| Coastal Trading & Engineering Company W.L.L | Construction |
| Cofely Besix Mannai Facility Management LLC | Real Estate |
| Collaborative Endeavour Contracting Co WLL | Conglomerates |
| College of the North Atlantic - Qatar | Education |
| Colors & More | Media |
| Commercial Bank Financial Services (L.L.C.) | Financial Services |
| Commitement Engineering Works | Construction |
| COMMITMENT ENGG. WORKS | Construction |
| Commodore Qatar Contracting Company L.L.C. | Construction |
| Communications Regulatory Authority | Governmental Institutions |
| Computer Arabia W.L.L. | Information Technology |
| Computer World | Conglomerates |
| Concorde Hotel Doha | Leisure and Tourism |
| Confidence Engineering and Development Company | Construction |
| ConocoPhillips Qatar Ltd | Oil and Gas |
| Conserved Foodstuffs Distribution Company W.L.L. | Food and Beverages |
| Consolidated Gulf Company | Information Technology |
| Construction Commissioning Maintenance Services WLL | Construction |
| Construction Dynamics LLC | Construction |
| Consulting Engineering Group | Construction |
| Container Freight Station | Conglomerates |
| Contraco WLL | Construction |
| Contrade Company Trading and Contracting | Construction |
| Control Contracting & Trading Co. (Pvt.) Qatar | Conglomerates |
| Contromet W.L.L | Construction |
