Select School Beginning with "O"
| School | League | County |
|---|---|---|
| Oak Harbor | Sandusky Bay Conference | Ottawa |
| Oak Hill | Southern Ohio Conference | Jackson |
| Oak Hills | Greater Miami Conference | Hamilton |
| Oakwood | Southwestern Buckeye League | Montgomery |
| Oberlin | Patriot Athletic Conference | Lorain |
| Old Fort | Midland Athletic League | Sandusky |
| Olentangy | Ohio Capital Conference | Delaware |
| Olentangy Liberty | Ohio Capital Conference | Delaware |
| Olentangy Orange | Ohio Capital Conference | Delaware |
| Olmsted Falls | Southwestern Conference | Cuyahoga |
| Olney Friends | Independents - Central, NW, SE | Belmont |
| Ontario | North Central Conference | Richland |
| Open Door Christian | Independents - Northeast Ohio | Lorain |
| Orange | Chagrin Valley Conference | Cuyahoga |
| Orrville | Ohio Cardinal Conference | Wayne |
| Otsego | Suburban Lakes League | Wood |
| Ottawa Hills | Toledo Area Athletic Conference | Lucas |
| Ottawa-Glandorf | Western Buckeye League | Putnam |
| Ottoville | Putnam County League | Putnam |
| Our Lady Of The Elms | Independents - Cleveland Catholic | Summit |
| Oyler | Cincinnati City SD | Hamilton |