Olney
- County:
- Richland County
- County Seat:
- Yes
- Area (mi²):
- 6.931
- State:
- Illinois
Olney is a city located in Richland County, Illinois. Olney has a 2026 population of 8,431. It is also the county seat of Richland County. Olney is currently declining at a rate of -0.93% annually and its population has decreased by -2.99% since the most recent census, which recorded a population of 8,691 in 2020.