| CCS Organisation Ltd | Administrative & support | 2012 |
| CEA Optical Ltd | Wholesale & retail | 2017 |
| Cerberus Ecommerce Marketplace Development Limited | Information & communication | 2023 |
| CFW Properties Ltd. | Real estate | 2015 |
| Chandler Purkess Limited | Agriculture & fishing | 2002 |
| Charlie Davis Ltd | Arts & recreation | 2014 |
| Charlie's Childcare Ltd | Health & social care | 2025 |
| Chinook Two Moons Ltd | Other services | 2014 |
| Chris Jones Property Maintenance Limited | Construction | 2014 |
| Chris Nightingale Limited | Arts & recreation | 2008 |
| Chris W Jones Ltd | Professional & scientific | 2023 |
| Chwiliad CIC | Hospitality | 2025 |
| Cilgwyn Farm Limited | Agriculture & fishing | 2008 |
| Clarian Solutions Ltd | Information & communication | 2025 |
| Clean Seas Technologies Ltd | Manufacturing | 2018 |
| Cleanseat UK Limited | Extraterritorial | 2021 |
| Clearfc Ltd | Professional & scientific | 2020 |
| Clearfinancialconsultants Ltd | Professional & scientific | 2015 |
| Clearhealth Ltd | Health & social care | 2022 |
| Climbing Hands ARB Ltd | Professional & scientific | 2020 |
| Clud Property Limited | Real estate | 2012 |
| CMR Search Ltd | Administrative & support | 2025 |
| Cnewr Estate Limited(The) | Agriculture & fishing | 1955 |
| Coast Autonomous UK Ltd | Information & communication | 2021 |
| Coded Pixel Ltd | Information & communication | 2013 |
| Coffee Box Solutions Limited | Hospitality | 2016 |
| Compass Accommodation Limited | Real estate | 2019 |
| Conficio Ltd | Information & communication | 2019 |
| Context Engineering Limited | Construction | 2003 |
| Corn Exchange Crickhowell Limited | Construction | 2015 |
| Cosi Tabellini UK Limited | Wholesale & retail | 2013 |
| Cradoc Golf Club Limited | Arts & recreation | 2014 |
| Cradoc Golf Club Trading Ltd | Arts & recreation | 2015 |
| Cradoc's Savoury Biscuits Ltd | Manufacturing | 2013 |
| Cribyn Coffee Company Limited | Manufacturing | 2020 |
| CS Streatham Limited | Hospitality | 2010 |
| Cwmni Cynhyrchu THR CYF | Arts & recreation | 2022 |
| Cwrt Y Prior Partners LLP | | 2016 |
| Cyber Wales Group C.I.C. | Professional & scientific | 2020 |
| Cyber Wales Skills Ltd | Information & communication | 2020 |
| Cymrucartel Ltd | Wholesale & retail | 2025 |
| D & M Jones Developers Ltd | Construction | 2016 |
| D J W Lloyd Limited | Agriculture & fishing | 2010 |
| D&J Pubs Ltd | Hospitality | 2022 |
| D&L Thickins Limited | Other services | 2024 |
| D&S Clean and Clear Ltd | Water & waste | 2023 |
| Daily Care Ltd | Health & social care | 2024 |
| Dangerfield Limited | Administrative & support | 2011 |
| Dark Sky Collection Ltd | Hospitality | 2017 |
| Dark Sky Retreat Ltd | Real estate | 2024 |
| Darling Buds Photography Limited | Professional & scientific | 2009 |
| Dart Data Systems Ltd | Extraterritorial | 1995 |
| Data Storage Services Ltd | Information & communication | 2011 |
| Datagator Solutions Ltd | Information & communication | 2024 |
| Dave Horner Limited | Construction | 2002 |
| Davies and Davies LLP | | 2024 |
| DB Action Ltd | Other services | 2022 |
| DC2 Engineering Ltd | Agriculture & fishing | 2012 |
| DCE Group Agency Limited | Manufacturing | 2018 |
| DDS Contracting Ltd | Construction | 2021 |
| Dean Watkins Ltd | Agriculture & fishing | 2012 |
| Dedicate a Tree Ltd | Other services | 2019 |
| Defynnog Mineral Supplies Ltd | Manufacturing | 2026 |
| Defynnog Properties Limited | Real estate | 2011 |
| Degemont Engineering Limited | Administrative & support | 2007 |
| Delboys Baps Brecon Limited | Hospitality | 2024 |
| Deri Allsop Limited | Construction | 2015 |
| DES Foods Ltd | Hospitality | 2024 |
| Deshi Food Wholesale Ltd | Wholesale & retail | 2023 |
| Designcell Architecture Limited | Professional & scientific | 2008 |
| Designer Partners Ltd | Professional & scientific | 2009 |
| Development Services International Limited | Financial services | 2019 |
| Digital Manufacturing Limited | Manufacturing | 2009 |
| Dijk Williams Ltd | Other services | 2024 |
| Discover Collective Ltd | Wholesale & retail | 2022 |
| DM Prosser Limited | Other services | 2010 |
| DMJ Electrical Services Limited | Construction | 2019 |
| Doughlivery Ltd | Manufacturing | 2021 |
| Dozens of Currants Limited | Arts & recreation | 2016 |
| DR MAY Aesthetics Limited | Health & social care | 2021 |
| Dragon Treecare Limited | Other services | 2002 |
| Drew Roofing, Leadwork and Building Ltd | Construction | 2015 |
| DRL Site Services Limited | Professional & scientific | 2002 |
| DRY Back Macs Limited | Agriculture & fishing | 2024 |
| Duncan Skelton Coaching Ltd | Professional & scientific | 2021 |
| DWT Education Ltd | Education | 2024 |
| Dyfed Powys Local Medical Committee Limited | Health & social care | 2011 |
| Dyfed Powys Woodfuels Limited | Administrative & support | 2018 |
| E G Jones & SON Limited | Construction | 2015 |
| E-Scout.Edge.Analytics Ltd | Information & communication | 2024 |
| E.H.M.A. Limited | Real estate | 2013 |
| E.R. East & SON Limited | Wholesale & retail | 1992 |
| Eamoe Financial Services Ltd | Administrative & support | 2025 |
| Earthlykind Ltd | Wholesale & retail | 2020 |
| Earthwise Plumbing & Renewables Ltd | Construction | 2025 |
| Eatdrinksleep Limited | Hospitality | 1999 |
| EB Williams Limited | Professional & scientific | 2017 |
| EBB & Flow Brecon CIC | Other services | 2024 |
| Ecovent Solutions Ltd | Construction | 2008 |
| Eden Development Consultants Ltd | Professional & scientific | 2015 |