| Dadmin Trading Limited | Wholesale & retail | 2017 |
| Daily Bible Declarations Ltd | Wholesale & retail | 2026 |
| Daisy Catering Ltd | Hospitality | 2022 |
| Daisychain Investments Ltd | Wholesale & retail | 2022 |
| Dalmarni Limited | Professional & scientific | 1977 |
| Damiau Ltd | Real estate | 2018 |
| DAN Macey Limited | Professional & scientific | 2020 |
| Dani & Iuliana Ltd | Transport & logistics | 2015 |
| Daniel Truman Racing Limited | Administrative & support | 2026 |
| Danio Car Solutions Ltd | Wholesale & retail | 2025 |
| Danowl Designs Ltd | Real estate | 2023 |
| Daplan Limited | | 1977 |
| Darian Trans Ltd | Transport & logistics | 2018 |
| Darksoi Limited | Manufacturing | 2005 |
| Darlington James Ltd | Construction | 2024 |
| Data & Business Services Ltd | | 1992 |
| Data Centre Cooling Advisory Ltd | Professional & scientific | 2025 |
| Data Harvest Group Limited | Manufacturing | 1985 |
| Data Harvest Limited | Extraterritorial | 1982 |
| Data Network Solutions Ltd | Other services | 2020 |
| Data Stack Consultants Limited | Information & communication | 2025 |
| Datachip Solutions Ltd | Information & communication | 2019 |
| Datahive Limited | Information & communication | 2020 |
| Datanet Communications Solutions Ltd | Manufacturing | 2017 |
| Datascout Limited | Information & communication | 2007 |
| Datashift Ltd | Information & communication | 2022 |
| Dave Mclernon Brickwork Limited | Construction | 2020 |
| Dave Whyte Animations Limited | Arts & recreation | 2002 |
| David Brennan Ltd | Information & communication | 2015 |
| David James Morgan Ltd | Professional & scientific | 2024 |
| David Smith Limited | Wholesale & retail | 2024 |
| David.Live Ltd | Professional & scientific | 2026 |
| Davies Arboriculture Ltd | Professional & scientific | 2024 |
| Davvids Ltd | Construction | 2019 |
| Dbstructural Limited | Professional & scientific | 2015 |
| DC Grill Limited | Manufacturing | 2025 |
| DC Smith Electrical Limited | Wholesale & retail | 2014 |
| DCL (Services) Ltd | Manufacturing | 2013 |
| DCN Communications Ltd | Information & communication | 2011 |
| DDC Consultants Ltd | Information & communication | 2020 |
| Ddfl Carpentry Ltd | Manufacturing | 2021 |
| Ddna Investments Limited | Real estate | 2024 |
| Ddna Properties Limited | Real estate | 2016 |
| Ddna Surrey Investments Limited | Real estate | 2024 |
| DDT Logistics Ltd | Wholesale & retail | 2024 |
| De-Care Limited | Health & social care | 2023 |
| Deadline Services Limited | | 1986 |
| Dealway Limited | Professional & scientific | 1988 |
| Dean J Arnold Ltd | Construction | 2023 |
| Dean Mcdonagh Consultancy Limited | Information & communication | 2019 |
| Decord Limited | Wholesale & retail | 2022 |
| Deep Abacus Ltd | Administrative & support | 2020 |
| Deep Kleen Luton Ltd | Administrative & support | 2010 |
| Deepmuse Limited | Information & communication | 2024 |
| Dees Cards Limited | Wholesale & retail | 2002 |
| Deeyoung Care Ltd | Health & social care | 2024 |
| Default Vehicle Collections Limited | Wholesale & retail | 2010 |
| Defence Packaging Ltd | Administrative & support | 2024 |
| Delafield Consulting Limited | Professional & scientific | 2014 |
| Delia Decorating & Tiling Ltd | Construction | 2020 |
| Dell Court (Berkhamsted) Management Company Limited | Households | 2011 |
| Delta Mercury Limited | Wholesale & retail | 2015 |
| Delter Culson Ltd. | Manufacturing | 2012 |
| Denceram Dental Laboratory Limited | Other services | 1997 |
| Denham Property Ltd | Households | 2013 |
| Dennison Electrical Systems Ltd | Real estate | 2004 |
| Denny & Salmond Limited | Real estate | 2004 |
| Denteuro Ltd | Health & social care | 2019 |
| Derby Road (Watford) Management Company Limited | Households | 2005 |
| Derek Mitchell Construction Services Limited | Professional & scientific | 2018 |
| Derndale Properties Limited | Real estate | 1998 |
| Derngate Health Care Limited | Real estate | 1992 |
| Derryquin Limited | Real estate | 2014 |
| Design Wood LAB Limited | Manufacturing | 2023 |
| Designed & Developed Limited | Manufacturing | 2020 |
| Dessertoutletuk Ltd | Wholesale & retail | 2023 |
| Destinato Limited | Professional & scientific | 2024 |
| Detail Squared Limited | Professional & scientific | 2010 |
| DEV Traders Limited | Wholesale & retail | 2023 |
| Devrel Bridge Ltd | Professional & scientific | 2024 |
| Dewaft Limited | Information & communication | 2016 |
| Deyu & Criss Ltd | Transport & logistics | 2018 |
| DGD Consulting Limited | Information & communication | 1997 |
| DGJ Automotive Limited | Professional & scientific | 2025 |
| Dhptfitness Ltd | Arts & recreation | 2021 |
| DIA Green Limited | Construction | 2019 |
| DIA Ventures Ltd | Wholesale & retail | 2021 |
| Diagnostic Services & Repairs Garage Ltd | Wholesale & retail | 2021 |
| Diagonal Consulting Limited | Information & communication | 2018 |
| Diamond Bright Consulting Limited | Professional & scientific | 2011 |
| Diamond Technologies Limited | Information & communication | 2013 |
| Digi Baseline Solutions Ltd | Information & communication | 2026 |
| Digidoda Ltd | Information & communication | 2017 |
| Digilaunch Ltd | Professional & scientific | 2025 |
| Digistudio Limited | Professional & scientific | 2006 |
| Digital Abbey Ltd | Transport & logistics | 2013 |
| Digital Alchemists Ltd | Extraterritorial | 2018 |
| Digital Deconstructed Ltd | Administrative & support | 2025 |
| Digital Delivered Ltd | Information & communication | 2025 |
| Digital Gecko Ltd | Information & communication | 2025 |