Geographically, it lies on the northern coast of Hainan Island, bordering Wenchang to the east, Chengmai to the west, Ding’an to the south, and facing the Qiongzhou Strait to the north. It covers a land area of 2,297.04 square kilometers plus a sea area of 785.06 square kilometers, with four county-level districts under its jurisdiction: Xiuying, Longhua, Qiongshan and Meilan. As of late 2023, its permanent population reached about 3 million.

Haikou features a tropical monsoon climate with warm winters and cool summers, abundant sunshine and clean air that consistently ranks among the top nationwide. It enjoys spring-like weather all year round, earning a reputation as a livable eco-coastal city.