Marion County is the name of a number of counties in the United States of America, mostly named for General Francis Marion:
- Marion County, Alabama
- Marion County, Arkansas
- Marion County, Georgia
- Marion County, Illinois
- Marion County, Indiana
- Marion County, Iowa (Only possibly named for Francis Marion. It could have been named instead for a local pioneer)
- Marion County, Kansas (not named directly for General Francis Marion, but for Marion County, Ohio, and therefore only indirectly named for him)
- Marion County, Ohio