- Louis Obert Brewing Co.
- Oconto Brewing Co.
- John F. Oertel
- The Oertel Co., Inc.
- Oertel Brewing Co.
- P. M. Ohmeis & Co.
- Old Dominion Brewing & Ice Co.
- Old Dutch Brewers, Inc.
- Old England Brewing Co., Inc.
- Old Reading Brewery, Inc.
- Oldenburg Brewery & Entertainment Center
- Olean Brewing Co.
- The Olt Bros. Brewing Co.
- Olympia Brewing Co.
- Olympia Brewing Co.
- Olympia Bottling Co.
- Omaha Brewing Association
- Brewery Ommegang
- Oneida Brewing Co.
- Orange Brewery
- Orange County Brewery, Inc.
- Oriskany Falls Brewing Co.
- Henry F. Ortlieb
- Henry F. Ortlieb Brewing Co.
- Ortlieb Brewing Co. - Mauch Chunk
- Ortonville Bottling Co.
- Henry J. Oserstock, Seitz Brewery
- Oshkosh Brewing Co.
- V. A. Oswald, American Brewery
- Otto's Pub & Brewery
- Ouachaita Valley Bottle Works, Ltd.
O
