Honolulu County, officially the City and County of Honolulu, is a consolidated city-county in the U.S. state of Hawaii. It encompasses Urban Honolulu, the state capital, along with the remainder of Oʻahu island and several minor outlying islands, including all Northwestern Hawaiian Islands except Midway Atoll. This jurisdiction manages government aspects traditionally divided between municipalities and counties elsewhere in the United States, serving as a central administrative hub for the archipelago.

The consolidated entity was established through a city charter adopted in 1907 and accepted by the Legislature of the Territory of Hawaii. Previously known as Oʻahu County, it evolved from a humble village named Honolulu, meaning sheltered bay, which gained prominence when King Kamehameha I moved his royal court there in 1809. The area later became the kingdom's capital in 1845 and saw significant development following annexation by the United States and subsequent statehood.

The county is defined by its diverse districts, ranging from Waikīkī and Diamond Head to Kalihi and Pearl Harbor. Its civic center, coextensive with the Capitol District, houses Honolulu Hale, established in the 1920s as a city hall structure. The jurisdiction includes major national protected areas such as the James Campbell National Wildlife Refuge, Papahānaumokuākea Marine National Monument, and the USS Arizona Memorial, reflecting its deep historical and ecological significance.

Honolulu serves as the center of government and commerce for Hawaii, offering a dynamic mix of cultures from across the Pacific Ocean. Visitors are drawn to its historic sites, including former palaces of Hawaiian royalty, and its status as the home of Waikiki Beach, the state's best-known tourist destination. The city provides access to some of Hawaii's best museums and striking natural scenery, balancing its fast-paced urban environment with the laid-back atmosphere characteristic of the islands.

As of 2020, the population was 1,016,508, with about 70% of the state's residents living within the county. It is the widest county in the United States by area, spanning over 1,380 miles from end to end. The economy is supported by major employers and headquarters for companies like Hawaiian Airlines and Bank of Hawaii. Honolulu features a moderate warm to hot climate with little temperature variation throughout the year.