| Ontech Charter High School, NY (PSA) |
| Onteora Central School District, NY (District) |
| Ontonagon Area Schools, MI (District) |
| Oologah-Talala, OK (District) |
| Oostburg School District, WI (District) |
| Opdyke-Belle-Rive CCSD 5, IL (District) |
| Opelika City, AL (District) |
| Open Classroom, UT (PSA) |
| Open High School Of Utah, UT (PSA) |
| Opheim K-12 Schools, MT (District) |
| Opp City, AL (District) |
| Oppenheim Ephratah, NY (DISTRICT) |
| Oppenheim-ephratah-st. Johnsville Csd, NY (District) |
| Opportunity Charter School, NY (PSA) |
| Optima, OK (District) |
