Gasconade County is a county located in the east-central portion of the U.S. state of Missouri. As of the 2010 census, the population was 15,222. The county seat is Hermann. The county was named after the Gasconade River.

The county is located on the south side of the Missouri River, which once served as the chief route of transportation in the state. It is located in the area known as the Missouri Rhineland. Because of its distinctive conditions, the Hermann area was designated an American Viticultural Area (AVA) in 1983. The southern part of the county is within the larger Ozark Highlands AVA, established in 1987.