| Custom Cat Creations Ltd | Manufacturing | 2026 |
| CUSTOMERBASE247 Limited | Wholesale & retail | 2020 |
| CV Water Consultancy Ltd | Professional & scientific | 2017 |
| Cwmheulog Limited | Agriculture & fishing | 2015 |
| Cwtch Alpacas Ltd | Agriculture & fishing | 2022 |
| Cwtch Angels Abergavenny Community Interest Company | Health & social care | 2020 |
| Cwtch Event Chaperone Ltd | Health & social care | 2024 |
| Cwtch Glamping Ltd | Hospitality | 2022 |
| Cyberspanner Limited | Information & communication | 2015 |
| D B C Dynamics Limited | Professional & scientific | 1996 |
| D J Kelly Cyfyngedig | Health & social care | 2023 |
| D-N-Advisory Limited | Professional & scientific | 2018 |
| Dagger Solutions Ltd | Public administration | 2017 |
| Dai's V-Dubs Limited | Wholesale & retail | 2025 |
| Dance Blast | Arts & recreation | 2002 |
| Datalytix Ltd | Information & communication | 2018 |
| Daveandersonart.Com Limited | Arts & recreation | 2011 |
| Davenport Fowler Limited | Real estate | 2018 |
| David Monkhouse Consulting Ltd | Professional & scientific | 2020 |
| Davies of Abergavenny Limited | Transport & logistics | 2012 |
| Davis & Sons Professional Services Limited | Real estate | 1996 |
| DAW Advisors Ltd | Professional & scientific | 2013 |
| Dazzle’Em Events Ltd | Professional & scientific | 2019 |
| DC Thomas & Sons Ltd | Construction | 2025 |
| DDC Web Ltd | Information & communication | 2025 |
| Deans Network & Security Ltd | Information & communication | 2024 |
| Decision Juice Ltd | Information & communication | 2012 |
| Delicious Pizza Limited | Hospitality | 2025 |
| Delyth Jones Consulting Limited | Administrative & support | 2003 |
| Derwendeg 1971 Limited | Extraterritorial | 2014 |
| Design Security Ltd | Professional & scientific | 2008 |
| Developa Limited | Professional & scientific | 2022 |
| Devon County Antiques Fairs Limited | Administrative & support | 2003 |
| Diggertraingandtesting Limited | Education | 2025 |
| Diggertraining Ltd | Education | 2018 |
| Display Sauce Limited | Wholesale & retail | 2009 |
| Divi Engine Limited | Professional & scientific | 2019 |
| DKH Project Services Ltd | Professional & scientific | 2026 |
| DL Corran Tree Surgeons Ltd | Agriculture & fishing | 2012 |
| DLJ Land Ltd | Real estate | 2020 |
| DNA Facilities Limited | Construction | 2015 |
| Dominic Irvine Ltd | Professional & scientific | 2012 |
| Domum Property Ltd | Real estate | 2022 |
| Dorrell Oliver Advisory Limited | Professional & scientific | 2024 |
| Dorrell Oliver Financial Services Limited | Financial services | 2001 |
| Dorrell Oliver Limited | Professional & scientific | 2005 |
| Dotv Safety Services Limited | Professional & scientific | 2017 |
| Douchecrest Limited | Households | 1982 |
| DR Arif Mahmood Ltd | Health & social care | 2012 |
| Dragon Dairies Ltd | Hospitality | 2025 |
| Dragon Decorative Coatings Ltd | Construction | 2022 |
| Dragon RS Europe Ltd | Water & waste | 2023 |
| Dragon RS Holdings Limited | Financial services | 2025 |
| Dragon's Breath Firewood Ltd | Agriculture & fishing | 2024 |
| Drat Property Limited | Real estate | 2024 |
| DRT Services Ltd | Wholesale & retail | 2026 |
| Dryad Sportswear Limited | Wholesale & retail | 2020 |
| Duggan Properties Limited | Real estate | 2025 |
| DWR Engineering Limited | Agriculture & fishing | 2021 |
| Dymond Thomas Holdings CYF. | Real estate | 2022 |
| Dynamic Power Systems Limited | Professional & scientific | 2017 |
| E.O.S. Property Management Limited | Other services | 2014 |
| E.W.T Jones Property Limited | Construction | 2024 |
| E.W.T. Jones Groundworks & Civil Engineering Limited | Construction | 2021 |
| Easy Admin Limited | Administrative & support | 2019 |
| Ecological Services Ltd | Professional & scientific | 2018 |
| Economics for Business Limited | Professional & scientific | 2016 |
| Ecotech Energy Solutions Limited | Professional & scientific | 2009 |
| Edgy Services Limited | Real estate | 2021 |
| Edwin Capital Limited | Transport & logistics | 2014 |
| Effergy Consulting Limited | Administrative & support | 2026 |
| EH Accountancy Ltd | Professional & scientific | 2013 |
| Eiran Civil Engineering Limited | Construction | 1993 |
| Element Active Limited | Arts & recreation | 2016 |
| Elementary Trade Marketing Ltd | Professional & scientific | 2025 |
| Eleri Vaughan Ltd | Financial services | 2024 |
| Elliott Financial Ltd | Financial services | 2025 |
| Ellis Island Ltd | Professional & scientific | 2007 |
| Emarket Direct Limited | Wholesale & retail | 2018 |
| Emma Evans Racing Limited | Administrative & support | 2011 |
| Enerlux Limited | Administrative & support | 2008 |
| Ensemble Devices Limited | Professional & scientific | 1996 |
| Enviroactive Limited | Water & waste | 2004 |
| Enviroparks (Hirwaun Properties) Limited | Construction | 2006 |
| Enviroparks (Hirwaun) Limited | Water & waste | 2005 |
| Enviroparks (Wales) Limited | Water & waste | 2009 |
| Enviroparks Bond II Limited | Financial services | 2015 |
| Enviroparks Bond III Limited | Financial services | 2015 |
| Enviroparks Bond IV Limited | Financial services | 2015 |
| Enviroparks Bond Limited | Professional & scientific | 2013 |
| Enviroparks Bond V Limited | Financial services | 2016 |
| Enviroparks Community Liaison C.I.C. | Administrative & support | 2010 |
| Enviroparks Ltd | Professional & scientific | 2007 |
| Enviroparks Operations Limited | Energy | 2014 |
| Envirotrade Ltd | Water & waste | 2007 |
| Epasal Limited | Wholesale & retail | 2013 |
| Epiphanies LLP | | 2006 |
| ESA Assets Ltd | Real estate | 2025 |
| Esw-Design Ltd | Professional & scientific | 2023 |
| Eton Automotive Ltd | Wholesale & retail | 2019 |