The eastern part faces the Bungo Channel and is within the borders of the Nippō Kaigan Quasi-National Park.

Following the Meiji restoration, the town of Saeki within Minamiamabe District, Ōita was established on May 1, 1889 with the creation of the modern municipalities system.

In July 1916, the name of the town was changed from "Saeki" to "Saiki" to reflect the local dialect, with the kanji of the name remaining the same.

In February 1934, the Saeki Naval Air Corps of the Imperial Japanese Navy was established in Saiki to conduct air patrols to ensure the safety of the Bungo Channel, where warships sailing from Kure Naval District located in the Seto Inland Sea exited to the Pacific Ocean.

Due to its military significance, the city was bombed six times during World War II.

Saiki has a mayor-council form of government with a directly elected mayor and a unicameral city council of 25 members.

In terms of national politics, the city is part of the Ōita 2nd district of the lower house of the Diet of Japan.