Marengo is a village in Morrow County, Ohio, United States.

According to the United States Census Bureau, the village has a total area of 0.17 square miles (0.44 km2), all of it land.

There were 148 housing units at an average density of 870.6 per square mile (336.1/km2).

25.6% of all households were made up of individuals, and 12.8% had someone living alone who was 65 years of age or older.

21.9% of all households were made up of individuals, and 5.3% had someone living alone who was 65 years of age or older.

About 3.5% of families and 9.2% of the population were below the poverty line, including 6.3% of those under the age of eighteen and none of those 65 or over.