Morrow County is a county located in the central portion of the U.S. state of Ohio. As of the 2020 census, the population was 34,950. Its county seat is Mount Gilead. The county was organized in 1848 from parts of four neighboring counties and named for Jeremiah Morrow who was the Governor of Ohio from 1822 to 1826. Shawnee people used the area for hunting purposes before white settlers arrived in the early 19th century. Morrow County is included in the Columbus, OH Metropolitan Statistical Area. In 2010, the center of population of Ohio was located in Morrow County, near the village of Marengo. Morrow County's historic World War I Victory Shaft, unique in the United States, is located in the center of downtown Mount Gilead. Other areas interesting to the tourist include: Mount Gilead State Park; Amish farms and businesses near Johnsville and Chesterville; the Mid-Ohio Sports Car Course near Steam Corners; the rolling Allegheny foothills of eastern Morrow County; the site of the birthplace of President Warren G. Harding near Blooming Grove; the site of the former Ohio Central College in Iberia; the early 19th-century architecture of buildings in Chesterville, Ohio; the Revolutionary War Soldiers' Memorial in Mount Gilead; the Civil War monument in Cardington; and the mid-19th-century architecture of the Morrow County Courthouse and Old Jail in Mount Gilead.

According to the U.S. Census Bureau, the county has a total area of 407 square miles (1,050 km²), of which 406 square miles (1,050 km²) is land and 1.1 square miles (2.8 km²) (0.3%) is water. Morrow County is considered to be a part of "Mid Ohio."

Ossing Run is a tributary of Shaw Creek that flows through Morrow County.

As of the 2020 census, the county had a population of 34,950 and a median age of 42.7 years. 23.0% of residents were under the age of 18 and 18.6% of residents were 65 years of age or older, while there were 101.2 males for every 100 females and 100.1 males for every 100 females age 18 and over.

The racial makeup of the county was 94.2% White, 0.5% Black or African American, 0.3% American Indian and Alaska Native, 0.3% Asian, <0.1% Native Hawaiian and Pacific Islander, 0.7% from some other race, and 4.1% from two or more races. Hispanic or Latino residents of any race comprised 1.7% of the population.

<0.1% of residents lived in urban areas, while 100.0% lived in rural areas.

There were 13,334 households in the county, of which 30.5% had children under the age of 18 living in them. Of all households, 56.3% were married-couple households, 16.8% were households with a male householder and no spouse or partner present, and 19.2% were households with a female householder and no spouse or partner present. About 22.7% of all households were made up of individuals and 10.5% had someone living alone who was 65 years of age or older.

There were 14,472 housing units, of which 7.9% were vacant. Among occupied housing units, 80.5% were owner-occupied and 19.5% were renter-occupied. The homeowner vacancy rate was 1.7% and the rental vacancy rate was 5.6%.