During the Edo period, the area was part of the holdings of Tosa Domain ruled by the Yamauchi clan from their seat at Kōchi Castle, and Sukumo itself was a castle town centered on an outlying fortification of the domain.

Following the Meiji restoration, the village of Sukumo within Hata District, Kōchi with the creation of the modern municipalities system on April 1, 1889.

On March 31, 1954, Tsukumo merged with the neighboring town of Kozukuchi and the villages of Hashigama, Hirata, Yamana, and Okinoshima to form the city of Sukumo.

Sukumo has a mayor-council form of government with a directly elected mayor and a unicameral city council of 14 members.

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