| Adam Obert | d | SLV | 2023/24 | 0 | 0 | Cagliari | | | |
| Fabio Occhioni | c | ITA | 2020/21 | 1 | 0 | Olbia | | | |
| Riccardo Oddi | d | ITA | 2021/22 | 1 | 0 | Fiorenzuola, Trento | | | |
| Moses Odjer | c | GHA | 2022/23 | 0 | 0 | Foggia, Livorno | | | |
| Raphael Odogwu | a | ITA - NIG | 2021/22 | 2 | 1 | Südtirol | | | |
| Emanuele Offidani | c | ITA - CAN | 2018/19 | 0 | 0 | Cuneo | | | |
| Daniel Offredi | p | ITA | 2021/22 | 2 | -2 | Albino Leffe, Triestina | | | |
| Roberto Ogunseye | a | ITA - NIG | 2018/19 | 6 | 2 | Olbia, Foggia, Cesena, Perugia | | | |
| Stefano Okaka | a | ITA | 2025/26 | 1 | 0 | Ravenna | | | |
| Filippo Oliana | d | ITA | 2018/19 | 3 | 0 | Albissola, Sestri Levante | | | |
| Fabricio Olivera | d | ITA - BRA | 2021/22 | 1 | 0 | Fiorenzuola | | | |
| Daniele Olivieri | c | ITA | 2021/22 | 0 | 0 | Legnago | | | |
| Edoardo Olivieri | d | ITA | 2022/23 | 1 | 0 | Virtus Verona, Campobasso | | | |
| Bob Omoregbe | a | ITA - NIG | 2023/24 | 1 | 0 | Sestri Levante | | | |
| Edoardo Oneto | a | ITA | 2021/22 | 2 | 0 | Fiorenzuola | | | |
| Mihael Onișa | c | ROM | 2022/23 | 0 | 0 | Piacenza | | | |
| Luca Onofri | d | ITA | 2018/19 | 0 | 0 | Arzachena | | | |
| Onofri | d | ITA | 2025/26 | 0 | 0 | Forlì | | | |
| Vincenzo Onofrietti | c | ITA - GER | 2024/25 | 0 | 0 | Team Altamura | | | |
| Raul Oprut | d | ROM | 2018/19 | 3 | 0 | Albissola | | | |
| Marcelo Orellana | c | ITA - CIL | 2025/26 | 1 | 0 | Ternana | | | |
| Alessandro Orfei | a | ITA | 2023/24 | 2 | 0 | Spal | | | |
| Riccardo Ori | d | ITA | 2025/26 | 1 | 0 | Renate | | | |
| Gaetano Oristanio | c | ITA | 2023/24 | 0 | 0 | Cagliari | | | |
| Francesco Orlando | a | ITA | 2024/25 | 2 | 1 | Foggia | | | |
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