Bladensburg is a census-designated place on the border between the Clay and Jackson Townships of Knox County, Ohio, USA. Although it is unincorporated, it has a post office, with the ZIP code of 43005. It lies along State Route 541 east of Martinsburg.
Bladensburg was originally spelled Bladensburgh, and under the latter name was laid out in 1833. A post office has been in operation at Bladensburg(h) since 1834.
Bladensburg is the former home of East Knox Elementary School.
Bladensburg is also home to the Bladensburg Volunteer Fire Department, with 42 volunteer firefighters. It is the main station for the Bladensburg Joint Fire District.
Bladensburg is the home of a popular annual Christmas parade, which has been held since 1971.