| Countywide Roofing Limited | Construction | 2015 |
| COX Marine Limited | Professional & scientific | 2014 |
| COX Powertrain Holdings Limited | Extraterritorial | 2019 |
| COX Powertrain Limited | Manufacturing | 2005 |
| Create 51 Ltd | Professional & scientific | 2014 |
| Create-Ai Limited | Information & communication | 2024 |
| Creds Music Ltd | Information & communication | 2021 |
| Croft (Southwick) Residents Association Limited(The) | Households | 1973 |
| Crosbygower Ltd | Real estate | 2018 |
| Crown Research Ltd | Administrative & support | 2010 |
| Crystal Clean Sussex Ltd | Administrative & support | 2026 |
| Crystal Supplements Limited | Administrative & support | 2010 |
| CS Automation Limited | Manufacturing | 2009 |
| Curbside Limited | Extraterritorial | 2023 |
| Curbside Waste & Recycling Limited | Professional & scientific | 2018 |
| Curio Trading Ltd | Wholesale & retail | 2022 |
| Curio Wine & Spirits Ltd | Wholesale & retail | 2023 |
| Current Beauty Ltd | Other services | 2017 |
| CVL Rentals Limited | Wholesale & retail | 2013 |
| CWL Management Company Limited | Households | 2020 |
| CWN Digital Publishing Ltd | Information & communication | 2017 |
| CX Plumbing & Heating Ltd | Households | 2026 |
| D L Collins Limited | Construction | 2021 |
| D&S Automotive Group Ltd | Wholesale & retail | 2025 |
| D.C.Geoghegan Limited | Construction | 2005 |
| D.P.A Penwarden Limited | Professional & scientific | 2024 |
| Daina Systems Limited | Information & communication | 2011 |
| DAK Consultants Limited | Professional & scientific | 2011 |
| Daley Investments Ltd | Real estate | 2024 |
| Datasharp UK Limited | Manufacturing | 1984 |
| David Calderbank Consulting Ltd | Professional & scientific | 2020 |
| David Gaywood Media Limited | Arts & recreation | 2012 |
| David Meredith Translations Ltd | Professional & scientific | 2013 |
| David Murphy Holdings Ltd | Financial services | 2024 |
| David Murphy Ltd | Education | 2023 |
| David Tobin Energy and Carbon Consulting Limited | Professional & scientific | 2023 |
| Deacons Property and Investments Limited | Real estate | 2011 |
| Dean Fraser & Sons Ltd | Extraterritorial | 2013 |
| Definitive Projects Limited | Information & communication | 2015 |
| Delft Housing Limited | Real estate | 2016 |
| Dempsey Construction & Management Ltd | Construction | 2019 |
| Denman Brace Financial Management Limited | Financial services | 2006 |
| Dennis Watkins & Company Limited | Financial services | 1969 |
| Dennis Watkins Group Limited | Professional & scientific | 1957 |
| Dept Limited | Wholesale & retail | 2016 |
| Desikhana Ltd | Hospitality | 2020 |
| Development Garden Ltd | Professional & scientific | 2008 |
| Devlan Decor Ltd | Construction | 2019 |
| DGA Complete Construction Ltd | Construction | 2011 |
| DIG & Design Construction Limited | Construction | 2025 |
| Digi Vape Ltd | Wholesale & retail | 2019 |
| Digitas Group Limited | Professional & scientific | 2020 |
| Diolab Solutions Ltd | Construction | 2025 |
| Dirty MAC Ltd | Hospitality | 2018 |
| Disfigured Ltd | Wholesale & retail | 2014 |
| Diva Signs Ltd | Manufacturing | 2003 |
| DJ Ksevents Ltd | Hospitality | 2025 |
| Dlux Nails Studio Ltd | Other services | 2025 |
| Dogfish Design Limited | Professional & scientific | 2021 |
| Dolphin Fitness Limited | Information & communication | 2001 |
| Doorentry.Net Limited | Administrative & support | 2005 |
| Doria Lopalco Design Limited | Administrative & support | 2025 |
| DP Mace Limited | Health & social care | 2024 |
| DPE Marketing Ltd | Administrative & support | 2015 |
| DR. Meyer-Dulheuer & Partners LLP | | 2011 |
| Draftcad Ltd | Professional & scientific | 2018 |
| Dragon Driving Limited | Professional & scientific | 2024 |
| Draper Residential Limited | Real estate | 2026 |
| Drift Shoreham Limited | Hospitality | 2021 |
| Dripdry Limited | Construction | 2020 |
| Drnk Coffee House Ltd | Hospitality | 2022 |
| Dskonsult Limited | Information & communication | 2022 |
| DTS Electrical Ltd | Construction | 2016 |
| Dual Track Ltd | Arts & recreation | 2025 |
| Dudsmore Limited | Wholesale & retail | 2022 |
| DVH Travel Group Ltd | Transport & logistics | 2020 |
| Dynamometer World Limited | Professional & scientific | 2004 |
| E K E Equipment Limited | Wholesale & retail | 2014 |
| E-English Limited | Education | 2009 |
| E2S-WELDING Ltd | Wholesale & retail | 2010 |
| Earthturner Holdings Ltd | Financial services | 2016 |
| Earthturner Ltd | Information & communication | 2016 |
| Eastern AH Limited | Wholesale & retail | 2022 |
| Eastern AP UK Ltd | Professional & scientific | 2025 |
| Eaton Gate (Management) Limited | Households | 1995 |
| Eazy Home 1 Ltd | Real estate | 2026 |
| Eazy Parcel Ltd | Transport & logistics | 2024 |
| Ebrix Investments Ltd | Real estate | 2025 |
| Eclipse (Midco 1) Limited | Financial services | 2020 |
| Eclipse (Midco 2) Limited | Financial services | 2020 |
| Eco Boiler & Renewable's Limited | Construction | 2022 |
| Ecotecture Developments Limited | Real estate | 2009 |
| Ecotecture Ecological Design Limited | Professional & scientific | 2017 |
| Eden Aviation Services Limited | Administrative & support | 1999 |
| Edward House (Hove) Limited | Households | 2000 |
| Eesy Clean Ltd | Administrative & support | 2019 |
| Elbocone Ltd | Manufacturing | 2023 |
| Electri-Tech Systems Limited | Construction | 2022 |
| Electric Farm Limited | Information & communication | 2002 |
| Electromagnetic Testing Services Limited | Professional & scientific | 1992 |