| Craigs Car Care | Car manufacturer | Unit 5 Lamby Way Workshops | Mon–Fri 08:00–17:00 |
| Crate Hire Express | Packaging supply shop | Unit 2 Waterside Business Park | Mon–Fri 08:30–17:30 |
| Creo | Internet marketing service | The Old Church, 76 Wells St | Mon 09:00–17:00 |
| Crown Damp Proofing Company | Waterproofing service | 23a Allerton St | Mon–Sat 09:00–18:00 |
| Crownford | Employment consultant | Cardiff Business Park, Suite 107, Regus, Cardiff Rd | Mon–Fri 09:00–17:00 |
| Crumbs Kitchen | Vegetarian restaurant | 33 Morgan Arcade | Mon–Sat 09:00–16:00 |
| Curry Hut Cardiff | Sri lankan restaurant | 96 Salisbury Rd | Daily 17:00–23:00 |
| Cyncoed Medical Centre | Doctor | Dartington Dr | Mon–Fri 08:00–18:00 |
| D J Evans Forse & Co Funeral Directors | Funeral director | Whitchurch Funeral Home, Whitchurch Common | Daily Open 24 hours |
| D&G Office Interiors Ltd. - Workplace Design & Office Furniture Experts | Office furniture shop | Design House, Lamby Industrial Park, Wentloog Ave | Mon–Fri 08:00–17:30 |
| D2zign Exhibitions and Interiors Ltd | Exhibition planner | 4 Panteg | Mon–Tue 09:00–17:00 |
| Dalchini | Breakfast | Indian Restaurant | Breakfast restaurant | 10 MacKintosh Pl | Mon 09:30–14:00, 17:00–23:00 |
| DAX Studio | Web designer | Unit 4, Boomerang Parc | Mon–Sat 08:00–18:00 |
| DCBL Direct Collection Bailiffs Limited | Debt collection agency | Sophia House, 28 Cathedral Rd | Mon–Thu 09:00–17:00 |
| DD Glass Balustrades (Cardiff) | Railing contractor | Sophia House, 28 Cathedral Rd | Daily Open 24 hours |
| Deccan Express | Variety shop | 123 Richards St | Mon–Thu 10:00–18:00 |
| DecoHeat | Tienda de chimeneas | Merthyr Rd | Mon–Fri 09:00–17:00 |
| Deja Vu Wales | Second-hand clothing shop | 1, 200 Pontcanna St, Kings Rd | Sat–Sun 10:00–16:00 |
| Demiro's | Welsh restaurant | Unit 26, Mermaid Quay | Mon 12:00–23:00 |
| Dewis Financial Planning | Financial planner | 11-13 Penhill Rd | Mon–Fri 08:00–18:00 |
| Digi4u | Mobile phone accessory shop | Waterside Business Park, Lamby Way | Mon–Fri 09:00–17:30 |
| Dipec Plastics Holdings Ltd | Plastic fabrication company | Cambria House, 156 North Rd | Mon–Fri 08:00–17:00 |
| Direct Source (U.K.) Ltd | Tienda de trofeos | 2B, Gwaelod Y Garth Industrial Estate | Mon–Fri 09:00–17:00 |
| Direct Storage | Self storage facility | Ste 5, 6-7 Bessemer Cl | Mon 09:00–17:00 |
| Do You Believe? Bridal & Prom Boutique | Wedding shop | 91 Caerphilly Rd | Wed 10:00–17:30 |
| Don Skene Cycles | Bicycle shop | 769 Newport Rd | Mon–Fri 09:00–18:00 |
| DoorMate | Door supplier | Rear of, 216 Newport Rd | Mon 09:00–17:30 |
| Doran Tactical Innovations | Fabric product manufacturer | Unit 6, Fairwater Workshops, Norbury Rd | Wed Open 24 hours |
| Doyle Davies - Insolvency Practitioners Cardiff | Estate liquidator | 6, Ynys Bridge Court | Mon–Thu 09:00–17:00 |
| DRAC Consulting Ltd | Engineering consultant | 4 Ty-Nant Ct | Thu 08:30–17:00 |