| Oleggio Magic Basket | — | Oleggio | — | — |
| Olimpia Basket Matera | — | Matera | 1960 | — |
| Olimpia Basket Pistoia | — | Pistoia | 1965 | — |
| Olimpia Milano | Serie A | Milan | 1936 | Forum di Milano |
| Olympia 68 Basketball | — | Reggio Calabria | — | — |
| Oratorio Elmas | — | — | — | — |
| Orlandina Basket | — | Capo d'Orlando | 1978 | PalaFantozzi |
| Orlando Magic | National Basketball Association | Orlando | 1989 | Amway Arena, Kia Center |
| Orzi Basket | — | Orzinuovi | 1964 | — |
| Pallacanestro Aurora Desio | — | Desio | 1994 | — |
| Pallacanestro Biella | — | Biella | 1994 | BiellaForum |
| Pallacanestro Broni 93 | — | — | — | — |
| Pallacanestro Chieti | — | Chieti | 1989 | — |
| Pallacanestro Don Bosco Livorno | — | — | — | — |
| Pallacanestro Femminile Costone | — | — | — | — |
| Pallacanestro Interclub | — | — | — | — |
| Pallacanestro Livorno | — | Livorno | — | — |
| Pallacanestro Lucca | — | Lucca | — | — |
| Pallacanestro Mantovana | — | Mantua | 2004 | — |
| Pallacanestro Marsala | — | — | — | — |
| Pallacanestro Messina | — | Messina | 1976 | — |
| Pallacanestro Olimpia La Spezia | — | La Spezia | 1969 | — |
| Pallacanestro Pavia | — | Pavia | 1943 | — |
| Pallacanestro Petrarca Padova | — | Padua | 1934 | — |
| Pallacanestro Reggiana | Serie A | Reggio Emilia | 1974 | PalaBigi |
| Pallacanestro Ribera | — | — | 1969 | — |
| Pallacanestro Ruvo di Puglia | — | — | — | — |
| Pallacanestro Sanga Milano | — | Milan | — | — |
| Pallacanestro Treviso | Serie A | Treviso | 1954 | Palaverde |
| Pallacanestro Vicenza | — | Vicenza | — | — |
| Pallacanestro Virtus Cassino | — | Frosinone | 2011 | — |
| Pallalcesto Amatori Udine | inactive | Udine | 1944 | Palasport Primo Carnera |
| Palmares Catania | — | Catania | — | — |
| Partenope Napoli | — | Sant'Antimo | 1957 | — |
| PCR Messina | — | Messina | — | — |
| Perugia Basket | — | — | — | — |
| Pescara Basket | Serie C (Italian men's basketball league) | Pescara | — | PalaElettra |
| PF Schio | — | Schio | 1973 | — |
| Philadelphia 76ers | National Basketball Association | Philadelphia | 1946 | Xfinity Mobile Arena, Toyota Coliseum, Philadelphia Arena, Spectrum, Philadelphia Convention Hall and Civic Center, Oncenter War Memorial Arena |
| Phoenix Suns | National Basketball Association | Phoenix | 1968 | Arizona Veterans Memorial Coliseum, Mortgage Matchup Center |
| PMS Basketball | — | Moncalieri | — | — |
| PMS Torino | Serie A | Turin | 2009 | — |
| Poderosa Pallacanestro Montegranaro | — | Montegranaro | 1993 | — |
| Polisportiva Cervia Milano Marittima | — | — | — | — |
| Polisportiva Dinamo | Serie A | Sassari | 1960 | Palasport Roberta Serradimigni |
| Polisportiva Dinamo | — | — | — | — |
| Polisportiva Dinamo Lab | — | — | — | — |
| Polisportiva Folgore Nocera | — | — | — | — |