| Stadion | Lokasi | Kapasitas | Dibuka |
|---|---|---|---|
| Oakland Arena | Oakland | 19.596 kursi | 9 November 1966 |
| Oakland Ballpark | San Jose, Oakland | 32.000 kursi | — |
| Odde Ice Center | — | 1.600 kursi | 1980 |
| Oklahoma State Fair Arena | Kota Oklahoma | 10.944 kursi | 1965 |
| Omaha Civic Auditorium | Nebraska, Omaha, Douglas County | 10.960 kursi | 1954 |
| Oncenter War Memorial Arena | Syracuse | 8.000 kursi | 12 September 1951 |
| Oracle Park | San Francisco | 41.915 kursi | 11 April 2000 |
| Oriole Park at Camden Yards | Baltimore | 48.876 kursi | 6 April 1992 |
| OU Softball Complex | Norman | 1.378 kursi | 1998 |
| Oval Lingotto | Turin | 8.500 kursi | 2005 |