| DMW Consultancy Ltd | Kent |
| DMWF Ltd | Bristol |
| DNA IT Solutions | |
| DNA Worldwide Group Ltd | |
| DNAe Group Holdings Ltd | |
| DName-iT Holdings Ltd | |
| DnaNudge | |
| DNASTREAM | Surrey |
| DNC Software Ltd | Lincolnshire |
| DNEG | |
| DNW Solutions Ltd | |
| Do London Ltd | |
| Doccla | |
| DocketManager | |
| DOCOSoft | |
| Docstack Ltd | |
| docStribute | |
| Doctify Ltd | |
| Doctorpreneurs Ltd | |
| Doctrin Ltd | |
| Documation | Hampshire |
| Document Direct | |
| Document Logic | North Yorkshire |
| Document Logistix Ltd | |
| Document Management Technology Ltd | |
| Document Options Ltd | West Sussex |
| Document Scanning Solutions Ltd | Greater London |
| Document Technologies Ltd | Northamptonshire |
| Docusoft Ltd | |
| Doddle Agency | |
| Dodl Digital | |
| Dodo Software Ltd | |
| Doepud Web Design | Highland |
| Dofollow Ltd | |
| DoganTech Ltd | |
| Doherty Associates | Greater London |
| Dojo Learning | |
| Dokkit | |
| Dold Industries Ltd | Essex |
| Dolomite Bio | |
| Dolphin Computer Access Ltd | Worcestershire |
| Dolphin Computer Upgrades Ltd | East Sussex |
| Dolphin I.T. | Essex |
| Dolphin IT Solutions | |
| Dolphin Promotions | Lancashire |
| Domain Design Agency Ltd | Glasgow |
| Domain For Sale | |
| Domain Name Brokers | |
| Domain Recover | Bedfordshire |
| Domaincheck | County Durham |