Kailua-Kona is an unincorporated community and census-designated place in Hawaii County, Hawaii, United States. Located along the shoreline of Kailua Bay and up the southern slope of Hualālai volcano, it serves as the center of commerce and the tourist industry on the island's west side. It is the second-largest settlement on the island of Hawaii after Hilo and the largest on its western coast.

The community was established by King Kamehameha I as his seat of government before he consolidated rule of the archipelago in 1795. It later functioned as the capital of the newly unified Kingdom of Hawaiʻi before the capital moved to Lāhainā and then Honolulu. Royal fishponds at Kaloko-Honokōhau National Historical Park served as a hub for unified Hawaiian culture, and the town remained a retreat for the royal family until the late 1800s.

Aliʻi Drive forms the oceanfront downtown street, designated as the Hawaii Scenic Byway known as the Royal Footsteps Along the Kona Coast. Notable sites include Kamakahonu royal residence, Ahuʻena Heiau, King Kamehameha's Kona Beach Hotel, and Huliheʻe Palace. The area features historic churches like Mokuaikaua Church and parks such as La'aloa Bay and Kahaluʻu Bay, which is a popular snorkeling location.

The region hosts the annual Ironman World Championship triathlon, the Kona Coffee Festival, and the Hawaiian International Billfish Tournament. Kona coffee is cultivated on the slopes of Hualālai and Mauna Loa, with historical sites managed by the Kona Historical Society. Boat tours departing from the pier allow visitors to watch dolphins, whales, manta rays, and turtles in the ocean.

The population was 19,713 at the 2020 census. The economy has seen significant growth fueled by tourism and investment, with visitor air arrivals increasing substantially in the early 2010s. Kailua-Kona is served by Kona International Airport and experiences a tropical, semi-arid climate with warm temperatures year-round, making it the warmest place in the United States in January on average.