Kissimmee ( kih-SIM-ee) is the largest city and county seat of Osceola County, Florida, United States. As of the 2020 census, the population was 79,226. It is a Principal City of the Orlando-Kissimmee-Sanford, Florida, Metropolitan Statistical Area, which had a 2020 population of 2,673,376. The Census Bureau defines an urban area with Kissimmee as the principal city, which is separated from the Orlando urban area. The Kissimmee–St. Cloud, FL urban area had a 2020 population of 418,404, making it the 100th largest in the United States.