| Cwtch Infotech Limited | Information & communication | 2022 |
| Cyanite Pictures Limited | Information & communication | 2021 |
| Cyber Veritas Limited | Information & communication | 2024 |
| Cyberlumeneer Limited | Administrative & support | 2019 |
| Cyberseer Limited | Professional & scientific | 2013 |
| Cyril Freedman Limited | Real estate | 1950 |
| D & C Designs Limited | Wholesale & retail | 2006 |
| D & D Snackfoods Limited | Wholesale & retail | 1995 |
| D & L Hair Products Limited | Wholesale & retail | 2010 |
| D & R Green Investments Ltd | Administrative & support | 2025 |
| D & S Media Solutions Limited | Administrative & support | 2003 |
| D B K Building & Property Maintenance Limited | Construction | 2006 |
| D H Movie Services Ltd | Other services | 2025 |
| D P Plumbing & GAS Ltd | Construction | 2023 |
| D R E Trading Limited | Financial services | 2011 |
| D Salim Medical Service Limited | Health & social care | 2015 |
| D Sani Ltd | Wholesale & retail | 2020 |
| D&D Groundwork&Underpinning Ltd | Construction | 2019 |
| D&L Courier Express Ltd | Transport & logistics | 2017 |
| D&L Squeaky Clean Ltd | Administrative & support | 2023 |
| D&P Digital Ltd | Other services | 2025 |
| D&R Flooring Ltd | Construction | 2013 |
| D&U Consultancy Limited | Education | 2022 |
| D. Matthews Rail Limited | Administrative & support | 2012 |
| D. Porthault UK Limited | Wholesale & retail | 2011 |
| D.Alexander Hair Ltd | Other services | 2024 |
| D.F. (Overseas) Limited | Information & communication | 1971 |
| D.Whitby Bathrooms & Kitchens Ltd | Construction | 2021 |
| D2G IT Limited | Administrative & support | 2012 |
| D2W Limited | Extraterritorial | 2002 |
| D3 Underwood Ltd | Arts & recreation | 2019 |
| DAC Architectural Practice & Associates Limited | Professional & scientific | 2020 |
| Dacosta Consultants Limited | Professional & scientific | 2013 |
| Dada Biopic Limited | Information & communication | 2024 |
| Dadi Compusoft PVT Ltd | Information & communication | 2012 |
| Daffodil Accounting Ltd | Professional & scientific | 2009 |
| Daha UK Ltd | Transport & logistics | 2013 |
| Dahm Consulting Limited | Professional & scientific | 2017 |
| Daily Dash UK Limited | Wholesale & retail | 2024 |
| Daily Dispxtch Ltd | Other services | 2021 |
| Daisy Express Ltd | Wholesale & retail | 2025 |
| Daisy Goodwin Productions Limited | Information & communication | 1997 |
| Daisy RAE Limited | Professional & scientific | 2018 |
| Dajr Ltd | Professional & scientific | 2021 |
| Daksa Properties Limited | Real estate | 2021 |
| Dalgagi Limited | Real estate | 2021 |
| Dallas Household Limited | Wholesale & retail | 2022 |
| Dalzell Studio Limited | Information & communication | 2017 |
| DAM Construction Products Limited | Manufacturing | 2024 |
| Damianos Auto Exports Ltd | Wholesale & retail | 2018 |
| Damico One Ltd | Hospitality | 2024 |
| DAN Kraines Marketing Limited | Professional & scientific | 2023 |
| DAN Smith Photography Ltd | Professional & scientific | 2008 |
| Danaila Ltd | Construction | 2021 |
| Dandia Limited | Real estate | 2017 |
| Danela Ezekiel & Associates Ltd | Professional & scientific | 2021 |
| Danely Dispatch LLP | | 2016 |
| Danflo Ltd | Construction | 2022 |
| Daniel Bloomfield Wealth Management Ltd | Administrative & support | 2017 |
| Daniel Farshi Limited | Professional & scientific | 2015 |
| Daniel Harrison Developments Ltd | Manufacturing | 2022 |
| Daniel Ryan Consultants Limited | Manufacturing | 2015 |
| Daniel Woodroffe Group Ltd | Construction | 2024 |
| Daniela Roxana Molnar Solutions Limited | Professional & scientific | 2018 |
| Danish Chamudot Limited | Extraterritorial | 2016 |
| Danlock Limited | Real estate | 1996 |
| Danno Media | Other services | 2016 |
| Dansco Gallery Limited | Administrative & support | 2026 |
| Dansco Holdings Ltd | Administrative & support | 2024 |
| Dany Home Construction Ltd | Construction | 2022 |
| DAP Limited | Professional & scientific | 2001 |
| DAR Builders Ltd | Construction | 2025 |
| Dara Enterprises Limited | Construction | 2024 |
| Dara Huang Ltd | Other services | 2020 |
| Darius Sair Limited | Health & social care | 2020 |
| Darlex Services Limited | Construction | 2011 |
| Darlington Neurological Care Centre Ltd | Administrative & support | 2016 |
| Darreul Sewell Ltd | Health & social care | 2021 |
| Dars of Hempstead Limited | Wholesale & retail | 2018 |
| Dary-Seb Ltd | Transport & logistics | 2015 |
| DAS Accounting Services Ltd | Professional & scientific | 2010 |
| Dasan Capital Ltd | Administrative & support | 2025 |
| Dasan Equity Partners Ltd | Financial services | 2024 |
| Dascalu Construction Ltd | Construction | 2012 |
| Dasch Communications Ltd | Professional & scientific | 2011 |
| DAT Railway Engineering Services Ltd | Information & communication | 2025 |
| Data Corner Ltd | Professional & scientific | 2026 |
| Data ID Ltd | Professional & scientific | 2008 |
| Datacavern Limited | Information & communication | 2011 |
| Datamatiq Consulting Ltd | Information & communication | 2021 |
| Davco Interiors Ltd | Construction | 2013 |
| Davelopware Limited | Information & communication | 2007 |
| Davi's Delivery Ltd | Transport & logistics | 2021 |
| David Abrahams Photography Ltd | Professional & scientific | 2019 |
| David Contractors Limited | Construction | 2018 |
| David Frost Enterprises Limited | Information & communication | 1968 |
| David Glover Sound Limited | Administrative & support | 2013 |
| David Hodges Limited | Information & communication | 2008 |
| David Paradine Limited | Arts & recreation | 1961 |
| David Paradine Productions Limited | Information & communication | 1966 |