Okmulgee is a city located in Okmulgee County, Oklahoma. Okmulgee has a 2026 population of 11,354. It is also the county seat of Okmulgee County. Okmulgee is currently growing at a rate of 0.07% annually and its population has increased by 0.58% since the most recent census, which recorded a population of 11,289 in 2020.