| Oracle Corporation |
| Oracle Corporation UK Limited |
| Orange Organisation |
| Orange Tunisie SA |
| Orascom Construction Plc |
| Orascom Group |
| Org Beverages SARL |
| Organic Seed & Bean Co Ltd |
| Organisation for the Professional Empowerment of Women |
| Orient Productions |
| Orkla ASA |
| Ornua Co-operative Limited |
| Oromia Insurance S.C. |
| Orveon |
| Out of the Box |
| Outdoor & Sports Company (OSC) Limited |
| Outsider |
| OVO Group Ltd |
| Oxfam Activities Limited (OAL) |
| Oxfam GB |
| Oxford EMI |
| Oxford Policy Management |
| Oyla (Popular Science) |
| P2 Energy Solutions |
| Pablo Media |