[2] Per Japanese census data,[3] the population of Ōwani has decreased steadily over the past 60 years.

After the Meiji Restoration, it became a village within Minamitsugaru District of Aomori Prefecture with the establishment of the modern municipalities system on April 1, 1889.

On July 1, 1954, it annexed neighboring Kuradate Town, but lost a portion of its territory to Hirosaki City on September 30, 1964.

Ōwani has a mayor-council form of government with a directly elected mayor and a unicameral town legislature of 12 members.

In terms of national politics, the town is part of Aomori 3rd district of the lower house of the Diet of Japan.