Barnesville is a city in Clay County, Minnesota, United States. As of the 2000 census, the city had a total population of 2,173.
According to the United States Census Bureau, the city has a total area of 5.5 km2 (2.1 mi2). 5.4 km2 (2.1 mi2) of it is land and 0.1 km2 (0.04 mi2) of it is water. The total area is 0.94% water.