| Dand Precast Ltd | Manufacturing | 2009 |
| Dandelion Designs by Mandy Shaw Limited | Wholesale & retail | 2015 |
| Daned Consultancy Services Limited | Mining & quarrying | 2012 |
| Daneholt LLP | | 2012 |
| Darent Valley Healthcare LLP | | 2025 |
| Data Protection and Compliance Services Limited | Information & communication | 2018 |
| David Jordan Estate Agents Limited | Real estate | 2005 |
| David Pointing Brickwork Limited | Construction | 2020 |
| Dawson Property Ventures Ltd | Real estate | 2025 |
| DB10 Holdings Limited | Financial services | 2023 |
| DCL Ventures Limited | Real estate | 2024 |
| Dean Construction (Sussex) Ltd | Construction | 2004 |
| Deanland Business Park (Management) Limited | Real estate | 2012 |
| Deanlands Development Limited | Construction | 2020 |
| Deborah Gage (Works of Art) Limited | Arts & recreation | 1986 |
| Deborah Gage Limited | Arts & recreation | 1981 |
| Deedgate Limited | Real estate | 1988 |
| Delth T/A Local Taxis Hailsham & Private Hire Ltd | Transport & logistics | 2025 |
| Demoncheese Limited | Professional & scientific | 2015 |
| Dent Technics Ltd | Wholesale & retail | 2013 |
| Dental and Maxillofacial Radiology Academy Limited | Education | 2021 |
| Dermis LLP | | 2022 |
| Desert Dancer Productions Ltd. | Information & communication | 2012 |
| Desert Rose Bikes Ltd | Wholesale & retail | 2021 |
| Desert Rose Dirt Tech Limited | Wholesale & retail | 2019 |
| Desert Rose Racing Limited | Administrative & support | 2010 |
| Design Planet Limited | Professional & scientific | 2016 |
| DESIGN4U Ltd | Construction | 2018 |
| Deuco Bathroom Furniture Limited | Wholesale & retail | 2012 |
| Devture Limited | Professional & scientific | 2024 |
| DH Executive Search Limited | Administrative & support | 2025 |
| DH Plastic Surgery Ltd | Health & social care | 2023 |
| DHC (Southern) Limited | Construction | 2026 |
| Diagnostek Limited | Wholesale & retail | 2022 |
| Dias Enterprises Limited | Information & communication | 2015 |
| Dicker Enterprises Limited | Education | 1989 |
| Different Hats Ltd | Administrative & support | 2023 |
| Digiprints UK Limited | Manufacturing | 2004 |
| Digital Crate Limited | Information & communication | 2015 |
| Digitom Ltd | Information & communication | 2009 |
| Diplock Fuel Injection Services Limited | Wholesale & retail | 1985 |
| Diplocks Community Trust | Administrative & support | 2001 |
| Diplocks Ltd | Manufacturing | 2024 |
| Direct Electrical Testing Ltd | Construction | 2021 |
| Direct Law Limited | Professional & scientific | 2023 |
| Dirt Racing Ltd | Arts & recreation | 2020 |
| Dirt Store Ltd | Wholesale & retail | 2023 |
| Dirty Business Limited | Water & waste | 2015 |
| Discus Advisory Limited | Administrative & support | 2014 |
| DJH Anaesthetic Services Ltd | Health & social care | 2025 |
| Djpd Property Ltd | Real estate | 2024 |
| DK Financial Consultancy Limited | Financial services | 2015 |
| DKP Accountants Sussex Limited | Professional & scientific | 2011 |
| DLB Consulting Limited | Professional & scientific | 2006 |
| DLC Construction Sussex Limited | Construction | 2026 |
| DLG Psychology Ltd | Health & social care | 2016 |
| Dlighting Limited | Construction | 2012 |
| DLL01 Ltd | Wholesale & retail | 2017 |
| DM (Engineering) Designs Limited | Professional & scientific | 2020 |
| DM2 Property Transformations Limited | Construction | 2023 |
| DMC Groundwork Limited | Construction | 2007 |
| Dmca Developments Limited | Construction | 2017 |
| DMG Holdings (Sussex) Limited | Financial services | 2016 |
| DND Solutions Ltd | Administrative & support | 2018 |
| Docandreaday Limited | Health & social care | 2022 |
| Dockree Medical Limited | Health & social care | 2024 |
| Dog Splash Limited | Agriculture & fishing | 2024 |
| Doggy Dining Limited | Wholesale & retail | 2015 |
| Doghouse Hailsham Ltd | Hospitality | 2026 |
| Doppiog Ltd | Professional & scientific | 2022 |
| Doubledeclutch Limited | Information & communication | 2018 |
| Douessa Management Ltd | Real estate | 2024 |
| Douglas Cars Ltd | Administrative & support | 2010 |
| Douglas James Publishing Limited | Information & communication | 2023 |
| Downing (Green Gables) Limited | Health & social care | 1999 |
| Downlands Funeral Care Ltd | Other services | 2026 |
| Downs Property Care Limited | Construction | 2018 |
| DPM Design & Build Ltd | Construction | 2020 |
| DR Corina Moisoiu-Rosca Limited | Health & social care | 2020 |
| DR James Nicholson Limited | Health & social care | 2021 |
| DR JB Aesthetics Ltd | Health & social care | 2022 |
| DR JB Skin Ltd | Health & social care | 2025 |
| Draft 2 Design Limited | Professional & scientific | 2006 |
| Drake Plastic Surgery Ltd | Health & social care | 2020 |
| DRC (East Sussex) Limited | Manufacturing | 2024 |
| Dreamlike State Limited | Information & communication | 2012 |
| Dreamtime Travel Limited | Administrative & support | 1998 |
| Drive in Music Ltd | Information & communication | 2017 |
| Drivee Limited | Transport & logistics | 2022 |
| Dryer & Co. Flooring Transformations Limited | Construction | 2024 |
| Drytryin Ltd | Manufacturing | 2025 |
| DSC Metropolitan LLP | | 2011 |
| Dsouza Heartcare Limited | Health & social care | 2018 |
| Dsre Holdings Limited | Professional & scientific | 2000 |
| Dsre Services Limited | Health & social care | 2000 |
| Ducktail Digital Limited | Information & communication | 2026 |
| Durkan Group Enterprises Limited | Real estate | 2024 |
| Durkan Group Holdings Ltd | Financial services | 2024 |
| Durkan Orthodontics Limited | Health & social care | 2021 |
| DWA Fleet and Vehicle Services Ltd | Wholesale & retail | 2023 |