Martin County is a county located in the U.S. state of Florida. Its county seat is Stuart. Martin County was created in 1925 and was named for John W. Martin, Governor of Florida from 1925 to 1929. Martin County is part of the Port St. Lucie-Fort Pierce Metropolitan Statistical Area. Martin County has a total area of approximately 753 square miles of which 74% is land and 26% water. As of the 2000 census, there were 126,731 people, 55,288 households, and 36,213 families residing in Martin County, FL.