| O.T.S. Cleaning Co. W.L.L | Services |
| Oasis Cars | Transport |
| Oasis Elevators Company WLL | Services |
| Obaikan Equipment & Services W.L.L | Industrial Manufacturing |
| OCS Qatar LLC | Real Estate |
| Octogone Qatar WLL | Industrial Manufacturing |
| Off Road WLL | Services |
| Oilfield Projects Dev Co Wll ( Opd Group) Qatar | Conglomerates |
| OITC Group W.L.L | Construction |
| OITC Travel & Toursim | Leisure and Tourism |
| Olympic Sports Company W.L.L | Retail |
| Omega Engineering W.L.L | Construction |
| Omni Collection | Industrial Manufacturing |
| Oneteam Clothing Company | Retail |
| Oola Sports LLC | Retail |
| OOREDOO Q.S.C. | Telecommunications |
| Opticsense | Telecommunications |
| Optimum Systems W.L.L. | Information Technology |
| Orbit Trading & Contracting Co. | Construction |
| Oriental Trading Company Limited | Industrial Manufacturing |
| Oryx Advertising Company WLL | Media |
| Oryx Alliance | Construction |
| Oryx Energy Projects & Services LLC | Services |
| Oryx Engineering Solutions LLC | Construction |
| ORYX GTL Ltd. | Oil and Gas |