The area name of Yatomi appears in Kamakura period documents, as part of ancient Owari Province.

During the Meiji period, the area was organized into villages under Kasai District, Aichi Prefecture, with the establishment of the modern municipalities system.

Efforts to merge Yatomi with the neighboring town of Kanie failed in 2004 over a dispute on the naming of the new entity.

Yatomi has a mayor-council form of government with a directly elected mayor and a unicameral city legislature of 16 members.

In terms of national politics, the city is part of Aichi District 9 of the lower house of the Diet of Japan.