| Venue | Location | Capacity | Opened | Sport |
|---|---|---|---|---|
| Oakland Arena | Oakland | 19,596 seats | November 9, 1966 | — |
| Oakland Ballpark | San Jose, Oakland | 32,000 seats | — | baseball |
| Odde Ice Center | — | 1,600 seats | 1980 | — |
| Ohio Stadium | Columbus | 104,944 seats | October 7, 1922 | American football |
| Oklahoma State Fair Arena | Oklahoma City | 10,944 seats | 1965 | — |
| Omaha Civic Auditorium | Nebraska, Omaha, Douglas County | 10,960 seats | 1954 | — |
| Omni Coliseum | Atlanta | 16,181 seats | October 14, 1972 | basketball |
| Oncenter War Memorial Arena | Syracuse | 8,000 seats | September 12, 1951 | ice hockey, basketball |
| Oracle Park | San Francisco | 41,915 seats | April 11, 2000 | baseball |
| Oriole Park at Camden Yards | Baltimore | 48,876 seats | April 6, 1992 | baseball |
| OU Softball Complex | Norman | 1,378 seats | — | softball |