| | Old Indiana Fun-n-Water Park | Thorntown, Indiana, United States | - | | - |
| | Olentangy Park | Columbus, Ohio, United States | - | | - |
| | Olimpyc Park | Santo Domingo Este, Santo Domingo, Dominican Republic | - | | - |
| Olivieri Luna Park | Oliveri, Sicily, Italy | - | ≤ | - |
| | Olympia Park | McKeesport, Pennsylvania, United States | - | | - |
| | Olympic Park | Irvington, New Jersey, United States | - | | - |
| | Olympic Park | Rochester, New York, United States | - | | - |
| Olympic Sports Park | Jiulongpo, Chongqing, China | SBNO | - | 1 |
| | Omaezaki Land | Omaezaki, Shizuoka, Japan | - | - | - |
| | Opryland USA | Nashville, Tennessee, United States | - | | - |
| | Orange County Fairgrounds | Middletown, New York, United States | Operating | - | - |
| | Oriental Park | Baiyun, Guangzhou, Guangdong, China | - | | - |
| | Oriental Science Fiction Valley | Nanming, Guiyang, Guizhou, China | - | | - |
| | Orient Culture Park | Xiaoshan, Hangzhou, Zhejiang, China | - | ≤ | - |
| | Orumieh Park | Urmia, West Azerbaijan, Iran | - | ≤ | - |
| | Ostdeutsche Austellung 1911 | Poznań, Wielkopolskie, Poland | - | | - |
| | Otaru Expo | Otaru, Shiribeshi, Hokkaido, Japan | - | | - |
| | Owasco Lake Park | Auburn, New York, United States | - | | - |
| | Oyama Yuenchi | Oyama, Tochigi, Japan | - | | - |
| | Pabst Park | Milwaukee, Wisconsin, United States | - | ≤ | - |
| | Pacific City | Burlingame, California, United States | - | | - |
| | Pacific Ocean Park | Santa Monica, California, United States | - | | - |
| | Palace and Casino Amusements | Asbury Park, New Jersey, United States | - | ≤ | - |
| | Palisades Amusement Park | Cliffside Park, New Jersey, United States | - | | - |