Marengo is a village in Morrow County, Ohio, United States. The population was 297 at the 2000 census. Marengo is south of Mount Gilead, the county seat.
Marengo is located at 40°24′5″N 82°48′37″W / 40.40139°N 82.81028°W / 40.40139; -82.81028 (40.401341, -82.810382). It is considered to be a part of "Central Ohio."
According to the United States Census Bureau, the village has a total area of 0.2 square miles (0.5 km²), all of it land.