| Brewery | Location |
|---|---|
| OEC Brewing (Ordinem Ecentrici Coctores) | Oxfort, CT |
| Oedipus Brewing | Amsterdam, Netherlands |
| Oersoep | |
| Off Color Brewing | Chicago |
| Off Color/Amager Bryghus | |
| Oggi's Pizza and Brewing - Vista | Vista, California |
| Ohio Brewing | Niles, Ohio |
| Okanagan Spring Brewery | Vernon, Canada |
| Old Chimney's Brewery | United Kingdom |
| Old City Brewing | Austin, Texas |
| Old Dominion Brewing Co. | Dover, Delaware |
| Old Hat Brewery | Lawton, Michigan |
| Old Orange Brewing Co. | Orange, Ca. |
| Old Redwood Brewing Co. | Windsor, California |
| Old Schoolhouse Brewery | Winthrop, WA |