Oneida is a city in Knox County, Illinois, United States. The population was 750 at the 2000 census. It is part of the Galesburg Micropolitan Statistical Area.
Oneida is located at 41°4′28″N 90°13′29″W / 41.07444°N 90.22472°W / 41.07444; -90.22472 (41.074579, -90.224730).
According to the United States Census Bureau, the city has a total area of 0.7 square miles (1.9 km²), all of it land.