Ottawa County is a county located in the northeastern corner of the U.S. state of Oklahoma. As of the 2020 census, the population was 30,285. Its county seat is Miami. The county was named for the Ottawa Tribe of Oklahoma. It is also the location of the federally recognized Modoc Nation and the Quapaw Nation, which is based in Quapaw. Ottawa County comprises the Miami, OK Micropolitan Statistical Area, which is included in the Joplin-Miami, MO-OK Combined Statistical Area.