| Duafe Digital Ltd | Professional & scientific | 2023 |
| Duckpool Convenience Store Ltd | Wholesale & retail | 2022 |
| Duckpoolcafe Ltd | Hospitality | 2025 |
| Ducks Catering and Events Ltd | Hospitality | 2025 |
| Ductwork Services (IOW) Limited | Construction | 2007 |
| Dudkowiak Fitness Pro Limited | Wholesale & retail | 2015 |
| Duffryn Community Link | Health & social care | 2006 |
| Duffy Tunnelling (South Wales) Limited | Construction | 2008 |
| Duffys-Developments Ltd | Real estate | 2024 |
| Dugmore Commercial Repairs Ltd | Wholesale & retail | 2026 |
| Dukeswood Properties Limited | Construction | 2014 |
| Dumani and Daughters Ltd | Wholesale & retail | 2025 |
| Duncan Yachting Limited | Transport & logistics | 2005 |
| Dunne Property Investment and Management Limited | Other services | 2019 |
| Dunsbury LLP | | 2025 |
| Dunstone Developments Ltd | Construction | 2020 |
| Duodrive Limited | Manufacturing | 2003 |
| Duplex Real Estates Limited | Real estate | 2022 |
| Durableweave Outdoors Limited | Wholesale & retail | 2025 |
| Duralloy Trading Limited | Manufacturing | 2017 |
| Duran Property Group Limited | Real estate | 2025 |
| Durant Investments Ltd | Real estate | 2020 |
| Dust Bunny Cleaning Services South Wales and Bristol Ltd | Administrative & support | 2025 |
| Dust Divas Limited | Administrative & support | 2020 |
| Dutton & Cadwell Limited | Construction | 2002 |
| DVL Financial Services Ltd | Professional & scientific | 2026 |
| DW Construction IW Ltd | Construction | 2018 |
| DW Locksmiths Ltd | Wholesale & retail | 2026 |
| DW Paraplan Limited | Financial services | 2024 |
| DW Properties IW Ltd | Real estate | 2025 |
| DW987 Ltd | Construction | 2024 |
| DWJ Properties Limited | Manufacturing | 2017 |
| DWR Plastics Ltd | Wholesale & retail | 2018 |
| DX Vasi Limited | Transport & logistics | 2026 |
| Dylott Consulting Limited | Professional & scientific | 2022 |
| Dyna Rigging Ltd | Arts & recreation | 2024 |
| Dynamic Catering (Holdings) Limited | Financial services | 2024 |
| Dynatex Limited | Manufacturing | 2018 |
| Dyoni Ltd | Information & communication | 2025 |
| Dyslecsia Cymru/Wales Dyslexia | Education | 2010 |
| E 2 E Innovations Limited | Administrative & support | 2010 |
| E and J Property Services Limited | Manufacturing | 2022 |
| E C Residents Management Limited | Households | 1997 |
| E T Construction Limited | Construction | 2014 |
| E Waste Management Ltd | Water & waste | 2025 |
| E&A Global Shop Ltd | Wholesale & retail | 2025 |
| E-Squared Engineering Services Limited | Construction | 2022 |
| E.C.O.T. Property Limited | Real estate | 2025 |
| E.R.L Engineering Ltd | Manufacturing | 2022 |
| E2E Telecoms Limited | Information & communication | 2017 |
| E3S Consulting Ltd | Professional & scientific | 2016 |
| EA02 Limited | Arts & recreation | 2022 |
| Eagergala Limited | Construction | 1986 |
| Eagle Eyehealth Limited | Wholesale & retail | 2008 |
| Eagle PR Limited | Professional & scientific | 2010 |
| Eagledwell Ltd | Health & social care | 2022 |
| Eamonn Kilby Decorators Limited | Administrative & support | 2005 |
| Early OFF Lighting Ltd | Arts & recreation | 2024 |
| Early Rise Flat Management Limited | Households | 1992 |
| Earnest & Boyle Ltd | Other services | 2021 |
| Earningthrough Ltd | Information & communication | 2021 |
| Earth Rover Limited | Manufacturing | 2017 |
| East Cowes Property Ltd | Real estate | 2020 |
| East Wiltshire Builders Limited | Construction | 2019 |
| Eastcliff Consulting Ltd | Professional & scientific | 2024 |
| Eastcliff Court (Phase 2) Management Company Limited | Households | 1992 |
| Eastern Valley Chemicals (Holdings) Limited | Financial services | 2014 |
| Eastern Valley Chemicals Limited | Manufacturing | 2001 |
| Eastman Chemical Netherlands Limited | Financial services | 2012 |
| Eastman Chemical Regional UK. | Financial services | 1990 |
| Eastman Chemical Workington Limited | Financial services | 2000 |
| Eastman Company UK Limited | Wholesale & retail | 1996 |
| Eastmore Court Management Limited | Households | 1996 |
| Eastmount Residents Association Limited | Households | 1995 |
| Easy Garden Living Limited | Administrative & support | 2023 |
| Easy Garden Online Ltd | Manufacturing | 2025 |
| Easy Garden Structures Limited | Administrative & support | 2025 |
| Easy Readie Ltd | Education | 2020 |
| Easy Trek Ltd | Wholesale & retail | 2023 |
| Easypost Total Parcel Solutions Limited | Transport & logistics | 2012 |
| EAT & SIP Cardiff Limited | Wholesale & retail | 2026 |
| EAT 3 Ltd | Hospitality | 2024 |
| EAT Fresh IOW Ltd | Hospitality | 2024 |
| Eattrainheal Limited | Arts & recreation | 2026 |
| Eazability Limited | Wholesale & retail | 2003 |
| Ebbw Meadow Management Limited | Households | 2019 |
| Ebint-Services Limited | Wholesale & retail | 2019 |
| EBN Cardiff Limited | Hospitality | 2010 |
| EBO Barbers Newport Limited | Other services | 2024 |
| Eboni Electronics Ltd | Wholesale & retail | 2013 |
| EC Manufacturing Limited | Manufacturing | 2021 |
| EC PUB Management Ltd | Hospitality | 2023 |
| ECD Global Ltd | Construction | 2017 |
| Echelon IT Consulting Ltd | Professional & scientific | 2013 |
| Echo Delta Limited | Administrative & support | 2022 |
| Eclipse (Distributors) Limited | Wholesale & retail | 1994 |
| Eclipse Designs Ltd | Manufacturing | 2016 |
| Eclosion Ltd | Professional & scientific | 2023 |
| Ecmor Property Limited | Real estate | 2022 |
| Eco Beach Ltd | Wholesale & retail | 2020 |