| Diazo Commercial Ltd | Real estate | 2022 |
| Diazo Holdings Ltd | Real estate | 2020 |
| Diban Bakery Limited | Manufacturing | 2020 |
| Diban Beverages Ltd | Wholesale & retail | 2001 |
| Diban Recycle Ltd | Water & waste | 2019 |
| Dice Consortium CIC | Professional & scientific | 2020 |
| Diego Bucciero Studio Ltd | Professional & scientific | 2024 |
| DIFFERENT8 Ltd | Professional & scientific | 2010 |
| Digicate Ltd | Manufacturing | 2022 |
| Digiglu Ltd | Information & communication | 2018 |
| Digiowl Limited | Wholesale & retail | 2024 |
| Digisolve Ltd. | Professional & scientific | 1995 |
| Digital Change Adventures Ltd | Information & communication | 2022 |
| Digriz Consulting Limited | Information & communication | 2014 |
| Diku Properties Limited | Real estate | 2005 |
| Dilly Holdings Limited | Financial services | 2025 |
| Dinneen Consulting & Co. Ltd | Professional & scientific | 2017 |
| Dinner With Lucifer Productions Limited | Information & communication | 2014 |
| Direct Auto Services (UK) Ltd | Wholesale & retail | 2013 |
| Direct Travel UK Ltd | Transport & logistics | 2005 |
| Directory Solutions Ltd | Other services | 2017 |
| Disabled Enabled Limited | Other services | 2000 |
| Disabledgo Ltd | Financial services | 2024 |
| Discount Tyres Limited | Wholesale & retail | 1980 |
| Discount Wholesale Tyres (Hemel) Limited | Wholesale & retail | 1980 |
| Disha Energy Consultants Limited | Information & communication | 2011 |
| Distinctly Different Days Limited | Administrative & support | 2004 |
| Distinctly Different Designs Limited | Administrative & support | 1995 |
| Distinctly Different Dwellings Limited | Real estate | 2025 |
| Distribution FM Limited | Financial services | 2013 |
| Distribution Hygiene Services Limited | Administrative & support | 2009 |
| Diva CT Trading Limited | Other services | 2025 |
| Divine Cleaning & Household Services Limited | Administrative & support | 2023 |
| DJH Innovations Ltd. | Wholesale & retail | 2024 |
| DJL Electrical Limited | Construction | 2024 |
| Djlow Technical Services Ltd | Professional & scientific | 2024 |
| DJW Recruitment Ltd | Administrative & support | 2025 |
| DK.5 Limited | Construction | 2003 |
| DL Coaching & Retail Ltd | Wholesale & retail | 2025 |
| Dlekker Ltd | Financial services | 2026 |
| DLM Auto Services Ltd | Wholesale & retail | 2025 |
| DLM Consulting (UK) Ltd | Construction | 2013 |
| DM Telecom Limited | Administrative & support | 2018 |
| DMB Express Logistics Ltd | Transport & logistics | 2023 |
| DMB Plastering Specialists Ltd | Construction | 2017 |
| DMM Enterprises Limited | Financial services | 2022 |
| DMS Visuals Limited | Professional & scientific | 2023 |
| Dndh Construction Ltd | Construction | 2024 |
| Dobson Brown Limited | Construction | 2013 |
| Dobson-Brown Services Ltd | Construction | 2020 |
| Dodds Plumbing, Heating & GAS Limited | Administrative & support | 2006 |
| Dodds Rentals Ltd | Real estate | 2018 |
| Dogan Catering Limited | Hospitality | 2012 |
| Dogbonding Ltd | Professional & scientific | 2025 |
| Dogzpaw Ltd | Professional & scientific | 2024 |
| Dolby Digital Solutions Ltd | Information & communication | 2026 |
| Domum Investments Limited | Construction | 2013 |
| DON Giuseppe's Limited | Hospitality | 2021 |
| Donlon Limited | Construction | 2005 |
| Donna Mills Consultancy Limited | Real estate | 2025 |
| Doolittle Pension Administration Limited | Financial services | 2019 |
| Doolittle Trustees Limited | Extraterritorial | 2019 |
| Doris Estates Limited | Real estate | 2022 |
| DOT Big Ledger Ltd | Wholesale & retail | 2025 |
| Dove Healthcare Limited | Health & social care | 2015 |
| Dowding Design Limited | Professional & scientific | 2018 |
| Dower Court Management (Hitchin) Limited | Households | 1988 |
| Down to Earth Tree Services Ltd | Extraterritorial | 2024 |
| Downing Corporate Compliance Limited | Administrative & support | 2007 |
| DPB Holdings Limited | Real estate | 2024 |
| DPG Construction & Services Limited | Construction | 2012 |
| DPH Media Limited | Information & communication | 2017 |
| DPM Direct Ltd | Manufacturing | 2026 |
| DPS Group Lettings Ltd | Real estate | 2018 |
| DPS Heating & Plumbing Ltd | Construction | 2017 |
| DR D. ED Psych Ltd | Education | 2025 |
| DR M Schuhwerk Ltd | Health & social care | 2015 |
| DR W Muller Ltd | Health & social care | 2014 |
| Dragon Maple Solutions Limited | Administrative & support | 2016 |
| Dragon Mews Management Limited | Households | 2021 |
| Dragon MKL Ltd | Administrative & support | 2025 |
| Dragon Print and Design Ltd | Administrative & support | 2008 |
| Dragontale Publishing Limited | Information & communication | 2024 |
| Drainage Fittings Online Limited | Wholesale & retail | 2024 |
| Drainiac Ltd | Water & waste | 2023 |
| DRB Electrical Contractors Ltd | Construction | 2019 |
| DRB Holding Services Limited | Financial services | 2024 |
| DRB Property Management Ltd | Real estate | 2021 |
| Dream Homes Hertfordshire Group Limited | Real estate | 2020 |
| Dream Homes Hertfordshire Limited | Construction | 2009 |
| Dream Reality Holdings Ltd | Financial services | 2020 |
| DRH Sports Limited | Arts & recreation | 2015 |
| Dried Flowers & Decor Ltd | Wholesale & retail | 2020 |
| Driving Wizards Limited | Education | 2013 |
| Dropoutblueprint Limited | Information & communication | 2025 |
| Drummond Group Limited | Financial services | 2015 |
| Drummond Hearing Limited | Health & social care | 2011 |
| Drurys Engineering Limited | Manufacturing | 2024 |
| Dryfast Limited | Wholesale & retail | 2024 |
| DS Plumbing Limited | Construction | 2014 |