| C.F. Møller Architects | 8000 | Aarhus C |
| C.K. Produktion | 7190 | Billund |
| C2Elements ApS | 5250 | Odense SV |
| Cadskolen A/S | 9000 | Aalborg |
| Carl Ras A/S | 2730 | Herlev |
| Carl Stahl A/S | 7000 | Fredericia |
| Carlo Gavazzi Handel A/S | 8370 | Hadsten |
| Carlog System | 9440 | Aabybro |
| CB Group | 5000 | Odense C |
| CB Svendsen A/S | 3500 | Værløse |
| Ceetec A/S | 5500 | Middelfart |
| Celero Danmark A/S | 3540 | Lynge |
| Celsa Steel Service A/S | 3650 | Ølstykke |
| Centrum Pæle A/S | 7100 | Vejle |
| CEPELO A/S | 9200 | Aalborg SV |
| CERTEX Danmark A/S | 6500 | Vojens |
| CESCO A/S | 6690 | Gørding |
| Cetonia A/S | 8850 | Bjerringbro |
| Charles Christensen A/S | 2730 | Herlev |
| City Group Brandsikring A/S | 5500 | Middelfart |
| City Group Overfladebehandling A/S | 5500 | Middelfart |
| CJ A/S | 7000 | Fredericia |
| Colas Danmark A/S | 2600 | Glostrup |
| Colloc ApS | 8381 | Tilst |
| Combitherm A/S | 8653 | Them |
| ComSystem A/S | 3490 | Kvistgård |
| Condair A/S | 8680 | Ry |
| CONFAC A/S | 8940 | Randers SV |
| Conmas ApS | 9800 | Hjørring |
| Constructor Danmark A/S | 4320 | Lejre |
| Copenhagen Hardwood ApS | 3670 | Veksø Sjælland |
| Coromatic A/S | 4000 | Roskilde |
| CP ApS | 4130 | Viby Sjælland |
| Cre8tek Denmark ApS | 9800 | Hjørring |
| CRECEA A/S | 8000 | Aarhus C |
| CRH Concrete A/S | 4130 | Viby Sjælland |
| CSK Stålindustri A/S | 7700 | Thisted |