| Okan Derıcı | Galatasaray (TUR) |  Turquía | Delantero |
| O'Kane, Eunan | Bournemouth (ENG) / Northern Ireland U21 / Republic of Ireland U21 |  República de Irlanda | |
| Okay Yokuşlu | Kayserispor (TUR) / Turkey U19 | Turquía | Centrocampista |
| Okazaki, Shinji | Stuttgart (GER) |  Japón | Centrocampista |
| Okine, Priscilla | Spartak Subotica (SRB) |  Ghana | Defensa |
| Okore, Jores | Nordsjælland (DEN) / Denmark U21 / Denmark |  Dinamarca | Defensa |
| Okoronkwo, Isaak | Rostov (RUS) |  Nigeria | Defensa |
| Okotie, Rubin | Sturm (AUT) |  Austria | Delantero |
| Okoyino Da Mbabi, Célia | Bad Neuenahr (GER) / Germany WOCO |  Alemania | Delantero |
| Okriashvili, Tornike | Illychivets (UKR) / Georgia U21 / Georgia |  Georgia | Centrocampista |
| Oksanen, Jaakko | Finland U17 |  Finlandia | Delantero |
| Okulewicz, Anna | Poland WU17 |  Polonia | Portero |
| Olabarrieta, Amaia | Athletic (ESP) / Spain WOCO |  España | Centrocampista |
| Olabe, Roberto | Spain U17 | España | Centrocampista |
| Óladóttir, Gudmunda | Iceland WOCO / Iceland WU19 |  Islandia | Delantero |
| Ólafsdóttir, Laufey | Valur (ISL) / Iceland WOCO | Islandia | Centrocampista |
| Olafsdóttir, Doris | Klaksvík (FRO) / Faroe Islands WOCO |  Islas Feroe | Defensa |
| Olafsdóttir, Alda | Iceland WU17 | Islandia | Delantero |
| Ólafsson, Árni | ÍA (ISL) / Iceland U21 | Islandia | Portero |
| Olah, Adrian | Turnu Severin (ROU) |  Rumanía | Centrocampista |
| Olăr, Corina | Olimpia Cluj (ROU) / Romania WOCO | Rumanía | Defensa |
| Olawale Ojuola, Noah | Midtjylland (DEN) | Nigeria | Defensa |
| Olberdam | Marítimo (POR) |  Brasil | Centrocampista |
| Olcan Adın | Trabzonspor (TUR) | Turquía | Centrocampista |
| O'leary, Ryan | Kilmarnock (SCO) | República de Irlanda | Defensa |
| Oleksy, Paweł | Piast (POL) / Poland U21 | Polonia | Defensa |
| Olesen, Allan | Åtvidaberg (SWE) | Dinamarca | Defensa |
| Olesen, Casper | Denmark U17 | Dinamarca | Delantero |
| Olić, Ivica | Wolfsburg (GER) / Croatia |  Croacia | Delantero |
| Oliech, Dennis | Ajaccio (FRA) |  Kenya | Delantero |
| Oliinyk, Iaroslav | Ukraine U21 |  Ucrania | Defensa |
| Olijve, Frank | Zwolle (NED) |  Holanda | Centrocampista |
| Olimpa, Kevin | Bordeaux (FRA) |  Francia | Portero |
| Öling, Ria | PK-35 (FIN) / Finland WU19 | Finlandia | Delantero |
| Oliseh, Isaac | Midtjylland (DEN) | Nigeria | Centrocampista |
| Oliva, Oriol | Andorra U21 |  Andorra | Portero |
| Oliva, Petr | Chrudim (CZE) / Czech Republic FUT |  República Checa | Defensa |
| Oliynyk, Denys | Dnipro (UKR) | Ucrania | Centrocampista |
| Olkowski, Paweł | Górnik (POL) / Poland U21 | Polonia | Defensa |
| Olsen, Súni | Faroe Islands | Islas Feroe | Centrocampista |
| Olsen, Malene | Brøndby (DEN) / Denmark WOCO | Dinamarca | Defensa |
| Olsen, Danny | Midtjylland (DEN) | Dinamarca | Centrocampista |
| Olsen, Anna | Brøndby (DEN) | Dinamarca | Portero |
| Olsen, Klæmint | Faroe Islands U21 / Faroe Islands | Islas Feroe | Delantero |
| Olsen, Adelheid | Klaksvík (FRO) | Islas Feroe | Defensa |
| Olsen, Teitur | Faroe Islands U19 | Islas Feroe | Defensa |
| Olsen, Patrick | Internazionale (ITA) / Denmark U19 | Dinamarca | Centrocampista |
| Olsen, Dania | Faroe Islands WU19 | Islas Feroe | Delantero |
| Olsen, Meinhard | Faroe Islands U17 | Islas Feroe | Delantero |
| Olsen, Robin | Malmö (SWE) | Dinamarca | Portero |
