| Corporate Golf Limited | Arts & recreation | 2016 |
| Cosmic Ventures Limited | Real estate | 2023 |
| Counsell Financial Consulting Ltd | Professional & scientific | 2020 |
| Counter Current Media Ltd | Information & communication | 2026 |
| Country Clutter Limited | Wholesale & retail | 2003 |
| Country Colour Limited | Information & communication | 1995 |
| Country Swift Properties Limited | Real estate | 2024 |
| County Marquees Limited | Administrative & support | 1990 |
| Coveiro Ltd | Arts & recreation | 2022 |
| Cpk-Roofing Ltd | Construction | 2026 |
| Cracon Ltd | Information & communication | 2022 |
| Crafty Jackal Enterprises Ltd | Information & communication | 2015 |
| Crazel Productions Ltd. | Information & communication | 2015 |
| Creative Equity Venture Partners GP Ltd | Financial services | 2026 |
| Creative Makers Initiative CIC | Arts & recreation | 2025 |
| Creo Medical Group PLC | Manufacturing | 2016 |
| Creo Medical Innovations Limited | Professional & scientific | 2018 |
| Creo Medical Limited | Professional & scientific | 2003 |
| Cricklands Limited | Arts & recreation | 2002 |
| Cromwell Court (Newport) Limited | Households | 1992 |
| Cross Keys Court RTM Company Ltd | Households | 2024 |
| Crossway Green Consulting Ltd | Professional & scientific | 2021 |
| Cruise Cafe Ltd | Hospitality | 2025 |
| Cruise Ship Down Ltd | Information & communication | 2026 |
| Cstim Limited | Professional & scientific | 2017 |
| Cunliffe Analytics Ltd | Professional & scientific | 2010 |
| Cure&Co Beauty Ltd | Other services | 2024 |
| Custom Cleaning ZR Ltd | Administrative & support | 2024 |
| Cutz Hair & Beauty Ltd | Other services | 2025 |
| D&B Tree Services Limited | Agriculture & fishing | 2021 |
| D. Zigmond Limited | | 1947 |
| DA Keedwell Ltd | Real estate | 2024 |
| DAB Newport Ltd | Construction | 2020 |
| Daft Doris Limited | Information & communication | 2019 |
| Daisy Chain Cafe Ltd | Manufacturing | 2025 |
| Damp Bear Limited | Wholesale & retail | 2025 |
| Daniel Fowkes Furniture Ltd | Arts & recreation | 2019 |
| Danielle Berry Expert Witness Limited | Health & social care | 2026 |
| Dark Arts Digital Limited | Professional & scientific | 2017 |
| Dark Smarts Limited | Information & communication | 2025 |
| David Eisenhofer Ltd | Information & communication | 2026 |
| David J Brice Limited | Information & communication | 2002 |
| David's Property Development Ltd | Construction | 2017 |
| Day of the Cacti Limited | Agriculture & fishing | 2018 |
| Dayhouse Holdings Limited | Real estate | 2021 |
| Daytona Interiors Ltd | Manufacturing | 2022 |
| Dean Farm Trust | Administrative & support | 2007 |
| Dean's Auto Repairs Limited | Wholesale & retail | 2009 |
| Deep Institute Limited | Transport & logistics | 2024 |
| Deep Operations UK Ltd. | Financial services | 2026 |
| Deep Research Labs Limited | Professional & scientific | 2023 |
| Dell View (Chepstow) Management Company Limited | Real estate | 1984 |
| Delve Underground UK Limited | Professional & scientific | 2026 |
| Derek Stone Financial Services Limited | Financial services | 2019 |
| Design Incite Ltd | Information & communication | 2015 |
| Devauden Festival Limited | Arts & recreation | 2025 |
| Dhwc Ltd | Professional & scientific | 2022 |
| Different Think Ltd | Professional & scientific | 2020 |
| Digby Civils Limited | Construction | 1992 |
| DIP EAT Greek Ltd | Hospitality | 2025 |
| Dirty Dozen Productions UK Ltd | Information & communication | 2023 |
| Dispute Capital Partners Ltd | Administrative & support | 2019 |
| Diyer Berber Shop Ltd | Other services | 2021 |
| DJS Civils Ltd | Administrative & support | 2025 |
| DNM Design Limited | Manufacturing | 2015 |
| Dobtec Ltd | Information & communication | 2026 |
| Dodo & Bean Ltd | Manufacturing | 2025 |
| Doeth Advisory Ltd | Information & communication | 2025 |
| Doing Good Catering Ltd | Hospitality | 2019 |
| Dolce Vita Calne Limited | Hospitality | 2017 |
| Doll's House Productions Limited | Information & communication | 2013 |
| Dolls Property Limited | Real estate | 2025 |
| Dotiau Ltd | Professional & scientific | 2020 |
| Dough Nation Ltd | Hospitality | 2025 |
| DP Events Ltd | Hospitality | 2025 |
| DR Mckenzie Evans Ltd | Administrative & support | 2013 |
| DR Rhodri Thomas Limited | Health & social care | 2018 |
| DR Swede Limited | Other services | 2016 |
| Dragon Fitness Equipment Ltd | Manufacturing | 2023 |
| Dragon Public Relations Limited | Professional & scientific | 2009 |
| Dragon Zone Ltd | Arts & recreation | 2026 |
| Dragonfly Consultancy Services Limited | Professional & scientific | 2020 |
| Dreadforge Limited | Real estate | 2024 |
| Dream Clean Team Monmouthshire & the WYE Valley Ltd | Administrative & support | 2020 |
| Drip Haus Events Ltd | Hospitality | 2019 |
| Drone Clean Ltd | Administrative & support | 2024 |
| Drovefax Computers Limited | Information & communication | 1983 |
| DS Group (Real Estate) Ltd | Real estate | 2020 |
| Dynexus Consulting Limited | Professional & scientific | 2026 |
| E Hodges Consulting Ltd | Professional & scientific | 2023 |
| E K Tyres Chepstow Limited | Wholesale & retail | 2008 |
| E R System Design Limited | Information & communication | 2006 |
| E-Vap Station Limited | Wholesale & retail | 2016 |
| Earlford Limited | Hospitality | 2007 |
| Earlraden Ltd | Wholesale & retail | 2025 |
| Earlswood Equestrian Limited | Other services | 2019 |
| Eastern Chep Ltd | Hospitality | 2019 |
| Eastville Cars Bristol Ltd | Wholesale & retail | 2018 |
| Easy Garage Services Limited | Wholesale & retail | 2016 |
| Easy Golf Tours Limited | Administrative & support | 2019 |