There are 9 US Post Offices in Osceola County serving a total of 221,238 residents equating to 24,582 residents per post office. It's estimated that approximately 353,121 packages are handled across the 9 county post offices annually. Osceola County (/\u0252si\u02c8o\u028al\u0259/, o-si-OH-l\u0259) is a county located in the U.S. state of Florida. As of the 2010 census, the population was 268,685. Its county seat is Kissimmee. Osceola County is included in the Orlando-Kissimmee-Sanford, Fla. Metropolitan Statistical Area."