| Daenerys Enterprises Ltd | Real estate | 2024 |
| Dafuq Innovations Ltd | Information & communication | 2019 |
| Daka Distribution Limited | Wholesale & retail | 2012 |
| Daly Grind Ltd | Construction | 2026 |
| DAN Stacey Construction Limited | Construction | 2007 |
| Daniel Miller Electrical Ltd | Construction | 2023 |
| DAR LEW Management Limited | Administrative & support | 2026 |
| Darkblock Ltd | Information & communication | 2021 |
| Darren Burnett Construction Limited | Construction | 2025 |
| Darren Burnetts Enterprise Limited | Financial services | 2025 |
| Dart BTL Limited | Real estate | 2019 |
| Dart SH2 Limited | Information & communication | 2021 |
| Data Causeway Limited | Information & communication | 1996 |
| Dave Powell Limited | Professional & scientific | 2013 |
| Davey Tree Services Ltd | Administrative & support | 2024 |
| David Bearman Limited | Professional & scientific | 2007 |
| David Grinter Associates Ltd | Construction | 2013 |
| Davies Timbers (Wales) Holdings Limited | Financial services | 2020 |
| Davies Timbers (Wales) Limited | Manufacturing | 2003 |
| DAY2DAY Retail Ltd | Wholesale & retail | 2025 |
| Dayon Retail Services Limited | Wholesale & retail | 2018 |
| Dbem Constructii Limited | Construction | 2026 |
| DBL Auto's Ltd | Wholesale & retail | 2024 |
| DBP Portfolio Limited | Real estate | 2025 |
| Decision Support Services (UK) Ltd | Information & communication | 2010 |
| Deen Properties Ltd | Real estate | 2019 |
| Delta Pattern & Tool Co. Limited | Manufacturing | 1984 |
| Demetae Limited | Financial services | 2017 |
| Dennehy Autos Limited | Wholesale & retail | 2025 |
| Derek Pugh(Racing)Limited | Real estate | 1961 |
| Devika Systems Ltd | Information & communication | 2020 |
| DF Chicken Limited | Administrative & support | 2015 |
| DGL Media Agency Limited | Information & communication | 2025 |
| DH Carpentry Services Ltd | Construction | 2026 |
| DHC Automotive Ltd | Wholesale & retail | 2025 |
| DHS Consulting Services Limited | Financial services | 2015 |
| DHS Wealth Investments Ltd | Professional & scientific | 2024 |
| Dido Foods Ltd | Hospitality | 2026 |
| Digiport Computer Solutions Limited | Wholesale & retail | 2025 |
| Dingle Dell Properties Ltd | Households | 2024 |
| Disherbia Ltd | Wholesale & retail | 2025 |
| Diverse Development Solutions Ltd | Real estate | 2024 |
| DJ MOT Centre Limited | Wholesale & retail | 2024 |
| DJ4ADAY CIC | Education | 2026 |
| DJB Heating Limited | Construction | 2023 |
| DK & S Holdings Ltd | Financial services | 2025 |
| DL Administrative Services Limited | Public administration | 2019 |
| DNJ +LJJ Services Ltd | Real estate | 2018 |
| Doctor Windows Limited | Construction | 2015 |
| Donna Stonelake Estate Agents Ltd | Real estate | 2023 |
| Doores Ltd | Real estate | 2022 |
| Douglas Willis Limited | Manufacturing | 2005 |
| Douglas Willis Retail Limited | Wholesale & retail | 2011 |
| Down to Earth Agronomy Limited | Professional & scientific | 2023 |
| DP Engineering (SW) Ltd | Construction | 2022 |
| Dragon Bounce & Events Ltd | Arts & recreation | 2026 |
| Dragon Education Solutions Ltd | Education | 2011 |
| Dragon Executive Academy Ltd | Professional & scientific | 2024 |
| Dragon Executive Management Ltd | Professional & scientific | 2018 |
| Dragon Telecomponents Ltd | Wholesale & retail | 2007 |
| Dramaramaa Ltd | Arts & recreation | 2022 |
| DRL Property Management Ltd | Real estate | 2024 |
| DS Digital Ltd | Information & communication | 2025 |
| Duct Flange UK Limited | Manufacturing | 2016 |
| Dunn IT Ltd | Information & communication | 2023 |
| Dynamic Commercial Cleaning Limited | Administrative & support | 2017 |
| E Gooderham Holdings Ltd | Professional & scientific | 2025 |
| E J Herbert & SON Limited | Administrative & support | 2006 |
| E Jordan Limited | Financial services | 2023 |
| E.J. Metcalfe Limited | Administrative & support | 2002 |
| E.L. & E.R. Jones Limited | Real estate | 1957 |
| Eclat Forensics and Identity Consulting Ltd | Professional & scientific | 2020 |
| Edwards Family Dental Health Centre Ltd | Health & social care | 2026 |
| EFG Energy Limited | Energy | 2026 |
| EFG Food & Tech Holdings Limited | Wholesale & retail | 2005 |
| EGB Consulting UK Ltd | Professional & scientific | 2009 |
| EJH Consultants Ltd | Professional & scientific | 2025 |
| Ekey Solutions Limited | Manufacturing | 2016 |
| EKJ Lettings Limited | Real estate | 2022 |
| Electrical Power Limited | Administrative & support | 2018 |
| Elegant Bathrooms & Precise Tiling Limited | Construction | 2025 |
| Eleven Murray Street Ltd | Real estate | 2025 |
| Elidir Property Ltd | Real estate | 2026 |
| Elif Cwmbran Ltd | Hospitality | 2025 |
| Elisa (Cwmbran) Ltd | Hospitality | 2025 |
| Elite Dispense Solutions Ltd | Other services | 2025 |
| Elite Electrical and Media Walls Ltd | Construction | 2025 |
| Eliza Bear's CYF | Hospitality | 2025 |
| Ell's Lashes Ltd | Wholesale & retail | 2025 |
| Ellerby Homes Ltd | Construction | 2021 |
| Ellie’S Café Limited | Hospitality | 2025 |
| ELS Coaching Ltd | Professional & scientific | 2024 |
| Elwyn & Mabel Estate Planning Ltd | Financial services | 2025 |
| Emmas Lashes CYF | Other services | 2025 |
| Empowerwise Ltd | Health & social care | 2024 |
| Emtec Skills Limited | Education | 2009 |
| Enable Care Services (South Wales) Limited | Health & social care | 2002 |
| Energize Media CIC | Education | 2015 |
| Enhance Training Performance Academy Ltd | Arts & recreation | 2025 |
| Envirobalance UK Ltd | Professional & scientific | 2013 |