| Onsted Community Schools, MI (District) |
| Ontario County, NY (ISD) |
| Ontario Local School District, OH (District) |
| Ontario Sd 8C, OR (District) |
| Ontario-Montclair, CA (District) |
| 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) |
