| Comstrat | Brussels-Capital |
| Concar N.V. | Antwerp |
| Confo Therapeutics | |
| Connect Group N.V. | Flemish Brabant |
| Connect Pro | East Flanders |
| Connective | Antwerp |
| Connects | |
| Connexeon.com B.V.B.A. | Antwerp |
| ConsulTIC S.R.L. | |
| ContactOffice | Brussels-Capital |
| Contentment | |
| Contractify | |
| Contraste Europe | Brussels-Capital |
| Contribute N.V. | Antwerp |
| Control & Protection Automation N.V. | Antwerp |
| Convert Pharmaceuticals S.A. | |
| convEyXO | |
| Coop IT Easy | |
| Corelan Cybersecurity Research | |
| Corilus N.V. | |
| Coris Bioconcept | |
| CorpaTech | Limburg |
| Coteng N.V. | Antwerp |
| Cotrain | Antwerp |
| Cotubex S.A. | Brussels-Capital |
| Council of European Professional Informatics Societies | Brussels-Capital |
| Cownected | |
| Craftworkz | |
| Crazy Monkey Studios | Antwerp |
| CrazyGames | |
| Creaceed S.P.R.L. | Hainaut |
| Création site web | Hainaut |
| Creations.be | West Flanders |
| Creativeroom | |
| CREAX N.V. | West Flanders |
| Credix | |
| Crelan | |
| CRM Group | West Flanders |
| Cronit | |
| Cronos | |
| Crunch Analytics | |
| CryoTherapeutics S.A. | |
| CryptoNet B.V.B.A. | Flemish Brabant |
| CSi Tools | Flemish Brabant |
| Cuarta | East Flanders |
| Cubigo N.V. | Limburg |
| Cucumber Apps | |
| cudeso.be | West Flanders |
| CuraVac Europe S.A. | |
| CuReMa B.V.B.A. | Antwerp |