It is located in the center of Kumamoto Prefecture, the city limits extend from the northern coast of the Yatsushiro Sea to the east inland, the south and west sides of the Uto Peninsula, and Tochijima Island, located south of the western tip of the peninsula.

After the Meiji restoration, the town of Matsubase was established with the creation of the modern municipalities system on April 1, 1889.

The city of Uki was established on January 15, 2005, as a result of the merger between the towns of Misumi and Shiranuhi (both from Uto District), and the towns of Matsubase, Ogawa and Toyono (all from Shimomashiki District).

Uki has a mayor-council form of government with a directly elected mayor and a unicameral city council of 22 members.

Uki, collectively with the town of Misato, contributes two members to the Kumamoto Prefectural Assembly.

In terms of national politics, the city is part of the Kumamoto 4th district of the lower house of the Diet of Japan.