Together with the neighboring city of Shōbara, it forms the northern part of the prefecture called the "Bihoku region".

The center of urban area is the Miyoshi Basin, which is located between the Chugoku Mountains and the Kibi Plateau at an elevation of 150 to 250 meters.

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

Miyoshi has a mayor-council form of government with a directly elected mayor and a unicameral city council of 24 members.

In terms of national politics, the city is part of the Hiroshima 5th district of the lower house of the Diet of Japan.

Light manufacturing is centered on automobile engines and components for Mazda, which also has its test and proving grounds located in the city.