Barnhart is a census-designated place (CDP) in Jefferson County, Missouri, United States.

The land surrounding Barnhart originally belonged to Benjamin O'Fallon, who settled here with his family in 1834.

There were 2,003 housing units at an average density of 393.5 per square mile (151.9/km2).

12.6% of all households were made up of individuals, and 2.7% had someone living alone who was 65 years of age or older.

There were 1,999 housing units at an average density of 389.0 per square mile (150.2/km2).

11.2% of all households were made up of individuals, and 2.1% had someone living alone who was 65 years of age or older.

[9] A southwestern portion of the wider Barnhart area is assigned to the Dunklin R-V School District.

[10] The Windsor district previously ended at the eighth grade.