Neosho (originally or ) is the most populous city and the county seat of Newton County, in the U.S. state of Missouri. With a population of 12,590 as of the 2020 census, the city is a part of the Joplin metropolitan area, a region with an estimated 176,849 residents, as of 2011. Neosho lies on the western edge of the Ozarks, in the far southwest of the state.