Maunawili is a residential census-designated place (CDP) in the City & County of Honolulu, Koʻolaupoko District, Island of Oʻahu, Hawaii, United States. As of the 2010 Census, the CDP had a population of 2,040. Situated mauka (inland or mountain side) of Kalanianaʻole Highway between Castle Junction and Castle Hospital, Maunawili is nearly all private homes, schools, and a few churches; horse stables complete the rural setting. There are no commercial establishments.