| Name | What | Region | Country | Lat | Long | Elev ft. | Pop est |
|---|---|---|---|---|---|---|---|
| Odogno | city | Ticino | Switzerland | 46.08 | 8.97 | 2654 | 27783 |
| Oggio | city | Ticino | Switzerland | 46.07 | 8.99 | 2637 | 33498 |
| Olivella | city | Ticino | Switzerland | 45.93 | 8.93 | 866 | 29564 |
| Olivone | city | Ticino | Switzerland | 46.53 | 8.94 | 4311 | 905 |
| Opera castellana del Castello di Croglio | city | Ticino | Switzerland | 45.99 | 8.84 | 1906 | 28152 |
| Opera castellano del Castello di San Martino | city | Ticino | Switzerland | 45.98 | 8.96 | 830 | 75677 |
| Orbello | city | Ticino | Switzerland | 46.13 | 8.93 | 3349 | 15519 |
| Origlio | city | Ticino | Switzerland | 46.05 | 8.95 | 2034 | 65655 |
| Orino | city | Ticino | Switzerland | 45.98 | 8.91 | 1669 | 63126 |
| Orsà ira di Fuori | city | Ticino | Switzerland | 46.56 | 8.92 | 5029 | 574 |
| Osco | city | Ticino | Switzerland | 46.49 | 8.78 | 3349 | 3011 |
| Osnaga | city | Ticino | Switzerland | 46.08 | 9.03 | 3464 | 7129 |
| Osogna | city | Ticino | Switzerland | 46.31 | 8.99 | 2677 | 7087 |