The Takashima area in of the city is within the borders of the Seto Inland Sea National Park.

According to the Bungo no Kuni Fudoki, the name Ōita was given by Emperor Keiko when he visited this area in the late Kofun period; however, the main urban center was the port of Funai (府内) on the coast.

During the Kamakura period, the Ōtomo clan was appointed shugo of the province, and made Funai their jōkamachi.

By the Sengoku period, the Ōtomo has conquered most of Kyushu and had embraced Nanban culture, with Funai becoming a stronghold of the Kirishitan religion and western technology.

The town of Ōita was established on 1 May 1889 with the creation of the modern municipalities system, and was raised to city status in 1911.

Ōita has a mayor-council form of government with a directly elected mayor and a unicameral city council of 44 members.