| O'Clock Brewing / Bakunin | |
| O'Connor Brewing Company | Norfolk, VA |
| O'Dempsey's | Atlanta |
| O'Fallon Brewery | O'Fallon, Missouri |
| O'Gara's Bar & Grill | Saint Paul, Minnesota |
| O'Grady's Brewery and Pub #1 | Arlington Heights, Illinois |
| O'Hanlon's Brewing Company Ltd. | Exeter, United Kingdom |
| O'Hara's Brewery | Ireland |
| O'Hara's Brewpub and Restaurant | Saint Cloud, Minnesota |
| O'so Brewing Company | |
| O.T. Brewing Company | Calgary, Canada |
| O/O / Stigbergets Bryggeri | Sweden |
| O/O Brewing | Göteborg, Sweden |
| Oak Creek Brewery | Sedona, Arizona |
| Oak Highlands Brewery | Dallas, TX |