Ōsaki is a member of the World Health Organization’s Alliance for Healthy Cities (AFHC).

The Kashimadai and Matsuyama districts in the southeastern part of the city are within the commuting zone of Sendai.

The area of present-day Ōsaki was part of ancient Mutsu Province, and has been settled since at least the Jōmon period by the Emishi people.

Ōsaki has a mayor-council form of government with a directly elected mayor and a unicameral city legislature of 30 members.

In terms of national politics, the city is part of Miyagi 6th district of the lower house of the Diet of Japan.