| Street | Postal Code | City | Prefecture |
|---|---|---|---|
| Oitis Street | 10672 | Athens | Attica |
| Oitylou Street | 11523 | Athens | Attica |
| Okeanidon Street | 11745 | Athens | Attica |
| Olenou Street | 11362 | Athens | Attica |
| Olofytou Street | 11142 | Athens | Attica |
| Olvias Street | 11142 | Athens | Attica |
| Olympiados Street | 11633 | Athens | Attica |
| Olympias Street | 10446, 11253 | Athens | Attica |
| Olympion Street | 11143 | Athens | Attica |
| Olympiou Dios Street | 10558 | Athens | Attica |
| Olympiou Georgaki Street | 11741 | Athens | Attica |
| Olympou Street | 10442 | Athens | Attica |
| Olynthou Street | 11143 | Athens | Attica |
| Olytsika Street | 16121 | Athens | Attica |
| Omirou Street | 10564, 10672 | Athens | Attica |
| Omol Theofilou Street | 11143 | Athens | Attica |
| Omonoias Square | 10431, 10551, 10552, 10564 | Athens | Attica |
| Onata Street | 10443 | Athens | Attica |
| Oreivasiou Street | 11476 | Athens | Attica |
| Oreon Street | 11523 | Athens | Attica |
| Orestiados Street | 11522 | Athens | Attica |
| Orestou Street | 11853 | Athens | Attica |
| Orfanidi Theodorou Street | 11141, 11142 | Athens | Attica |
| Orfanou Michail Street | 11471 | Athens | Attica |
| Orfeos Street | 11854, 11855 | Athens | Attica |
| Orias Street | 11522 | Athens | Attica |
| Origenous Street | 11471 | Athens | Attica |
| Orion Street | 11363 | Athens | Attica |
| Orionos Street | 11364 | Athens | Attica |
| Orkart David Street | 11741 | Athens | Attica |
| Orlandou Ioanni Street | 10445 | Athens | Attica |
| Orlof Street | 11741 | Athens | Attica |
| Orminiou Street | 11528 | Athens | Attica |
| Orologa Street | 11521 | Athens | Attica |
| Oromedontos Street | 11364 | Athens | Attica |
| Oropou Street | 11141, 11142 | Athens | Attica |
| Orou Street | 11632 | Athens | Attica |
| Ossis Street | 10444 | Athens | Attica |
| Ostrovou Street | 11363 | Athens | Attica |
| Othonos Street | 10557, 10563 | Athens | Attica |