| Oakes | E. M. Oakes & Company |
| Oakes | Edward Oakes & Son |
| Oakes | Hawksworth, Oakes & Company |
| Oakes | Oakes, Tompkin & Ward |
| Oakes | Shemeld & Oakes |
| Oakes | William & John Oakes |
| Oates | Albert Oates |
| Oates | Francis Oates |
| Oates | George Oates |
| Oates | Isaac Oates & Son |
| Oates | Luke Oates & Company |
| Oates | Oates, Colley & Wigham / Oates & Colley |
| Oates | Robinson & Oates |
| Oates | William Oates |
| Oates | William Oates & Company |
| Oborne | Oborne & Gunning |
| Ogden | Bingham & Ogden |
| Ogden | Ogden Brothers & Derby |
| Old | Old Hall |
| Oldfield | C. Oldfield |
| Oldham | J. H. Oldham |
| Oldham | James Oldham & Company |
| Oliver | J. Oliver & Sons |
| Oliver | Oliver & Bower Ltd |
| Oliver | Oliver & Ogle |
| Oliver | Oliver and Webster |
| Oliver | William Oliver |
| Oneida | British Oneida Community Ltd |
| Osbaldiston | Louis Osbaldiston & Company |
| Osborn | Charles Osborn |
| Osborn | Clark & Hall / Clark & Osborn |
| Osborn | Osborn & Sons |
| Osborne | Alfred Osborne |
| Osborne | Edward Osborne |
| Osborne | Osborne & Company (Sheffield) Ltd |
| Osborne | Osborne Tableware Ltd |
| Osborne | Percy Osborne & Son Ltd |
| Osborne | Thomas E. Osborne & Company Ltd |
| Osborne | Thomas Osborne / Benjamin Osborne |
| Otley | Thomas Otley & Sons Ltd |
| Oughtibridge | Oughtibridge Equitable Co-operative & Industrial Society Ltd |
| Ovicto | Ovicto |
| Owen | Charles Owen & Company / Owen Brothers |
| Owen | Latham & Owen Ltd |
| Owen | Owen & Webster |
| Owen | Robert Owen |
| Owen | Robert Owen / Denison Owen |
| Oxley | Atkin, Oxley & Co |
| Oxley | James Oxley (Sheffield) Ltd |
| Oxley | John Oxley & Company |
| Oxley | Law, Atkin & Oxley |
| Oxley | Thos Oxley Ltd |
| Oxspring | George Oxspring |
