| City | 2026 Pop. ↓ |
|---|---|
| Oberhausen | 215,176 |
| Oldenburg (Oldb) | 180,555 |
| Osnabrueck | 167,224 |
| Offenbach am Main | 136,095 |
| Offenburg | 63,776 |
| Oranienburg | 50,684 |
| Oberursel (Taunus) | 47,260 |
| Ostfildern | 40,002 |
| Oer-Erkenschwick | 31,761 |
| Oelde | 30,560 |
| Osterholz-Scharmbeck | 29,658 |
| Olching | 27,303 |
| Overath | 26,718 |
| Oehringen | 26,031 |
| Obertshausen | 25,854 |
| Olpe | 24,739 |
| Ottobrunn | 23,359 |
| Osterode am Harz | 21,503 |
| Ochtrup | 20,917 |
| Oberkirch | 20,068 |
| Oschersleben (Bode) | 19,428 |
| Oberasbach | 17,850 |
| Oerlinghausen | 17,273 |
| Oyten | 16,686 |
| Odenthal | 15,950 |
| Ober-Ramstadt | 15,217 |
| Oberndorf am Neckar | 15,192 |
| Olsberg | 14,660 |
| Oschatz | 14,319 |
| Ottweiler | 14,087 |
| Obersulm | 13,668 |
| Oestringen | 13,645 |
| Olfen | 13,546 |
| Ottersberg | 13,193 |
| Oberhaching | 13,176 |
| Oebisfelde-Weferlingen | 12,934 |
| Osterhofen | 12,601 |
| Ostrhauderfehn | 12,332 |
| Oftersheim | 12,303 |
| Oberkraemer | 12,188 |
| Oberderdingen | 12,032 |
| Ostbevern | 11,929 |
| Oberschleissheim | 11,864 |
| Oestrich-Winkel | 11,426 |
| Ochsenfurt | 11,360 |
| Oelsnitz/Erzgeb. | 10,813 |
| Osterwieck | 10,802 |
| Oelsnitz/Vogtl. | 9,824 |