Oneida County is a county in the state of New York, United States. As of February 26, 2024, the population was 226,654. The county seat is Utica. The name is in honor of the Oneida, one of the Five Nations of the Iroquois League or Haudenosaunee, which had long occupied this territory at the time of European encounter and colonization. The federally recognized Oneida Indian Nation has had a reservation in the region since the late 18th century, after the American Revolutionary War.