| CT Business Consulting Limited | Professional & scientific | 2013 |
| CTD Management Ltd | Households | 2025 |
| CTP Developments Limited | Real estate | 2014 |
| CTS Property Management Ltd | Hospitality | 2021 |
| Cuddledry Limited | Wholesale & retail | 2006 |
| Cuff Consulting Ltd | Professional & scientific | 2022 |
| Culver Energy Consulting Limited | Professional & scientific | 2018 |
| Cunliffe Close Residents Association Ltd | Households | 2019 |
| CURAT3D Ltd | Professional & scientific | 2025 |
| Curlew Productions Limited | Arts & recreation | 2017 |
| Curran Legal Services Limited | Public administration | 2025 |
| Curtains and Blinds 02 Limited | Wholesale & retail | 2022 |
| Curtis Leeves Technical Ltd. | Professional & scientific | 2013 |
| Custom Vehicle Works Limited | Wholesale & retail | 2022 |
| Customer Transformations Limited | Information & communication | 2015 |
| Customs Management Limited | Transport & logistics | 2021 |
| CUT Carbon Ltd | Construction | 2021 |
| Cute Nooks Ltd | Hospitality | 2021 |
| Cutting Edge Carpentry & Construction Ltd | Manufacturing | 2016 |
| Cvet Limited | Professional & scientific | 2018 |
| CW Security Management Ltd | Administrative & support | 2024 |
| CWH Electrical Services Ltd | Administrative & support | 2015 |
| Cyan Star Limited | Administrative & support | 2020 |
| Cyanne Ltd | Professional & scientific | 2025 |
| Cycle Innovation Limited | Wholesale & retail | 2014 |
| Cycletime Limited | Mining & quarrying | 2001 |
| D & a Watkins Ltd | Professional & scientific | 2022 |
| D & E Homes of Sussex Ltd | Construction | 2019 |
| D & J Plumbing Supplies Ltd | Wholesale & retail | 2012 |
| D & M Builders Sussex Limited | Construction | 2014 |
| D Adams & Sons Roofing Limited | Construction | 1997 |
| D Alan Construction Ltd | Real estate | 2014 |
| D and M Communications Limited | Hospitality | 1994 |
| D B Associates (2010) Limited | Professional & scientific | 2010 |
| D Cowan Domestic Plumbing & Heating Limited | Construction | 2013 |
| D Good Flooring Ltd | Construction | 2020 |
| D Hanna Ltd | Health & social care | 2022 |
| D W Electrical Contractors Limited | Construction | 2017 |
| D W Plastics Group Ltd | Manufacturing | 2016 |
| D&L Solutions Ltd | Wholesale & retail | 2025 |
| D&S Ventures Limited | Real estate | 2020 |
| D.A. Safety Critical Services Ltd. | Manufacturing | 2014 |
| D.I. Supplies Ltd | Wholesale & retail | 2002 |
| D.K. Majo Developments Ltd | Real estate | 2023 |
| D.K. Majo Estates Limited | Real estate | 1996 |
| D.K. Majo Holdings Ltd | Financial services | 2023 |
| D.W. NYE Limited | Wholesale & retail | 1984 |
| D.W. Plastics Limited | Manufacturing | 1980 |
| D3R Ltd | Information & communication | 2006 |
| D3R Trustees Limited | Professional & scientific | 2024 |
| D4 Property Services Ltd | Construction | 2026 |
| Dacary Ltd | Professional & scientific | 2024 |
| Dach FMS Ltd | Wholesale & retail | 2020 |
| Dacrs Property Consultancy Limited | Real estate | 2013 |
| Dacrs Property Limited | Real estate | 2012 |
| Dailyme Ltd | Information & communication | 2025 |
| Daisy Lawson Ltd | Real estate | 2018 |
| Dale Ellis Properties Ltd | Real estate | 2020 |
| Dale Sheppard Designs Limited | Construction | 2001 |
| Daley Consulting Ltd | Extraterritorial | 2014 |
| Dalsan West Estates Limited | Financial services | 2022 |
| Daly & Lyon Ltd | Professional & scientific | 2017 |
| Dame School Court Residents Association Limited | Households | 1987 |
| DAN Pepall Property Sourcing Ltd | Real estate | 2024 |
| Danforth Holdings Limited | Real estate | 2025 |
| Dangstein Farm Ltd | Agriculture & fishing | 2022 |
| Danscof Investments | Financial services | 2014 |
| Darkbridge Partners Ltd | Information & communication | 2024 |
| Darren Magri Limited | Construction | 2008 |
| Dart Facility Services (CM) Ltd | Construction | 2016 |
| Darwazakam Ltd | Other services | 2025 |
| Data 2 Patterns and Moulds Limited | Manufacturing | 2002 |
| Data Bay Computing Limited | Information & communication | 1991 |
| DAU Electronics Limited | Manufacturing | 2012 |
| Daveh Consulting Limited | Professional & scientific | 2016 |
| Daves Coils Limited | Extraterritorial | 2024 |
| David Allan Consulting Ltd | Information & communication | 2023 |
| David Cover and SON Limited | Manufacturing | 1945 |
| David Harriott Limited | Agriculture & fishing | 2014 |
| David Hoare Limited | Construction | 1971 |
| David Leslie Ltd | Administrative & support | 2022 |
| David Simon Trading Limited | Wholesale & retail | 2020 |
| David Winter Independent Financial Advisers Limited | Financial services | 2007 |
| Davisian Limited | Professional & scientific | 2013 |
| Davles Ltd | Financial services | 2024 |
| Dawson Court Residents' Association Limited | Households | 1972 |
| Dayside Ltd | Wholesale & retail | 2021 |
| DB Scaffolding (Sussex) Limited | Construction | 2024 |
| DBA Medical UK Limited | Health & social care | 2009 |
| Dbak Consulting Limited | Professional & scientific | 2025 |
| DC 78 Ltd | Financial services | 2022 |
| DC Offsite Limited | Construction | 2026 |
| Dcestore Ltd | Wholesale & retail | 2026 |
| DCP Autos Ltd | Wholesale & retail | 2024 |
| DDA Accountancy Limited | Professional & scientific | 2016 |
| DDB International Limited | Information & communication | 2023 |
| DE Burgh Holding Ltd | Professional & scientific | 2018 |
| DE Burgh London Limited | Extraterritorial | 2011 |
| DE Burgh Training Limited | Professional & scientific | 2011 |
| DE Cestre Consulting Ltd | Professional & scientific | 2026 |