Flatwoods is a city within Greenup County, Kentucky. Flatwoods is considered a suburb of Ashland, Kentucky, in the United States, although Ashland itself is located in neighboring Boyd County. The population was 7,423 at the 2010 census, making Flatwoods the largest city in Greenup County. Flatwoods is a part of the Huntington-Ashland, WV-KY-OH, Metropolitan Statistical Area (MSA).