| Cove Recruitment Ltd | Administrative & support | 2017 |
| COX Investment Group Ltd | Real estate | 2021 |
| CPO Plant Hire Ltd | Administrative & support | 2022 |
| Craig Hinks Limited | Wholesale & retail | 2007 |
| Cranmore Cole Ltd | Wholesale & retail | 2025 |
| Craxford Brothers (USK) Limited | Construction | 2011 |
| Creative Difference Training Ltd | Professional & scientific | 2012 |
| Creative Expression Made Easy Ltd | Education | 2022 |
| Crispin Barker Ltd | Wholesale & retail | 2025 |
| CRL Projects Limited | Wholesale & retail | 2018 |
| Cropthorne Eden Ltd | Wholesale & retail | 2025 |
| Crosscue Ltd | Information & communication | 2014 |
| Crossfield Elmore Ltd | Wholesale & retail | 2025 |
| Crossfit Shadow Valley Ltd | Arts & recreation | 2015 |
| Crow Valley Accountancy Ltd | Professional & scientific | 2014 |
| Csiaal Trans Ltd | Transport & logistics | 2020 |
| CT Heritage Estates Ltd | Construction | 2026 |
| CT04 Promotions Limited | Arts & recreation | 2022 |
| CT45 Properties Limited | Real estate | 2025 |
| Ctrl 4 Ltd | Hospitality | 2019 |
| Cunard White Ltd | Wholesale & retail | 2025 |
| Custom Controls Limited | Professional & scientific | 2003 |
| Custom Spray Ltd | Extraterritorial | 2023 |
| Cwmbran Acupuncture Ltd | Other services | 2015 |
| Cwmbran Property Developments Ltd | Construction | 2020 |
| Cwmbran Tyres & Repairs Ltd | Wholesale & retail | 2026 |
| Cwmffrwd Service Station Co.Limited | Wholesale & retail | 1964 |
| Cwrt Tredomen Management Limited | Households | 2003 |
| Cwtch Accommodation Limited | Real estate | 2026 |
| Cyfannol Women's AID Ltd | Health & social care | 1994 |
| Cyionics Limited | Professional & scientific | 1999 |
| CYM SOL Ltd | Construction | 2018 |
| D Bendon Construction Limited | Construction | 2010 |
| D C Electrical Maintenance Limited | Manufacturing | 2003 |
| D George Limited | Construction | 2014 |
| D George Property Limited | Real estate | 2016 |
| D Walker Roofing Specialist Ltd | Construction | 2017 |
| D. Lucas & Sons Limited | Construction | 1994 |
| D.J.J. Precision Engineering Limited | Manufacturing | 1983 |
| D.K.P. Engineering Services Limited | Manufacturing | 2001 |
| D3 Property Developments Limited | Construction | 2014 |
| D3 Roofing Limited | Construction | 2019 |
| Dale Young Ltd | Other services | 2009 |
| DAN Foley Ltd | Real estate | 2020 |
| Dark Sheep Studio Ltd | Other services | 2023 |
| Darkside Tanning Studio Limited | Administrative & support | 2017 |
| Darren Mobile Tyres Ltd | Manufacturing | 2024 |
| Dave's Body Shop Limited | Wholesale & retail | 2002 |
| David Smith Holdings Ltd | Financial services | 2025 |
| David Turner Construction Ltd | Construction | 2020 |
| Dawn to Dusk Commercials Limited | Wholesale & retail | 2016 |
| Dekan Barber Limited | Other services | 2016 |
| Delahay Print & Sign Limited | Manufacturing | 2006 |
| Delamere Trading Limited | Real estate | 2020 |
| Deli Homes Limited | Real estate | 2025 |
| Demand LED Ltd | Extraterritorial | 2004 |
| Denmark Capps Ltd | Wholesale & retail | 2025 |
| Denmore Homes Limited | Construction | 2016 |
| Denton Clays Ltd | Wholesale & retail | 2025 |
| Denville Mead Ltd | Wholesale & retail | 2025 |
| DEP Avon Limited | Hospitality | 2025 |
| Desh Ltd | Hospitality | 2026 |
| Design Futures Limited | Other services | 2003 |
| Designbuilduk Ltd | Construction | 2024 |
| DEW Mechanical Limited | Construction | 2024 |
| Dialogue Consulting Ltd | Education | 2004 |
| Diamondpak Limited | Manufacturing | 2007 |
| Dibden North Ltd | Wholesale & retail | 2025 |
| Didcot Strafton Ltd | Wholesale & retail | 2025 |
| Dilys & Dotti Ltd | Wholesale & retail | 2025 |
| Dios Cuts Ltd | Other services | 2022 |
| Dirty Pawz Ltd | Other services | 2022 |
| Diversity Day Care Ltd | Education | 2025 |
| DJ Ball Civil Engineering Limited | Construction | 2015 |
| DJH Property Maintenance Group Ltd | Households | 2023 |
| DJS Electrical Ltd | Construction | 2015 |
| DM & Co Electrics Ltd | Construction | 2023 |
| Domjorella Developments Limited | Construction | 2018 |
| Donovan's Auto Services Limited | Wholesale & retail | 2016 |
| Down to Earth (Wales) Services Ltd | Administrative & support | 2023 |
| DR Bachs AG LLP | | 2023 |
| Dragon Direct Limited | Wholesale & retail | 2017 |
| Dragon Hire Services Ltd | Administrative & support | 2026 |
| Dragon Plant Sales Ltd | Manufacturing | 2025 |
| Dragon Property Services Ltd | Construction | 2018 |
| Dragonblinds Wales Ltd | Manufacturing | 2023 |
| Draw a Blank Ltd | Manufacturing | 2021 |
| Drews Brews Limited | Hospitality | 2026 |
| DRIVE44 Ltd | Manufacturing | 2023 |
| Driven Motors Ltd | Wholesale & retail | 2025 |
| Drumcliffe House Ltd | Wholesale & retail | 2024 |
| DRY INK Limited | Professional & scientific | 2019 |
| DT Landscapes & Tree Services Ltd | Administrative & support | 2026 |
| DTG Consultancy Services Ltd | Information & communication | 2019 |
| Dublin South Ltd | Wholesale & retail | 2024 |
| Duffryn Estate Limited | Construction | 2013 |
| Dunkeld Rannoch Ltd | Wholesale & retail | 2025 |
| Dunmail Lanes Ltd | Wholesale & retail | 2025 |
| Dunnrite Ltd | Construction | 2018 |
| Dunwood Austin Ltd | Wholesale & retail | 2025 |