| Official Name: | Ontario, Illinois |
| Settlement Type: | Unincorporated community |
| Pushpin Map: | Illinois#USA |
| Pushpin Label: | Ontario |
| Pushpin Label Position: | top |
| Subdivision Type: | Country |
| Subdivision Name: | United States |
| Subdivision Type1: | State |
| Subdivision Name1: | Illinois |
| Subdivision Type2: | County |
| Subdivision Name2: | Knox |
| Subdivision Type3: | Township |
| Subdivision Name3: | Ontario |
| Timezone: | Central (CST) |
| Utc Offset: | -6 |
| Timezone Dst: | CDT |
| Utc Offset Dst: | -5 |
| Elevation Ft: | 807 |
| Coordinates: | 41.0786°N -90.3075°W |
| Area Code: | 309 |
| Blank Name: | GNIS feature ID |
| Blank Info: | 423044 |
Ontario is an unincorporated community in Ontario Township, Knox County, Illinois, United States. Ontario is located at the junction of County Routes 6 and 35, 4miles north-northwest of Wataga.[1]