| Oakley, Aaron | Swindon (ENG) / Wales U19 |  Wales | Defender |
| Oancea, Evgheni | Moldova U17 |  Moldova | Midfield |
| Oar, Tomas | Utrecht (NED) |  Australia | Forward |
| Obadă, Cristian | Moldova FUT | Moldova | Forward |
| Obadeyi, Tope | Rio Ave (POR) |  England | Forward |
| Obasi, Chinedu | Schalke (GER) |  Nigeria | Forward |
| Obayomi, Ibrahim | Marítimo (POR) | Nigeria | |
| Obeng, Curtis | Swansea (WAL) | England | Defender |
| Oberemko, Andriy | Metalurh Zaporizhya (UKR) |  Ukraine | Midfield |
| Oberhauser, David | Ajaccio (FRA) |  France | Midfield |
| Oberressl, Carmen | Austria WU19 |  Austria | Defender |
| Obertan, Gabriel | Newcastle (ENG) | France | Midfield |
| Oberweis, Marc | Luxembourg |  Luxembourg | Goalkeeper |
| Obi, Joel | Internazionale (ITA) | Nigeria | Midfield |
| Obiang, Pedro Mba | Sampdoria (ITA) / Spain U21 |  Spain | Midfield |
| Obin, Jérémy | Valenciennes (FRA) | France | Defender |
| Obinna, Victor | Lokomotiv Moskva (RUS) | Nigeria | Forward |
| Obita, Jordan | Reading (ENG) | England | Midfield |
| Oblak, Jan | Rio Ave (POR) / Slovenia / Slovenia U21 |  Slovenia | Goalkeeper |
| Obradović, Milan | Arsenal Kyiv (UKR) |  Serbia | Defender |
| Obradović, Ivan | Zaragoza (ESP) | Serbia | Defender |
| Obraniak, Ludovic | Bordeaux (FRA) / Poland |  Poland | Forward |
| O'Brien, Michelle | Republic of Ireland WOCO |  Republic of Ireland | Forward |
| O'Brien, Joey | West Ham (ENG) / Republic of Ireland | Republic of Ireland | Midfield |
| Occean, Olivier | Eintracht Frankfurt (GER) |  Canada | Forward |
| Ochoa, Guillermo | Ajaccio (FRA) |  Mexico | Goalkeeper |
| Ochoa, Ane | Spain WU19 | Spain | Goalkeeper |
| Ochs, Patrick | Hoffenheim (GER) |  Germany | Defender |
| O'Connell, Ciara | Republic of Ireland WU19 | Republic of Ireland | Midfield |
| O'Connell, Jack | York (ENG) / England U19 | England | Defender |
| O'Connor, Amy | Republic of Ireland WU17 | Republic of Ireland | Midfield |
| Oczipka, Bastian | Eintracht Frankfurt (GER) | Germany | Defender |
| O'Dea, Darren | Celtic (SCO) / Republic of Ireland | Republic of Ireland | Defender |
| Odebrecht, Viola | Wolfsburg (GER) / Germany WOCO | Germany | Midfield |
| Ødegård, Magnar | Norway U21 |  Norway | Defender |
| Odehnalová, Adéla | Czech Republic WOCO |  Czech Republic | Midfield |
| Odelius, Kim | Brommapojkarna (SWE) |  Sweden | |
| Odemwingie, Peter | West Brom (ENG) | Nigeria | Forward |
| Odeurs, Justien | Belgium WU17 |  Belgium | Goalkeeper |
| Odibe, Michael | Arsenal Kyiv (UKR) | Nigeria | Defender |
| Ódinsdóttir, Gudný Björk | Kristianstads (SWE) / Iceland WOCO |  Iceland | Midfield |
| Odjidja, Vadis | Club Brugge (BEL) | Belgium | Midfield |
| Odoi, Denis | Anderlecht (BEL) | Belgium | Defender |
| Odonkor, David | Hoverla (UKR) | Germany | Forward |
| O'Donnell, Stephen | Dundee (SCO) |  Scotland | |
| O'Donnell, Hayley | Northern Ireland WU19 |  Northern Ireland | Midfield |
| Odysseos, Odysseas | Omonia (CYP) / Cyprus FUT |  Cyprus | Goalkeeper |
| Oehri, Yves | Vaduz (LIE) / Liechtenstein |  Liechtenstein | Midfield |
| Oehri, Marco | Liechtenstein U17 | Liechtenstein | Defender |
| Oehrl, Torsten | Augsburg (GER) | Germany | Forward |
