Ontario County is a county in the U.S. State of New York. As of the 2020 census, the population was 112,458. The county seat is Canandaigua. The county is part of the Finger Lakes region of the state.

Canandaigua is a city in Ontario County, New York, United States. Its population was 10,545 at the 2010 census. It is the county seat of Ontario County; some administrative offices are at the county complex in the adjacent town of Hopewell.