Barnett is a city in Morgan County, Missouri, United States. The population was 203 at the 2010 census.
Variant names were "Stone House" and "Barnetsville". A post office called Stone House was established in 1858, the name was changed to Barnettsville in 1875, and the name again changed to Barnett in 1880. The present name is after one Mr. Barnet, an early settler.
Jesse Ratcliff House was listed on the National Register of Historic Places in 1982.
Barnett is located at 38°22′37″N 92°40′29″W (38.377061, -92.674708).
According to the United States Census Bureau, the city has a total area of 0.27 square miles (0.70 km2), all land.
As of the census of 2010, there were 203 people, 81 households, and 56 families living in the city. The population density was 751.9 inhabitants per square mile (290.3/km2). There were 96 housing units at an average density of 355.6 per square mile (137.3/km2). The racial makeup of the city was 93.6% White, 3.4% Native American, 0.5% Asian, and 2.5% from two or more races. Hispanic or Latino of any race were 3.4% of the population.