| Rank | City | Contry Code | Population | Urban Population : |
| 6 | Osaka | JAP | 2647000 | 17592400 |
| 215 | Omdurman | SUD | 1670000 | 1670000 |
| 230 | Orlando | USA | 192600 | 1587500 |
| 302 | Oshogbo | NGR | 421000 | 1309900 |
| 307 | Okayama | JAP | 627900 | 1270100 |
| 336 | Omsk | RUS | 1137900 | 1148300 |
| 364 | Odesa | UKR | 990100 | 1109600 |
| 381 | Oklahoma City, | USA | 513900 | 1082000 |
| 387 | Ottawa | CAN | 348500 | 1070300 |
| 413 | Onitsha | NGR | 509500 | 1001000 |
| 420 | Ogbomosho | NGR | 726300 | 985600 |
| 493 | Ouagadougou | BUR | 839800 | 839800 |
| 527 | Oslo | NOR | 787400 | 787400 |
| 541 | Oran | ALG | 732000 | 772900 |
| 577 | Omaha | USA | 394300 | 722800 |
| 616 | Osasco | BRA | 669700 | 669700 |
| 635 | Ostrava | CZE | 318500 | 644000 |
| 656 | Oyo | NGR | 620400 | 620400 |
| 755 | Orenburg | RUS | 522200 | 538000 |
| 844 | Orumiyeh | IRA | 482600 | 482600 |
| 851 | Omiya | JAP | 476100 | 476100 |
| 885 | Okene | NGR | 444900 | 444900 |
| 901 | Oita | JAP | 428100 | 428100 |
| 921 | Oakland | USA | 411400 | 411400 |
| 986 | Olinda | BRA | 369500 | 369500 |
| 1047 | Oryol | RUS | 343700 | 343700 |
| 1051 | Oujda | MOR | 342900 | 342900 |
| 1192 | Oskemen | KAZ | 293600 | 293600 |
| 1225 | Okara | PAK | 286300 | 286300 |
| 1262 | Orsk | RUS | 273400 | 273400 |
| 1339 | Oaxaca | MEX | 257300 | 257300 |
| 1399 | Owo | NGR | 243000 | 243000 |
| 1506 | Ondo | NGR | 225800 | 225800 |
| 1533 | Oberhausen | GER | 221900 | 221900 |
| 1538 | Osh | KYR | 221300 | 221300 |
| 1546 | Oradea | ROM | 220100 | 220100 |
| 1573 | Odawara | JAP | 214900 | 214900 |
| 1661 | Oruro | BOL | 203100 | 203100 |
| 1671 | Olongapo | PHL | 202200 | 202200 |
| 1689 | Oviedo | SPA | 200700 | 200700 |
| 1798 | Owerri | NGR | 187600 | 187600 |
| 1824 | Oral | KAZ | 184500 | 184500 |
| 1876 | Osmaniye | TUR | 179500 | 179500 |
| 1903 | Olsztyn | POL | 176100 | 176100 |
| 1907 | Oxnard | USA | 175500 | 175500 |
| 1920 | Obihiro | JAP | 173900 | 173900 |
| 2005 | Oceanside | USA | 165800 | 165800 |
| 2019 | Osnabruck | GER | 164200 | 164200 |
| 2039 | Ontario | USA | 162700 | 162700 |
| 2042 | Osorno | CHL | 162100 | 162100 |
| 2097 | Oldenburg | GER | 156800 | 156800 |
| 2100 | Oyama | JAP | 156700 | 156700 |
| 2145 | Okpoko | NGR | 152900 | 152900 |
| 2176 | Overland Park, | USA | 151000 | 151000 |
| 2180 | Omuta | JAP | 150700 | 150700 |
| 2253 | Odense | DEN | 145300 | 145300 |
| 2260 | Oshawa | CAN | 144800 | 144800 |
| 2353 | Oakville | CAN | 138400 | 138400 |
| 2378 | Otukpo | NGR | 136800 | 136800 |
| 2446 | Orange | USA | 132700 | 132700 |
| 2449 | Olmaliq | UZB | 132300 | 132300 |
| 2467 | Ordu | TUR | 131300 | 131300 |
| 2496 | Opole | POL | 129100 | 129100 |
| 2521 | Ocumare | VEN | 127500 | 127500 |
| 2539 | Odincovo | RUS | 126500 | 126500 |
| 2590 | Orehovo-Zuyevo | RUS | 124300 | 124300 |
| 2594 | Orsa | BLR | 124100 | 124100 |
| 2614 | Oulu | FIN | 122900 | 122900 |
| 2620 | Obuasi | GHA | 122600 | 122600 |
| 2646 | Oxford | UK | 121700 | 121700 |
| 2654 | Orizaba | MEX | 121300 | 121300 |
| 2754 | Offenbach | GER | 115600 | 115600 |
| 2833 | Orléans | FRA | 112500 | 112500 |
| 2844 | Oktyabrskiy | RUS | 112100 | 112100 |
| 2925 | Ourense | SPA | 109200 | 109200 |
| 2953 | Obninsk | RUS | 108100 | 108100 |
| 3020 | Offa | NGR | 105700 | 105700 |
| 3063 | Oldham | UK | 103700 | 103700 |
| 3085 | Olomouc | CZE | 103100 | 103100 |
| 3129 | Ovalle | CHL | 101100 | 101100 |
| 3140 | Okigwe | NGR | 100700 | 100700 |
| 3247 | Orebro | SWE | 95200 | 95200 |
| 3256 | Odessa | USA | 94400 | 94400 |
| 3263 | Olathe | USA | 94200 | 94200 |
| 3308 | Osijek | CRO | 90500 | 90500 |
| 3350 | Orem | USA | 87200 | 87200 |
| 3439 | Ogden | USA | 79900 | 79900 |
| 3615 | Oshkosh | USA | 63800 | 63800 |
| 3643 | Ouahigouya | BUR | 61800 | 61800 |
| 3758 | Owensboro | USA | 54900 | 54900 |
| 3862 | Ocala | USA | 47600 | 47600 |
| 3920 | Olympia | USA | 43600 | 43600 |
| 4075 | Oshakati | NAM | 30300 | 30300 |
| 4093 | Oyem | GAB | 28900 | 28900 |
| 4106 | Oakengates-Donnington | UK | 28000 | 28000 |
| 4160 | Owando | CNG | 22800 | 22800 |
| 4166 | Ouesso | CNG | 22200 | 22200 |
| 4180 | Oranjestad | CRB-ARU | 20700 | 20700 |
| 4220 | Orange Walk | BLZ | 14100 | 14100 |
| 4245 | Onchan | MAN | 9300 | 9300 |
| 4350 | Oranjestad | CRB-NAN | 2300 | 2300 |
| 4394 | Old Road | CRB-SKN | 1000 | 1000 |
| 4440 | Ooma | KIR | 250 | 250 |
| 4476 | Ollei | PLU | 110 | 110 |
| 4484 | Oikul | PLU | 70 | 70 |