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.

Utica is a city in the Mohawk Valley and the county seat of Oneida County, New York, United States. The tenth-most-populous city in New York State, its population was 65,283 in the 2020 U.S. Census. Located on the Mohawk River at the foot of the Adirondack Mountains, it is approximately 95 mi (153 km) west-northwest of Albany, 55 mi (89 km) east of Syracuse and 240 mi (386 km) northwest of New York City. Utica and the nearby city of Rome anchor the Utica–Rome Metropolitan Statistical Area comprising all of Oneida and Herkimer Counties.