| Craft Roastery Ltd | Hospitality | 2022 |
| Crank Fabrications Ltd | Manufacturing | 2020 |
| Cranwell Wealth Solutions Limited | Administrative & support | 2014 |
| Cratur Holdings Ltd | Real estate | 2013 |
| Crealit Ltd | Wholesale & retail | 2023 |
| Crest Hawk Investigations Ltd | Administrative & support | 2018 |
| Crofts Holdings Limited | Real estate | 2016 |
| Cropax Ltd | Wholesale & retail | 2024 |
| Crosthwaite and Gardiner Limited | Manufacturing | 1991 |
| Crowborough Beacon Lodge Trustee Company Limited | Other services | 2014 |
| Crowborough Foundation | Education | 2009 |
| Croydon Photographic Company Limited(The) | Real estate | 1949 |
| Crusader Vehicles Limited | Wholesale & retail | 2007 |
| Crystal Vision Windows Ltd | Construction | 2005 |
| CS ET Alia Limited | Professional & scientific | 2025 |
| CTR Learning CIC | Education | 2023 |
| Cube Records Management Services Limited | Professional & scientific | 2008 |
| Cube Self Storage Angmering Ltd | Transport & logistics | 2026 |
| Cube Self Storage Limited | Real estate | 2002 |
| Culleton Electrical Contractors Ltd | Construction | 2015 |
| Custom Carpentry Sussex Limited | Manufacturing | 2022 |
| Customer Thermometer Technology Limited | Information & communication | 2025 |
| CV Cyclone Ltd | Administrative & support | 2012 |
| D Leonard & Co Limited | Manufacturing | 2004 |
| D Thorogood Building & Roofing Ltd | Construction | 2019 |
| D&D Car Ltd | Wholesale & retail | 2026 |
| D. T. Williams Limited | Wholesale & retail | 1980 |
| D.P Groundworks and Landscaping Limited | Administrative & support | 2025 |
| D1SRUPT Digital Ltd | Professional & scientific | 2025 |
| D8 Group Limited | Professional & scientific | 2022 |
| D8 Holdings Limited | Real estate | 2024 |
| DA Clark Groundworks Ltd | Construction | 2021 |
| Dapper FOX Property Ltd | Professional & scientific | 2021 |
| Darlington-Turnbull-Productions Limited | Other services | 2019 |
| Dash MVS Limited | Wholesale & retail | 2025 |
| Datagraphics Limited | Extraterritorial | 1984 |
| Dave’S Domestic Household Agency Ltd | Administrative & support | 2026 |
| David Carr Coordinator Ltd | Professional & scientific | 2017 |
| David Gray Limited | Professional & scientific | 2023 |
| Dawa Inc Ltd | Professional & scientific | 2015 |
| Dawlon Limited | Information & communication | 2010 |
| Dawson Hart Solicitors Limited | Professional & scientific | 2012 |
| Daybreak Music Limited | Information & communication | 1979 |
| Dayset Ltd | Hospitality | 2026 |
| DDT Building and Construction Ltd | Construction | 2025 |
| Deakin Oak Limited | Agriculture & fishing | 1999 |
| Debra Clare Limited | Manufacturing | 2006 |
| Deerbrook Dunstall Avenue Limited | Households | 2010 |
| Delarc IT Ltd | Information & communication | 2006 |
| Delisce Limited | Construction | 2002 |
| Deliwell Ltd | Wholesale & retail | 2015 |
| Dembell Limited | Financial services | 2012 |
| Dernwood Consulting Ltd | Information & communication | 2023 |
| Design & Display Structures Limited | Manufacturing | 2003 |
| Design Goose Limited | Arts & recreation | 2003 |
| DG CNC Services Limited | Manufacturing | 2016 |
| Dialog Partners Ltd | Health & social care | 2016 |
| Digital Enterprise 2020 Ltd | Information & communication | 2020 |
| Digital Health Systems Ltd | Information & communication | 2023 |
| Directory of Homeopaths Limited | Other services | 2007 |
| Direwolf Consultancy Limited | Professional & scientific | 2025 |
| DJ Brickwork General Builders Limited | Construction | 2024 |
| DJC Heating Solutions Limited | Construction | 2021 |
| DJD Law Limited | Professional & scientific | 2018 |
| DL Southern Ltd | Administrative & support | 2011 |
| Domarn Limited | Professional & scientific | 1988 |
| Domenauk Ltd | Wholesale & retail | 2025 |
| Domonkos Holding Ltd | Financial services | 2022 |
| DOORS4DIY Limited | Wholesale & retail | 2025 |
| Dove Court (Uckfield) Limited | Real estate | 1991 |
| Dovell Ltd | Administrative & support | 2019 |
| Dower House Farms Ltd | Agriculture & fishing | 2023 |
| Dowgate Associates Ltd | Information & communication | 2026 |
| Downlands Design & Surveying Limited | Professional & scientific | 2014 |
| DP & RH Properties Limited | Real estate | 2025 |
| DQA Ltd | Manufacturing | 2019 |
| DR Life Ltd | Health & social care | 2018 |
| DRJ Events Ltd | Arts & recreation | 2020 |
| DSD Concrete Ltd | Construction | 2016 |
| Dudas-It Ltd | Information & communication | 2012 |
| Duke Letting Limited | Real estate | 2018 |
| Duke Management Limited | Real estate | 2005 |
| Duna Limited | Construction | 2015 |
| Duradiamond Health Partners Limited | Health & social care | 2016 |
| Dynamic Lifts Ltd | Construction | 2025 |
| Dysrupt Ltd | Information & communication | 2022 |
| E & M Plumbing & Heating Limited | Construction | 2022 |
| E & M Plumbing & Pipe Fitting Services Limited | Construction | 2007 |
| E G Hockey Academy LLP | | 2011 |
| E H B Holdings Limited | Administrative & support | 2024 |
| E.E. Houlton (Westminster) Limited | Hospitality | 1961 |
| E.S.I.C. Ltd | Energy | 2017 |
| E4ENABLE Ltd | Information & communication | 2018 |
| Each Way Solutions Ltd | Professional & scientific | 2024 |
| Eagle Alliance Limited | Financial services | 2004 |
| Eagle Talent Partners Ltd | Professional & scientific | 2020 |
| Earnonline Services Ltd | Wholesale & retail | 2024 |
| East Hoathly and Halland Carnival Society Limited | Other services | 1997 |
| East Sussex Flooring Ltd | Construction | 2024 |
| East Sussex Press Limited | Manufacturing | 1993 |