unique in Hawaiʻi. Architect and developer Al Boeke, who would later create the planned community of Sea Ranch, California, was the development director of Mililani. The first homes in Mililani went on sale on June 3, 1968.
In 1976, the Interstate H-2 opened, cutting travel time from Mililani to Honolulu in half. In 1986, Mililani was named an All-America City in recognition of a community effort to clean up drinking water contaminated with agricultural pesticides. It is the only community in Hawaiʻi ever to receive this distinction. Mililani is the third wealthiest zip code (96789) in the state of Hawaiʻi, according to the 2006 ranking by Pacific Business News.