| Octopus Investments Ltd |
| Odgers Group Ltd. |
| Oetker Collection |
| Oikocredit Ecumenical Development Co-operative Society |
| Oji Holdings Corporation |
| OK PRODZHEKTS HO [OK Projects] |
| Okiocredit |
| Okta Inc. |
| Olaf & McAteer |
| Olam International Limited |
| Old Mutual Wealth |
| Olga |
| Olympique Mnihla |
| Omar Asghar Khan Development Foundation |
| Omidyar Network |
| Omnicom Group Inc |
| One Hotels & Resorts GmbH |
| One Village Limited |
| OneAdvent Limited |
| OneSavings Bank Plc |
| Onestream Limited |
| Only Natural Products Ltd |
| Open Social B.V. |
| Open Society Foundations (OSF) |
| Open University |