Martin County is a county located in the U.S. state of Kentucky. As of the 2010 census, the population was 12,929. Its county seat is Inez. The county was founded in 1870 and is named for Congressman John Preston Martin. It is a prohibition or dry county, which means that alcohol sales are prohibited in all areas of the county.GeographyAccording to the U.S. Census Bureau, the county has a total area of, of which is land and (0.4%) is water. The county's eastern border is formed by the Tug Fork of the Big Sandy River.Adjacent countiesLawrence County (northwest)Wayne County, West Virginia (northeast)Mingo County, West Virginia (southeast)Pike County (south)Floyd County (southwest)Johnson County (west)