| CD Race Designs Limited | Administrative & support | 2017 |
| CDW Financial Solutions Limited | Professional & scientific | 2018 |
| CE Site Services Ltd | Administrative & support | 2023 |
| Cefn Mawr Poultry Limited | Agriculture & fishing | 2010 |
| Cefn Tilla Weddings Limited | Hospitality | 2022 |
| Celandine Limited | Financial services | 2004 |
| Celtic Property Developments Limited | Real estate | 2003 |
| Cemetery Training Services Limited | Other services | 2003 |
| Ceridwen Technologies Limited | Information & communication | 2025 |
| Chandos Hart Ltd | Professional & scientific | 2015 |
| Cheltenham Agricultural Ltd | Professional & scientific | 2024 |
| Chips R US Limited | Hospitality | 2013 |
| CJ Building Maintenance Limited | Construction | 2026 |
| CJ Building Services Limited | Construction | 2023 |
| Claire Ford Legal Limited | Professional & scientific | 2026 |
| Clayton SAP Consulting Limited | Professional & scientific | 2018 |
| Clayton SAP Services Limited | Professional & scientific | 2023 |
| Cloud 9 Business Solutions Ltd | Professional & scientific | 2023 |
| Cloud 9 Estates Ltd | Construction | 2013 |
| Clytha Group RDA Limited | Health & social care | 2008 |
| Cmcg Property Services Ltd | Households | 2022 |
| Coast 2 Coast Consultants Limited | Professional & scientific | 2021 |
| Cognisant Consultants Ltd | Administrative & support | 2010 |
| Cognitive Research Limited | Professional & scientific | 2016 |
| Coleg Gwent Catering Limited | Education | 2016 |
| Collins Motorsport Engineering Limited | Professional & scientific | 2026 |
| Comis Security Limited | Administrative & support | 2008 |
| Computernetworkz Ltd | Information & communication | 2003 |
| Concept Business Solutions Limited | Financial services | 2006 |
| Concussion Legacy Limited | Professional & scientific | 2021 |
| Conos Ltd | Professional & scientific | 2022 |
| Considine Associates LLP | | 2004 |
| CONSTRUCT5883 Limited | Construction | 2014 |
| Constructive Media Limited | Manufacturing | 2003 |
| Coppertree (USK) Limited | Wholesale & retail | 1996 |
| Country Built Limited | Construction | 2023 |
| Country Connect Ltd | Information & communication | 2016 |
| Court Arts Ltd | Wholesale & retail | 2019 |
| Crepello Limited | Construction | 2008 |
| Croeso Veterinary Hospital Limited | Professional & scientific | 2007 |
| Crosscarig Limited | Financial services | 2016 |
| Crown Service Station Ltd | Wholesale & retail | 2019 |
| CSK Carpentry Limited | Arts & recreation | 2017 |
| Cwrt Bryn Derwen Management Limited | Households | 2003 |
| D C Hopkins & Sons Building Contractors Limited | Construction | 2015 |
| D Gascoine Accountants Limited | Administrative & support | 2019 |
| D&C Motors Ltd | Wholesale & retail | 2026 |
| D&S Insight Ltd | Professional & scientific | 2015 |
| Darren Butler Rental Portfolio Ltd | Real estate | 2021 |
| Dave Carne Rail Estimating & BID Support Ltd | Professional & scientific | 2021 |
| Daykins Accountancy Ltd | Professional & scientific | 2011 |
| DE Belle Ltd | Wholesale & retail | 2020 |
| Decourcy House Ltd | Construction | 2019 |
| Denmor Developments Limited | Construction | 2006 |
| Department of Marketing Limited | Professional & scientific | 2016 |
| Deutschworks Ltd | Wholesale & retail | 2022 |
| Developing Future Winners Limited | Other services | 2023 |
| Dewmax Limited | Construction | 2012 |
| DGG Site Services Limited | Construction | 2025 |
| Digby Turner & Company Ltd | Real estate | 2022 |
| Dobson Farms Limited | Extraterritorial | 2012 |
| DPH Civil Engineering Limited | Construction | 2023 |
| Drench Limited | Professional & scientific | 2010 |
| Drop in MED Ltd | Education | 2024 |
| DTD Virtual Shopping Ltd | Administrative & support | 2023 |
| EAI Limited | Information & communication | 2002 |
| Echofal Communications Limited | Professional & scientific | 2025 |
| Effective Law Management Limited | Professional & scientific | 2019 |
| EFS Property Ltd | Real estate | 2020 |
| Elmwood Property Holdings Limited | Real estate | 2018 |
| Elstons Estate Agents Limited | Real estate | 2014 |
| Empire Asia Group Company Ltd | Professional & scientific | 2022 |
| Energy Follows Thought Limited | Health & social care | 2019 |
| Enviroengineers Limited | Manufacturing | 1997 |
| Eprr Solutions Limited | Professional & scientific | 2026 |
| Equable Consulting Ltd | Professional & scientific | 2019 |
| Equijust Limited | Financial services | 1995 |
| ET Actuarial Limited | Administrative & support | 2022 |
| Eurofresh Marketing Limited | Wholesale & retail | 2009 |
| Europe for Schools Ltd | Administrative & support | 1997 |
| European Escalator Solutions Ltd | Manufacturing | 2017 |
| European Refractory Consultants Ltd | Professional & scientific | 2025 |
| Eutopian Estates Limited | Real estate | 2023 |
| Everest Retailers Ltd | Wholesale & retail | 2020 |
| Exec Support Ltd | Professional & scientific | 2011 |
| F.D.Q. Consultancy Ltd | Professional & scientific | 2018 |
| FAB Four Coffee Limited | Wholesale & retail | 2020 |
| FAB Fuel Limited | Manufacturing | 2025 |
| Falcon Inter Teck Limited | Extraterritorial | 1983 |
| Fallowfield Commercial Properties Ltd | Real estate | 2023 |
| Farm Road Developments Ltd | Construction | 2021 |
| Fast Engineering (South Wales) Limited | Manufacturing | 2017 |
| Fast Fluid Power Limited | Wholesale & retail | 2002 |
| Fast Lubricants (South Wales) Ltd | Wholesale & retail | 2021 |
| Felwig Games LLP | | 2013 |
| Fencoat Services Limited | Agriculture & fishing | 2019 |
| Feral Ventures Limited | Information & communication | 2021 |
| Fernwood Technology Limited | Information & communication | 2019 |
| Financial Digital Services Ltd | Information & communication | 2024 |
| Forward Thought Property Ltd | Real estate | 2014 |