| DJD Construction Services Limited | Construction | 2020 |
| DJK2 Consulting Ltd | Professional & scientific | 2025 |
| DL Nails & Beauty Ltd | Other services | 2024 |
| DO Idea Co Ltd | Professional & scientific | 2019 |
| Dog Adventure Land Ltd | Other services | 2020 |
| Dominic James Automotive Ltd | Administrative & support | 2026 |
| Dotshouse Limited | Information & communication | 2024 |
| Downs-Side Riding Centre Limited | Arts & recreation | 2014 |
| DPH Management Services Ltd | Professional & scientific | 2012 |
| DR G Lazarus Limited | Health & social care | 2019 |
| DR MO Limited | Health & social care | 2015 |
| DR T Kinnaird Limited | Health & social care | 2011 |
| Dragon Electrics Ltd | Construction | 2018 |
| Dragon GAS & Electrics Ltd | Construction | 2019 |
| Dragon Locums Limited | Information & communication | 2009 |
| Dragon Motorcycles Ltd | Wholesale & retail | 2016 |
| Dragon Property Ventures Ltd | Real estate | 2025 |
| Dragon Respiratory Training Academy Ltd | Education | 2024 |
| Dragonfly Training Limited | Education | 2002 |
| Dragonvale Property Ltd | Real estate | 2026 |
| Draig Athletig CYF | Arts & recreation | 2024 |
| Dream Learn DO CIC | Education | 2023 |
| Drew Energy Ltd | Professional & scientific | 2023 |
| Drew Peacocks Ltd | Construction | 2026 |
| Driveways in Cardiff Limited | Construction | 2021 |
| Dryden Road Penarth Limited | Households | 2017 |
| DTO Property Ltd | Real estate | 2025 |
| Dupa Innovation Ltd | Professional & scientific | 2011 |
| DW Transportation Limited | Professional & scientific | 2011 |
| Dwelling Dynamic Ltd | Real estate | 2025 |
| Dwki Ltd | Construction | 2023 |
| Dynamic Revolt Limited | Wholesale & retail | 2023 |
| Dyscovered Community Interest Company | Education | 2025 |
| East Street D C Ltd | Health & social care | 2018 |
| Easyeat Company Limited | | 1990 |
| Easyliving Assets Limited | Extraterritorial | 2017 |
| Easyliving Limited | Real estate | 2011 |
| Easyliving Rentals Limited | Real estate | 2024 |
| EBM Holdings Ltd | Financial services | 2020 |
| Echalk Ltd | Education | 2003 |
| Eco Home Clean Limited | Administrative & support | 2016 |
| Ecom Digital Limited | Information & communication | 2010 |
| Edascend Ltd | Information & communication | 2025 |
| Eden Landscapes Ltd | Administrative & support | 2003 |
| Edenbrook (Ystradowen) Management Company Limited | Households | 2015 |
| Edisand Ltd | Real estate | 2018 |
| Edit Interiors Group Ltd | Construction | 2023 |
| Edpo Properties Limited | Real estate | 2021 |
| Edtech Assurance Ltd | Education | 2026 |
| Educall Limited | Education | 2017 |
| Educom Consulting Ltd | Professional & scientific | 2025 |
| Edward Davies Properties Limited | Professional & scientific | 1973 |
| Edward England Wharf Management Company Limited | Households | 2004 |
| EFA Freehold Limited | Real estate | 2016 |
| Effective Waste Solutions Limited | Water & waste | 2026 |
| EJL2 Ltd | Arts & recreation | 2026 |
| Ejoy Consultancy Services Ltd | Professional & scientific | 2020 |
| EKB Carpentry Ltd | Manufacturing | 2018 |
| EKF Diagnostics Holdings PLC | Professional & scientific | 2002 |
| Ekho Ltd | Manufacturing | 2023 |
| ELB Contractors Ltd | Construction | 2015 |
| ELB Optical Limited | Health & social care | 2017 |
| Elements Energy Ltd | Energy | 2020 |
| Elevates Social Limited | Professional & scientific | 2026 |
| Ellen Catering Ltd | Hospitality | 2013 |
| Embassy Offices Limited | Administrative & support | 2019 |
| Employment Practice Solutions Limited | Real estate | 2002 |
| Emporium Consultants Limited | Real estate | 1996 |
| Empower ALL Training Ltd | Health & social care | 2025 |
| ENA Cardiff Limited | Hospitality | 2021 |
| Ener-Chi Organics Ltd | Wholesale & retail | 2012 |
| Energetic Engagements Limited | Arts & recreation | 2020 |
| Enlli Associates Limited | Administrative & support | 2008 |
| Epop Holdings Ltd | Financial services | 2026 |
| Erw'R Delyn Residents' Association Limited | Households | 2006 |
| Etheridge Property Investment and Management Ltd | Real estate | 2023 |
| Etronics Limited | Wholesale & retail | 2023 |
| Eureka Escape Limited | Arts & recreation | 2019 |
| EVA DE Brett Ltd | Professional & scientific | 2025 |
| Evans Architectural Ltd | Professional & scientific | 2018 |
| Evans Holdco Limited | Financial services | 2025 |
| Evans Real Estate Consultants Ltd | Real estate | 2022 |
| Evolve Training Club Limited | Other services | 2025 |
| Excel Leisure Ltd | Hospitality | 2013 |
| Exitus Escape Rooms Limited | Arts & recreation | 2018 |
| Exitus Immersive Limited | Hospitality | 2025 |
| Expalum UK Limited | Wholesale & retail | 2020 |
| Expertees Limited | Professional & scientific | 1991 |
| Fabjela Ltd | Households | 2025 |
| Facade Inspections Limited | Construction | 2018 |
| Fairfield Horizon Ltd | Real estate | 2019 |
| FAN Harrhy Law Limited | Professional & scientific | 2021 |
| Fan-Watkins Holding Limited | Financial services | 2026 |
| Fauvette Ltd | Wholesale & retail | 2016 |
| FBP Technology Ltd | Information & communication | 2025 |
| FDO Medical Group Ltd | Health & social care | 2025 |
| Fflur James Limited | Health & social care | 2024 |
| Fiction ET Limited | Arts & recreation | 1994 |
| Filbrit International Academy UK Ltd | Education | 2020 |
| Filbrit Training Centre Ltd. | Education | 2018 |