| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Oakley | city | Idaho | United States | 42.24 | -113.88 | 4589 | |
| Obsidian | city | Idaho | United States | 44.08 | -114.85 | 6797 | |
| Oden | city | Idaho | United States | 48.32 | -116.41 | 2509 | |
| Ola | city | Idaho | United States | 44.18 | -116.29 | 3349 | |
| Old Beaver | city | Idaho | United States | 44.41 | -112.20 | 5980 | |
| Old Fort | city | Idaho | United States | 44.81 | -116.16 | 5029 | |
| Old Golden | city | Idaho | United States | 45.79 | -115.65 | 5029 | |
| Old Williamsburg (historical) | city | Idaho | United States | 42.94 | -111.34 | 6771 | |
| Oldtown | city | Idaho | United States | 48.18 | -117.04 | 2509 | |
| Olsen | city | Idaho | United States | 43.29 | -112.62 | 4599 | |
| Olsons | city | Idaho | United States | 47.00 | -115.13 | 5869 | |
| Omega | city | Idaho | United States | 47.33 | -116.48 | 2775 | |
| Omill | city | Idaho | United States | 46.49 | -115.93 | 3349 | |
| Onaway | city | Idaho | United States | 46.93 | -116.89 | 2598 | |
| Ora | city | Idaho | United States | 44.09 | -111.53 | 5196 | |
| Orchard | city | Idaho | United States | 43.31 | -116.03 | 3349 | |
| Orchard Homes (historical) | city | Idaho | United States | 46.60 | -116.73 | 1669 | |
| Oreana | city | Idaho | United States | 43.05 | -116.40 | 2798 | |
| Oro Fino (historical) | city | Idaho | United States | 46.48 | -115.80 | 3349 | |
| Orofino | city | Idaho | United States | 46.48 | -116.26 | 1197 | |
| Orogrande | city | Idaho | United States | 45.71 | -115.54 | 5029 | |
| Orvin | city | Idaho | United States | 43.53 | -112.01 | 5029 | |
| Osburn | city | Idaho | United States | 47.51 | -116.00 | 2598 | |
| Osgood | city | Idaho | United States | 43.57 | -112.10 | 5029 | |
| Outlet Bay | city | Idaho | United States | 48.49 | -116.89 | 3349 | |
| Ovid | city | Idaho | United States | 42.29 | -111.40 | 5925 | |
| Owinza | city | Idaho | United States | 42.90 | -114.06 | 4189 | |
| Owyhee | city | Idaho | United States | 43.42 | -116.20 | 3349 | |
| Owyhee Heights | city | Idaho | United States | 43.62 | -116.99 | 2509 | |
| Oxford | city | Idaho | United States | 42.26 | -112.02 | 5029 |