22 cities
| City | County | 2025 Pop. ↓ |
|---|---|---|
| Irvine | Orange County | 321,241 |
| Inglewood | Los Angeles County | 101,618 |
| Indio | Riverside County | 95,474 |
| Imperial Beach | San Diego County | 25,434 |
| Imperial | Imperial County | 22,510 |
| Isla Vista | Santa Barbara County | 12,628 |
| Ione | Amador County | 9,532 |
| Interlaken | Monterey County | 8,218 |
| Indian Wells | Riverside County | 5,041 |
| Ivanhoe | Tulare County | 4,288 |
| Idyllwild-Pine Cove | Riverside County | 3,395 |
| Inverness | Marin County | 1,510 |
| Irwindale | Los Angeles County | 1,457 |
| Independence | Inyo County | 895 |
| Inyokern | Kern County | 878 |
| Isleton | Sacramento County | 777 |
| Indianola | Humboldt County | 690 |
| Indio Hills | Riverside County | 513 |
| Iron Horse | Plumas County | 448 |
| Industry | Los Angeles County | 254 |
| Igo | Shasta County | 119 |
| Idlewild | Tulare County | 60 |