| Debsho Consulting Ltd | Professional & scientific | 2015 |
| Debt Help Ltd | Financial services | 2017 |
| Debt Managers Standards Association Limited | Other services | 2000 |
| Debt Savvy Ltd | Financial services | 2019 |
| Debunc Ltd | Professional & scientific | 2015 |
| Dec-Tek (Contractors) Limited | | 1985 |
| Decaflux Ltd | Administrative & support | 2025 |
| Decamornt Ltd | Wholesale & retail | 2025 |
| Decani Ltd | Financial services | 2003 |
| Decaro Resin and Flooring Limited | Construction | 2021 |
| Decca Care Limited | Health & social care | 2024 |
| Decco Homes Ltd | Real estate | 2020 |
| Decent Care Services Ltd | Health & social care | 2018 |
| Decent Investment Properties Limited | Hospitality | 2024 |
| Decidedly Dawson Holdings Limited | Professional & scientific | 2020 |
| Decidedly Dawson Ltd | Professional & scientific | 1996 |
| Decise Review Limited | Information & communication | 2021 |
| Deck-Rite Flooring Limited | Construction | 2002 |
| Deckchair Creative Ltd | Professional & scientific | 2021 |
| Deckless Ltd | Information & communication | 2025 |
| Declassified Cymru CIC | Education | 2025 |
| Declercq Holdings Ltd | Financial services | 2024 |
| Deco Heat Ltd | Construction | 2023 |
| Deco Supplies Ltd | Wholesale & retail | 2017 |
| Deco&Post Ltd | Administrative & support | 2017 |
| Decoprazol Ltd | Wholesale & retail | 2023 |
| DECOR8 (Cardiff) Limited | Construction | 2017 |
| DECOR8 INT Ltd | Arts & recreation | 2019 |
| Decora Mart Ltd | Wholesale & retail | 2026 |
| Decorative Gift Articles Ltd | Wholesale & retail | 2024 |
| Decorative Glass & Glazing Co Ltd | Construction | 2000 |
| Decorative Heating Limited | Construction | 2003 |
| Dectek Limited | Manufacturing | 2002 |
| Decyk Enterprises Ltd | Professional & scientific | 2025 |
| Dede Facility Services Limited | Administrative & support | 2026 |
| Dedham Vale Electrical Ltd | Construction | 2014 |
| Dedicated Digital Limited | Arts & recreation | 2025 |
| DEE Production Services Ltd | Information & communication | 2020 |
| Dee's Kitchen Ltd | Hospitality | 2016 |
| Deeconic Ltd | Construction | 2019 |
| Deekshha Consultancy Ltd | Information & communication | 2022 |
| Deelan Health Clinic Ltd | Health & social care | 2020 |
| Deemuir Square Management Company Limited | Households | 2006 |
| Deen Construction Limited | Construction | 2005 |
| Deen's Solutions Limited | Financial services | 2016 |
| Deenik Properties Ltd | Real estate | 2021 |
| Deentown Ltd | Wholesale & retail | 2025 |
| Deep Black Drilling LLP | | 2010 |
| Deep Cleaner Services Ltd | Administrative & support | 2025 |
| Deep Dive Project Ltd | Administrative & support | 2020 |
| Deep Fusion Films Limited | Information & communication | 2023 |
| Deep Iron Saas Ltd | Information & communication | 2025 |
| Deep Learn Human Science Ltd | Information & communication | 2025 |
| Deep Mudhar Ltd | Professional & scientific | 2023 |
| Deep PAY Ltd | Professional & scientific | 2025 |
| Deep Payro Ltd | Professional & scientific | 2025 |
| Deep Planet Limited | Information & communication | 2018 |
| Deep Root Path Ltd | Information & communication | 2025 |
| Deep Tripay Ltd | Professional & scientific | 2025 |
| Deepai Ltd | Information & communication | 2025 |
| Deeplash Ltd | Wholesale & retail | 2019 |
| Deepsea Digital Limited | Information & communication | 2025 |
| Deepzero Software Ltd | Information & communication | 2020 |
| Deerzz Co., Ltd | Manufacturing | 2021 |
| Deeside Lavender Limited | Agriculture & fishing | 2018 |
| Deeti Wholesale Limited | Wholesale & retail | 2015 |
| Deev Global Limited | Information & communication | 2022 |
| Deeval Combustion Equipment Limited | Manufacturing | 2020 |
| Defender BK Ltd | Administrative & support | 2025 |
| Defendx Security Solutions Limited | Administrative & support | 2025 |
| Defi Digits UK Ltd | Information & communication | 2021 |
| Defi Ltd | Wholesale & retail | 2025 |
| Defier Ltd. | Arts & recreation | 2013 |
| Defined Construction Limited | Construction | 2018 |
| Defining Products Limited | Professional & scientific | 2014 |
| Definitive Painting and Decorating Ltd | Construction | 2019 |
| Defne Global Store Ltd | Wholesale & retail | 2024 |
| Defor Limited | Construction | 2022 |
| Deft Recruiter Limited | Administrative & support | 2023 |
| DEG Workshop Ltd | Manufacturing | 1999 |
| Degoat Ventures Ltd | Transport & logistics | 2019 |
| Degorender PC | | 2018 |
| Dehavilland Investments Limited | Real estate | 2020 |
| Deiconsilio Limited | Public administration | 2022 |
| Deicors Ltd | Extraterritorial | 2016 |
| Deido Export Limited | Wholesale & retail | 2024 |
| Deighton Consultants Limited | Professional & scientific | 1996 |
| Deilen Resource Management Ltd | Professional & scientific | 2026 |
| Deintyddfa SWN Y MOR CYF | Health & social care | 2023 |
| Deja VU (Cardiff) Limited | Hospitality | 2008 |
| Deja VU SLV Limited | Real estate | 2026 |
| Deja VU Studio Ltd | Information & communication | 2025 |
| Dejbenterprises Ltd | Wholesale & retail | 2025 |
| Dejil for Exports & Imports Limited | Wholesale & retail | 2017 |
| Deju Renheo Limited | Wholesale & retail | 2025 |
| Dekmouche Ltd | Wholesale & retail | 2025 |
| Dekpen Limited | Wholesale & retail | 2021 |
| Deku Ltd | Financial services | 2025 |
| DEL Arena Management Limited | Administrative & support | 2015 |
| DEL Merchandise Limited | Wholesale & retail | 2015 |