| C&A | C&M | C.F. Müller Campus |
| Cafe | Call Center | Call Shop |
| Calumet Photographic | Camaflex | Camping |
| Campingausrüstung | Campingbedarf | Camping Club |
| Campinghandel | Campingladen | Campingplatz |
| Campingzubehör | CAMPUS72 | Capgemini |
| Caravan | Carglass | Caritas |
| Caritasverband | caritative Organisationen | Carl Duisberg Deutschkurse |
| Carport | Casino | Casio |
| Catering | Cateringservice | CBRE |
| CD-Produzenten | CDM Smith | CDU |
| CECIL | Cellent Consulting | Chemie |
| Chemiehandel | Chemikalien | chemische Industrie |
| chemische Reinigung | China Imbiss | China Restaurant |
| Chinarestaurant | Chinese | chinesisches Restaurant |
| Chinesisch Essen | Chiropraktik | Chiropraktiker |
| Chirotherapie | Chirurg | Chirurgie |
| Chor | Chorgemeinschaft | christliche Vereinigung |
| Christ Rechtsanwälte | Cinebank | Cinegate |
| Cinemaxx | Citizen | City Parfümerie |
| CJD | Cleanskin | Clinique |
| Clown | Clubhaus | Clubs |
| CMS Hasche Sigle | CNC | Coaching |
| Cocktailbar | Cocktails | Cocktailservice |
| Cofely Refrigeration | Coffee-Shops | Coiffeur |
| Colloseum Mode | Colt Technology Services | Comet Computer |
| Comiczeichner | comma | Commerzbank |
| Computer | Computergrafik | Computer Großhandel |
| Computerkurse | Computerladen | Computerreparatur |
| Computertechnik | Computertomographie | Computer Versandhandel |
| Computerzubehör Großhandel | Computerzubehör Hersteller | Concordia Versicherung |
| Condensator Dominit | Confiserie | Conrad |
| Consilia Wirtschaftsprüfung | Consulting | Container |
| Containerdienst | Containerservice | Containertransporte |
| Continentale | Copyshop | COP® Polizeiausrüstung |
| COREALCREDIT BANK | Cosmetic | Creditreform |
| CSC | CSU | Curacon Wirtschaftsprüfung |
| Cutting Crew | CVJM |
