| Honiara Oldbrook | United Kingdom Time | 11:00 |
| Honiara Okehampton | United Kingdom Time | 11:00 |
| Honiara Okeechobee | Eastern Time | 16:00 |
| Honiara Oka | Eastern Time | 16:00 |
| Honiara Ojai | Pacific Time | 19:00 |
| Honiara Ohio | Eastern Time | 16:00 |
| Honiara Ohain | Central European Time | 10:00 |
| Honiara Oia | Eastern European Time | 09:00 |
| Honiara Ogunquit | Eastern Time | 16:00 |
| Honiara Ogmore Vale | United Kingdom Time | 11:00 |
| Honiara Ochsenfurt | Central European Time | 10:00 |
| Honiara Ocho Rios | Eastern Time | 16:00 |
| Honiara Ocean Grove | Eastern Australia Time | 00:00 |
| Honiara Ocean Isle Beach | Eastern Time | 16:00 |
| Honiara Ocean Shores | Pacific Time | 19:00 |
| Honiara Ocean View | Eastern Time | 16:00 |
| Honiara Oceana | Eastern Time | 16:00 |
| Honiara Ocaña | Central European Time | 10:00 |
| Honiara Odense | Central European Time | 10:00 |
| Honiara Odeceixe | Western European Time | 11:00 |
| Honiara Oddanchatram | India Standard Time | 05:30 |
| Honiara Oeiras | Western European Time | 11:00 |
| Honiara Officer | Eastern Australia Time | 00:00 |
| Honiara Oberbüren | Central European Time | 10:00 |
| Honiara Oberkorn | Central European Time | 10:00 |
| Honiara Oberlin | Eastern Time | 16:00 |
| Honiara Obernberg am Brenner | Central European Time | 10:00 |
| Honiara Oaxaca | Central Time | 17:00 |
| Honiara Oamaru | New Zealand Time | -02:00 |
| Honiara Oberstaufen | Central European Time | 10:00 |
| Honiara Obertrubach | Central European Time | 10:00 |
| Honiara Oberhausen-Rheinhausen | Central European Time | 10:00 |
| Honiara Oberwesel | Central European Time | 10:00 |
| Honiara Oak Bluffs | Eastern Time | 16:00 |
| Honiara Oak Brook | Central Time | 17:00 |
| Honiara Oakdale | United Kingdom Time | 11:00 |
| Honiara Oakdale | Pacific Time | 19:00 |
| Honiara Oakham | United Kingdom Time | 11:00 |
| Honiara Oakhurst | Pacific Time | 19:00 |
| Honiara Oaklands Park | Central Australia Time | 00:30 |
| Honiara Oak Park Heights | Central Time | 17:00 |
| Honiara Oak Hill | Eastern Time | 16:00 |
| Honiara Oak Island | Eastern Time | 16:00 |
| Honiara Owego | Eastern Time | 16:00 |
| Honiara Oviglio | Central European Time | 10:00 |
| Honiara Overo | Central European Time | 10:00 |
| Honiara Oulton | United Kingdom Time | 11:00 |
| Honiara Ottignies-Louvain-la-Neuve | Central European Time | 10:00 |
| Honiara Ottawa | Eastern Time | 16:00 |
| Honiara Oud-Heverlee | Central European Time | 10:00 |