Marion county is located in the western knobs region of Kentucky. It was formed in 1834 and named for General Francis Marion. The county seat is Lebanon.

Many early settlers were Catholic and the first Roman Catholic church in Kentucky was built in 1792 in what is now the town of Holy Cross. The Sisters of Loretto convent is also located in the county in Nerinx.

With a long history of whiskey production, Marion county still has a cooperage and is the home of Maker's Mark Distillery, at Burkes Spring outside Loretto.

The geographic center of Kentucky is in Marion county, about 3 miles northwest of Lebanon on KY 429.