The I-Kiribati people settled what would become known as the Gilbert Islands between 1000 and 1300 AD. Subsequent invasions by Fijians and Tongans introduced Micronesian and Polynesian elements to the Micronesian culture, but extensive intermarriage has produced a population reasonably homogeneous in appearance and traditions.

European contact began in the 16th century. Whalers, slave traders, and merchant vessels arrived in great numbers in the 1800s, fomenting local tribal conflicts and introducing often fatal European diseases. In an effort to restore a measure of order, the Gilbert and Ellice Islands (the Ellice Islands are now known as Tuvalu) consented to becoming British protectorates in 1892. Banaba (Ocean Island) was annexed in 1900 after the discovery of phosphate-rich guano deposits, and the entire collection was made a British colony in 1916. The Line and Phoenix Islands were incorporated piecemeal over the next 20 years.

Japan seized the islands during World War II. In November 1943, U.S. forces assaulted heavily fortified Japanese positions on Tarawa Atoll in the Gilberts, resulting in some of the bloodiest fighting of the Pacific campaign. The battle was a turning point in the Central Pacific.

Britain began expanding self-government in the islands during the 1960s. In 1975 the Ellice Islands separated from the colony and in 1978 became the independent country of Tuvalu. The Gilberts obtained internal self-government in 1977, and formally became an independent nation on July 12, 1979, under the name of Kiribati.

Post-independence politics were initially dominated by Ieremia Tabai, Kiribati's first president, who served from 1979 to 1991, stepping down due to Kiribati's three-term limit for presidents. Teburoro Tito's tenure as president, 1994-2003, also was curtailed by the three-term limit, though in his case his third term lasted only a matter of months before he lost a no confidence motion in Parliament. (Note: See the next section for an explanation of Kiribati's unique presidential system.) In July 20003, Anote Tong defeated his elder brother, Harry Tong, who was backed by former-President Tito and his allies. An ensuing court challenge which alleged violations of campaign finance laws could have unseated President Tong. However, in October 2003, a judge specially brought in from Australia to ensure strict neutrality, ruled in President Tong's favor.