| Oaken Barrel Brewing | Greenwood, Indiana |
| Oakham Ales | Peterborough, United Kingdom |
| Oakland Brewing Company | |
| Oakshire Brewing | Eugene, Oregon |
| Oasis Brewery and Restaurant | Boulder, Colorado |
| Oasis Brewery Annex | Boulder, Colorado |
| Oasis Texas Brewing Company | Austin |
| Oast House Brewers | Niagara-on-the-Lake, Canada |
| Obec Brewing | Seattle, Washington |
| Obercreek Brewing Company | Wappingers Falls |
| Obolon Brewery | Kiev, Ukraine |
| Ocean City Brewing Company | Ocean City |
| Oceanbryggeriet | Göteborg, Sweden |
| Oceanside Ale Works | Oceanside, California |
| Ocelot Brewing | Dulles, VA |