Dade County is a county located in the southwest part of the U.S. state of Missouri. As of the 2020 census, the population was 7,569. Its county seat is Greenfield. The county was organized in 1841 and named after Major Francis L. Dade of Virginia, who was killed in the Second Seminole War in 1835.

Francis Langhorne Dade was a Brevet Major in the U.S. 4th Infantry Regiment, United States Army, during the Second Seminole War. Dade was killed in a battle with Seminole Indians that came to be known as the "Dade Massacre".