| D&B (Flat Pack) Solutions Limited | Other services | 2016 |
| D&B Media Ltd | Information & communication | 2014 |
| D&S Hertford Limited | Health & social care | 2017 |
| Daily 5 Ltd | Information & communication | 2024 |
| Daines Kapp Insurance Brokers Limited | Financial services | 1989 |
| Daintrees Management Company Limited | Households | 1985 |
| Daisy Integral Solutions Ltd | Information & communication | 2018 |
| Daleba Electronics Limited | Wholesale & retail | 1963 |
| Dales Club C.I.C. | Other services | 2021 |
| Daluxe Development Group Ltd | Construction | 2024 |
| DAN Smarts Group Holdings Limited | Financial services | 2024 |
| DAN Smarts Scaffolding Limited | Construction | 2024 |
| Dandelion Education Support CIC | Education | 2025 |
| Dane END Store Convenience Ltd | Wholesale & retail | 2021 |
| Dane END Stores Ltd | Wholesale & retail | 2018 |
| Danebridge Group Limited | Construction | 2018 |
| Daniel & Jacobs Limited | Financial services | 2013 |
| Daniel Frangiamore Ltd | Other services | 2018 |
| Danielle Holt Designs Limited | Professional & scientific | 2022 |
| Daniroja Consulting Limited | Administrative & support | 2017 |
| Danny Taverns Limited | Hospitality | 2017 |
| Data and Digital Science Ltd | Wholesale & retail | 2018 |
| Data Room Supplies Limited | Wholesale & retail | 2004 |
| Datacentre Support Ltd | Professional & scientific | 2024 |
| Datum Phase Change Limited | Construction | 2009 |
| Datum Point Joinery Ltd | Construction | 2021 |
| Dave Head & SON (Plant Hire & Haulage ) Ltd | Construction | 2011 |
| Dave Head & Sons (Civil Engineering Contractors) Ltd | Construction | 2007 |
| Dave Head & Sons Land Regeneration Contractors Ltd | Water & waste | 2017 |
| Davenport Build Limited | Construction | 2020 |
| David Regent Ltd | Professional & scientific | 2015 |
| David Russell Consultancy Limited | Construction | 2007 |
| David Suckling & Co. Limited | Professional & scientific | 2001 |
| Day Carpentry Limited | Manufacturing | 2008 |
| DB Capital Solutions Limited | Energy | 2013 |
| DB Scenic Ltd | Construction | 2024 |
| Dbborthopaedics Ltd | Health & social care | 2025 |
| DD Heating Services Limited | Construction | 2023 |
| DDB Management Solutions Ltd | Administrative & support | 2019 |
| DE Vere Electrical Limited | Construction | 2014 |
| Dean Amoss Contractors Limited | Construction | 2016 |
| Dean of the Dead Ltd | Hospitality | 2021 |
| Dean Sadler Rigging & Services Ltd | Construction | 2025 |
| Deans Furnishers Limited | Wholesale & retail | 1992 |
| Dearman Developments Limited | Construction | 1999 |
| Debden Group Ltd | Construction | 2018 |
| DEC to Spec Limited | Construction | 2012 |
| Defining Features by Charlotte Ltd | Other services | 2023 |
| DEL Design and Drafting Ltd | Professional & scientific | 2026 |
| Delivered Easy Limited | Transport & logistics | 2016 |
| Delphi Perspective Ltd | Professional & scientific | 2024 |
| Deprin Consulting Ltd | Information & communication | 2025 |
| Design'A Face Limited | Arts & recreation | 2017 |
| Detailed Group Ltd | Administrative & support | 2024 |
| Devecops Vince Ltd | Information & communication | 2026 |
| Dewco Services Limited | Real estate | 1974 |
| Dgjrh Property Co. Limited | Financial services | 2024 |
| Dharma Awakenings Limited | Other services | 2023 |
| DHS Anaesthetics Limited | Health & social care | 2023 |
| Diacare Ltd | Health & social care | 2023 |
| Diamond TEQ Limited | Information & communication | 2022 |
| DID YOU Planet? Limited | Wholesale & retail | 2026 |
| Digfat Ltd | Professional & scientific | 2025 |
| Digital Healthcare Management Ltd | Health & social care | 2016 |
| Digitech Commercial Limited | Information & communication | 2017 |
| Direct Carpets & Flooring Ltd | Wholesale & retail | 2018 |
| Direct Labour Hire Limited | Administrative & support | 2004 |
| Direct Social Connections Limited | Information & communication | 2024 |
| Distantstructure Limited | Real estate | 1987 |
| DJ Garage Services Ltd | Wholesale & retail | 2010 |
| DJC Paragon Homes Ltd | Real estate | 2025 |
| DJC Performance Ltd | Arts & recreation | 2025 |
| DJH Contracting Ltd | Construction | 2020 |
| DJI Build Ltd | Construction | 2019 |
| Do&Do UK Ltd | Agriculture & fishing | 2020 |
| Doanythingnow Ltd | Other services | 2023 |
| DOC Carpentry Ltd | Construction | 2023 |
| Dockyard Business and Storage Centres Ltd | Real estate | 2020 |
| DOE Genetics Limited | Wholesale & retail | 2024 |
| DOE Legacy Ltd | Wholesale & retail | 2025 |
| Dogology Dogs Ltd | Other services | 2022 |
| Doherty Civils Limited | Construction | 2023 |
| Doherty Plant & Hire Limited | Administrative & support | 2025 |
| Dollery Family LLP | | 2023 |
| Dolphin Yard Residents Association (Ware) Limited | Households | 1983 |
| Donald Charles Architectural Landscape and Design Limited | Administrative & support | 2013 |
| Douglas Stewart Limited | Administrative & support | 2010 |
| Douglas Stewart Ventures Limited | Professional & scientific | 2009 |
| Dowling Building Services Limited | Construction | 2017 |
| Drainwork Solutions Ltd | Construction | 2015 |
| Drawing Voices Ltd | Arts & recreation | 2022 |
| Dream Public Relations Ltd | Professional & scientific | 2024 |
| Drippin Junkies Apparel Limited | Manufacturing | 2016 |
| Drone Sport International Ltd | Professional & scientific | 2026 |
| Dronetech Aerial Solutions Limited | Information & communication | 2018 |
| Droopy Chaos Ltd | Other services | 2025 |
| Dryswift Ltd | Manufacturing | 2025 |
| Dsco Bookkeeping Limited | Professional & scientific | 2008 |
| Dsco Limited | Professional & scientific | 2008 |
| DSW Servicing Ltd | Wholesale & retail | 2022 |