Middlebourne is a town in Tyler County, West Virginia, United States. The population was 870 at the 2000 census. It is the county seat of Tyler County. The town was established by an enactment of the Virginia General Assembly in 1813. Two explanations have been given for the name of the town: One is that it was located halfway between Pennsylvania and a series of salt wells along the Kanawha River upstream of Charleston; the other is that it is located midway between the source and the mouth of Middle Island Creek, which flows through the town.