| Cybermalveillance.gouv.fr | Paris |
| Cybernétix | Bouches-du-Rhône |
| Cybernettic | Creuse |
| Cyberprotect | Métropole de Lyon |
| Cyberté Création S.A.R.L. | Drôme |
| CyberVadis S.A.S. | |
| Cyberwatch | |
| Cyceo Informatique | Hauts-de-Seine |
| Cyceron | |
| Cycle | |
| Cyllene S.A.S. | Paris |
| Cymax Studios | Tarn-et-Garonne |
| Cyres | Paris |
| Cyril Vincent Conseil | Isère |
| CYTOO S.A. | |
| CYWYC | |
| D&A Pharma | |
| D-AIM | Hauts-de-Seine |
| D-EDGE | Paris |
| D-Fuzion | Gironde |
| D-GRAPH | Bas-Rhin |
| D-ICE Engineering | |
| D-impulse | |
| d-story | |
| D2B Consulting | |
| D3COM | |
| D3E Électronique S.A.S. | Aube |
| D@M Prod | Nord |
| Dactem | Gard |
| Dagoma | Nord |
| Dahu | Savoie |
| Dailymotion | Paris |
| Daitem | Bas-Rhin |
| Daiteo | |
| Dalibo | |
| Dalt | |
| Daltoner | Manche |
| Damaris | Métropole de Lyon |
| Damien Goubeau Développement | Haute-Garonne |
| DANEM | Val-de-Marne |
| Daniel Duverney | |
| Danka | |
| Danphil Conseils | Hauts-de-Seine |
| Dapfor S.A.R.L. | Hauts-de-Seine |
| Dareboost | |
| DareWin | |
| DARK | |
| Darktrace | Paris |
| Darsite S.A.R.L. | Paris |
| Dassault Aviation | |