| C.K. Environment A/S | 3500 | Værløse |
| C2Elements ApS | 5250 | Odense SV |
| Cabicon A/S | 5220 | Odense SØ |
| CAD Kompagniet A/S | 2730 | Herlev |
| Cadskolen A/S | 9000 | Aalborg |
| CADXpert a/s | 8700 | Horsens |
| Carl Stahl A/S | 7000 | Fredericia |
| Carlo Gavazzi Handel A/S | 8370 | Hadsten |
| CASA A/S | 8700 | Horsens |
| CB Svendsen A/S | 3500 | Værløse |
| CBI Danmark A/S | 7480 | Vildbjerg |
| Ceetec A/S | 5580 | Nørre Aaby |
| Celsa Steel Service A/S | 3650 | Ølstykke |
| Cembrit A/S | 9100 | Aalborg |
| Center for Underleverandører | 7400 | Herning |
| Centrum Pæle A/S | 7100 | Vejle |
| Certego A/S | 2730 | Herlev |
| CERTEX Danmark A/S | 6500 | Vojens |
| CESCO A/S | 6705 | Esbjerg Ø |
| CG Jensen A/S | 2600 | Glostrup |
| Charles Christensen A/S | 2730 | Herlev |
| CHISA A/S | 2770 | Kastrup |
| CJ A/S | 7000 | Fredericia |
| CJ Truckservice ApS | 5500 | Middelfart |
| Clemco Danmark A/S | 8660 | Skanderborg |
| CN3 A/S | 2800 | Kgs. Lyngby |
| Colas Danmark A/S | 2600 | Glostrup |
| College360 | 8600 | Silkeborg |
| Colloc A/S | 8381 | Tilst |
| Colour Compagniet A/S | 6933 | Kibæk |
| Comadan A/S | 8940 | Randers SV |
| COMBITHERM A/S | 8653 | Them |
| Complement A/S | 7100 | Vejle |
| Condair A/S | 8680 | Ry |
| CONFAC A/S | 8940 | Randers SV |
| Contec Prefab A/S | 8270 | Højbjerg |
| Contiga Tinglev A/S | 6360 | Tinglev |
| Cool Ceiling A/S | 2600 | Glostrup |
| Copenhagen Hardwood ApS | 3670 | Veksø Sjælland |
| Coromatic A/S | 5220 | Odense SØ |
| CP ApS | 4130 | Viby Sjælland |
| Cp Sourcing ApS | 7870 | Roslev |
| Craneteam ApS | 8670 | Låsby |
| Cre8tek Denmark ApS | 9800 | Hjørring |
| CRH Concrete A/S | 4130 | Viby Sjælland |
| Curacon A/S | 2730 | Herlev |
