Oneida is a city in Knox County, Illinois, United States.

According to the 2010 census, Oneida has a total area of 0.76 square miles (1.97 km2), all land.

There were 308 housing units at an average density of 424.3 per square mile (163.8/km2).

24.1% of all households were made up of individuals, and 11.9% had someone living alone who was 65 years of age or older.

Out of the total population, 10.5% of those under the age of 18 and 2.2% of those 65 and older were living below the poverty line.