Seminole County is a county located in the U.S. state of Oklahoma. As of the 2020 census, the population was 23,556. Its county seat is Wewoka. Most of the county was a reservation for the Seminole Nation of Oklahoma which still retains jurisdiction over some land in the county. A small portion of land at the eastern end of the county belonged to the Muscogee N…Seminole County is a county located in the U.S. state of Oklahoma. As of the 2020 census, the population was 23,556. Its county seat is Wewoka. Most of the county was a reservation for the Seminole Nation of Oklahoma which still retains jurisdiction over some land in the county. A small portion of land at the eastern end of the county belonged to the Muscogee Nation.