Vernon is a town in Vernon Township, Jennings County, Indiana, United States. It is the county seat of Jennings County. With a population of 318 in the 2010 census, it is the smallest town with that designation in the state of Indiana, lying just south of the much larger North Vernon. It is nearly surrounded by the Muscatatuck River. Vernon has the only elected mayor of a town in the state of Indiana and the only elected town marshal. As of 2010, Dan Wright is Mayor and Britt Burgmeier is the Marshal.
The Vernon Historic District is on the National Register of Historic Places and is the host of many firsts in the state.
It was also the home of Indiana's fourth state park, now called Muscatatuck County Park.