Kapolei is a planned community in the City and County of Honolulu, Hawaiʻi, United States, on the island of Oʻahu. In 1977, the government designated it as the "second city" of Oʻahu, in relation to Honolulu. For statistical purposes, the United States Census Bureau has defined Kapolei as a census-designated place (CDP) within the consolidated city-county of Honolulu. As of the 2020 census, Kapolei had a population of 21,411.