| cudeso.be | West Flanders |
| CuraVac Europe S.A. | |
| CuReMa B.V.B.A. | Antwerp |
| Customs4trade | |
| Cvjetic Développements et Études informatique | Liège |
| CVWarehouse | Antwerp |
| Cyanne | Liège |
| Cyber Technology B.V.B.A./S.P.R.L. | Brussels-Capital |
| Cybernet S.A. | Liège |
| Cybernoia B.V. | Antwerp |
| Cybersec Europe | Brussels-Capital |
| CYTAL Business Systems B.V.B.A. | Antwerp |
| D Soft N.V. | East Flanders |
| D&O Partners | Brussels-Capital |
| D.Products S.A./N.V. | Walloon Brabant |
| Dago | Antwerp |
| Damnet | |
| Data Science at Home | |
| Data-Concept | Walloon Brabant |
| Data-M N.V. | East Flanders |
| Data.gov.be | Brussels-Capital |
| Datacore B.V. | |
| Datadobi | |
| Dataline Solutions N.V. | West Flanders |
| Datamotive | |
| Datamundi | |
| Dataplan | |
| DataRescue S.A./N.V. | Liège |
| Datart | Antwerp |
| DataScouts | |
| DataScouts | East Flanders |
| DataStation | Antwerp |
| DataStories International N.V. | |
| Datavillage | |
| Datelist | |
| DCP SoftWare | West Flanders |
| DCstar N.V. | West Flanders |
| DDC International S.A. | Walloon Brabant |
| De Cronos Groep | Antwerp |
| de Duve Institute | |
| De Winkelhaak | |
| Defence Innovation Accelerator for the North Atlantic | |
| Defiants | |
| Defimedia | Namur |
| Defisat | Flemish Brabant |
| Delen Private Bank | |
| Deliverect | |
| Delta Investment Tracker | |
| Delta Software Services B.V.B.A. | Flemish Brabant |
| Delta Solutions | West Flanders |