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

Per the Shoku Nihongi, following a huge earthquake in the year 715 AD, a large number of people migrated to this area from the southern Kantō region, forming numerous fortified settlements.

Following the Meiji restoration, the town of Nakaniida was established within Kami District, Miyagi with the creation of the modern municipalities system.

Kami has a mayor-council form of government with a directly elected mayor and a unicameral town council of 18 members.

In terms of national politics, the town is part of Miyagi 4th district of the lower house of the Diet of Japan.