| Dentline Limited | Wholesale & retail | 2015 |
| Derwen Aggregates Ltd | Construction | 1995 |
| Derwen Recycling Limited | Water & waste | 2013 |
| Design Dawgz Ltd | Manufacturing | 2021 |
| Devereux Properties Ltd | Real estate | 2025 |
| DG Decorating & Spraying Ltd | Construction | 2026 |
| DGD Trading Services Ltd | Hospitality | 2021 |
| Dharminy Dental Care Limited | Health & social care | 2017 |
| DHW Psychology Consulting Ltd | Health & social care | 2016 |
| Dial a DAP Taxi's Ltd | Transport & logistics | 2017 |
| Diamond Neil Limited | Hospitality | 2023 |
| Diamondps Ltd | Construction | 2026 |
| Dimecity Ltd | Wholesale & retail | 2024 |
| Dionadair Ltd | Administrative & support | 2026 |
| Direct Market Solutions Limited | Information & communication | 2006 |
| Disco Dough Ltd | Hospitality | 2025 |
| Division Automotive Ltd | Wholesale & retail | 2022 |
| Divisus Limited | Financial services | 2020 |
| DJ Timber Consultancy Limited | Professional & scientific | 2016 |
| Dlis Limited | Construction | 2019 |
| Dllc Rees Limited | Professional & scientific | 2021 |
| DLW Retail Limited | Wholesale & retail | 2014 |
| Dodo ES Limited | Health & social care | 2022 |
| Doherty Contract Services Limited | Construction | 2014 |
| Double P Motors Limited | Wholesale & retail | 1967 |
| Dove Workshop Limited | Education | 1989 |
| Doveflair Limited | Other services | 1994 |
| DP Lewis Ltd | Manufacturing | 2015 |
| DR Eslam Zeghebr Ltd | Wholesale & retail | 2025 |
| DR Samia Salam Ltd | Health & social care | 2012 |
| Draghns Limited | Health & social care | 2024 |
| Dragon Detecting Ltd | Wholesale & retail | 2020 |
| Dragon Freeholds (Wales) Ltd | Real estate | 2020 |
| Dragon Mist Limited | Wholesale & retail | 2015 |
| Dragon Spark Productions Limited | Information & communication | 2014 |
| Dragons ARE US Limited | Professional & scientific | 2019 |
| Dream Aerial, Dance and Acrobatics Ltd | Education | 2025 |
| Drews Services Ltd | Professional & scientific | 2025 |
| Drinks Dispense Limited | Wholesale & retail | 2016 |
| Driveway Doctor Machanic Limited | Wholesale & retail | 2025 |
| DRN Properties Limited | Real estate | 2023 |
| Drop the PEN Ltd | Information & communication | 2020 |
| Drumau Developments Ltd | Construction | 2020 |
| Drumau Properties Ltd | Real estate | 2024 |
| Drurys Lettings Ltd | Real estate | 2018 |
| DSH Electrical Ltd | Construction | 2023 |
| DSH Properties and Estates Ltd | Households | 2025 |
| DT Williams Associates Limited | Administrative & support | 2011 |
| DTM Scenic Carpentry Limited | Construction | 2022 |
| Dudays Properties Ltd | Real estate | 2022 |
| Dulais Valley Miners Welfare Club Ltd | Hospitality | 2025 |
| Dulais Valley Properties Ltd | Real estate | 2024 |
| DW Engineering Services Ltd | Professional & scientific | 2023 |
| Dyal Fish & Fried Ltd | Hospitality | 2024 |
| E & L Autos Ltd | Wholesale & retail | 2024 |
| E & L Property Rentals Ltd | Real estate | 2023 |
| E G Lewis Group Hire Services Ltd | Administrative & support | 2022 |
| E G Lewis Group Industrial Services Ltd | Financial services | 2022 |
| E G Lewis Group Integrated Services Ltd | Financial services | 2022 |
| E G Lewis Group Investment Services Ltd | Financial services | 2022 |
| E G Lewis Group Payroll Services Ltd | Administrative & support | 2021 |
| E. G. Lewis Holdings Limited | Administrative & support | 2010 |
| E.G. Lewis & Company Limited | Construction | 1974 |
| Earlswood Canal Ltd | Other services | 2022 |
| Eastnor House Management Company Limited | Households | 2001 |
| Easy Move Swansea Limited | Transport & logistics | 2020 |
| Eco Connect Network Ltd | Construction | 2020 |
| Ecotekk Limited | Wholesale & retail | 2022 |
| ED Tucker Countryside Services Ltd | Arts & recreation | 2017 |
| Edisblaidd Holdings Limited | Financial services | 2024 |
| Edss Limited | Hospitality | 2017 |
| EGL Puracite Limited | Manufacturing | 2003 |
| EHM Marketing Ltd | Other services | 2019 |
| EIN Cwmni Coed Ltd | Agriculture & fishing | 2022 |
| Ek's Delicious Bakes Ltd | Wholesale & retail | 2023 |
| ELD Developments Limited | Real estate | 2023 |
| ELE Property Limited | Real estate | 2020 |
| Electrical Installation & Testing Service Limited | Construction | 2004 |
| ELEMENT6 Hvac Technical Services Limited | Professional & scientific | 2019 |
| Elevate Employment Services Limited | Administrative & support | 2025 |
| Elite Mechanical Group Limited | Energy | 2026 |
| ELS JD Limited | Information & communication | 2011 |
| EMC Roberts Construction Limited | Construction | 2024 |
| EMG Electrical Ltd | Construction | 2021 |
| Emily Ayres Celebrates Ltd | Other services | 2025 |
| Emmjs Model Management CIC | Education | 2025 |
| Emmporia Limited | Education | 2013 |
| Empire Roofing Contracts Ltd | Construction | 2023 |
| Empowered in Work Community Interest Company | Education | 2024 |
| Emris Consulting Limited | Information & communication | 2015 |
| Enchanted Moments Limited | Arts & recreation | 2025 |
| Energybuild Limited | Mining & quarrying | 2003 |
| Energybuild Mining Limited | Mining & quarrying | 2003 |
| Enfys Foundation | Health & social care | 2003 |
| Enhance Returns Ltd | Real estate | 2018 |
| Enterprise Tyres & Exhausts Ltd | Wholesale & retail | 2003 |
| Entity Bistro Ltd | Hospitality | 2026 |
| Entity Pubs Ltd | Hospitality | 2023 |
| Epicode Software Ltd | Information & communication | 2023 |
| Equipyou Ltd | Administrative & support | 2016 |