9 cities
| City | County | 2025 Pop. ↓ |
|---|---|---|
| Orem | Utah County | 93,577 |
| Ogden | Weber County | 87,247 |
| Oakley | Summit County | 1,546 |
| Orangeville | Emery County | 1,284 |
| Oljato-Monument Valley | Apache County | 743 |
| Oak City | Millard County | 649 |
| Orderville | Kane County | 588 |
| Ophir | Tooele County | 51 |
| Oasis | Millard County | 38 |