| Clarence Construction Limited | Construction | 2004 |
| Classiq Limited | Professional & scientific | 2007 |
| Claxton Laundry Limited | Real estate | 1918 |
| CLC Sussex 2 Ltd | Wholesale & retail | 2021 |
| Clear Screen Solutions Limited | Information & communication | 2003 |
| Clever Project Solutions Ltd. | Information & communication | 2005 |
| Clickcover Limited | Financial services | 2007 |
| Clinical Computer Systems Limited | Administrative & support | 2005 |
| Clive Voller Associates Limited | Professional & scientific | 2003 |
| CMH Lancing Limited | Construction | 2007 |
| CML Tamworth LP | | 2002 |
| Coach Educate Ltd | Education | 2015 |
| Coastal Developments (Southern) Limited | Real estate | 2007 |
| Coles Refrigeration Limited | Construction | 2004 |
| Commercial Property Associates Limited | Real estate | 2002 |
| Complete Garden Care Limited | Other services | 2026 |
| Connecting Solutions Limited | Information & communication | 2005 |
| Connolly INK LLP | | 2024 |
| Consort Confectionery Limited | Wholesale & retail | 1997 |
| Consort Frozen Foods Limited | Wholesale & retail | 1986 |
| Constructive Projects Ltd | Information & communication | 2007 |
| Copthorne Kinders Limited | Education | 2006 |
| Corporate Resources South Ltd | Professional & scientific | 2005 |
| Cottonwood Consulting Limited | Professional & scientific | 2005 |
| County Windows and Conservatories Limited | Construction | 1990 |
| Cover-Up Interiors Limited | Wholesale & retail | 1988 |
| Craig M. Whitsey (Gunmakers) Limited | Manufacturing | 1969 |
| Craigdaragh Properties Limited | Hospitality | 1995 |
| Cranborne Interiors Limited | Construction | 2002 |
| Crawley Spice Ltd | Hospitality | 2024 |
| Crawley Car Company Ltd | Transport & logistics | 2005 |
| Crawley Flooring Limited | Professional & scientific | 1985 |
| Crawley Hotel Limited | Hospitality | 2000 |
| Crawley Property Services Limited | | 2010 |
| Creations Hair Salon (UK) Limited | Real estate | 2002 |
| Creative Thinking in Manufacturing Limited | Professional & scientific | 2005 |
| Crescentworth Limited | Health & social care | 1977 |
| Crestneat Limited | Wholesale & retail | 1990 |
| Crimson King Ltd | Professional & scientific | 2002 |
| Croftscope Limited | Other services | 1997 |
| Crops & Bobbers Redhill Limited | Other services | 2002 |
| Croucher Property Maintenance Limited | | 1987 |
| Cruxton Estates Limited | Real estate | 1971 |
| Cuckfield Cake Shop Limited | Wholesale & retail | 2007 |
| Culibra Health Limited | Wholesale & retail | 2006 |
| Culver Cars Limited | Wholesale & retail | 2003 |
| Custom Computer Systems Ltd. | Information & communication | 1995 |
| Customerking Limited | Other services | 1995 |
| D & a Real Estate Limited | Real estate | 2005 |
| D Faulkner Limited | Extraterritorial | 1999 |
| D Faulkner Springs LLP | | 2006 |
| D. G. K. Carpets Limited | | 1976 |
| D. H. Grounds Maintenance Limited | Construction | 2005 |
| D.G. Pool & Leisure Limited | Construction | 2006 |
| D.J. Redman Limited | Wholesale & retail | 1997 |
| D.W. Controls Limited | Professional & scientific | 1994 |
| DA Conti International Limited | Professional & scientific | 1986 |
| DAN Bush Ltd | Administrative & support | 2006 |
| Danentec Limited | Information & communication | 2006 |
| Dansam Developments Limited | Manufacturing | 1987 |
| Dash Investments Limited | Real estate | 2003 |
| Data Analytics Consulting Ltd | Information & communication | 2024 |
| Dave Silver Editing Ltd | Professional & scientific | 2024 |
| David Cooper Racing Limited | Arts & recreation | 2015 |
| David Foreman Carpets Limited | Wholesale & retail | 2003 |
| Davies Business Properties Ltd | Real estate | 2021 |
| Davlin Developments Limited | Real estate | 2002 |
| Dclh Engineering Ltd | Construction | 2022 |
| DDE (SW) Limited | Construction | 2004 |
| Deen Management Limited | Professional & scientific | 1996 |
| Deep Green Landscaping Limited | Administrative & support | 2006 |
| Dellner Ferrabyrne Holdings Limited | Professional & scientific | 2016 |
| Dellner Ferrabyrne Limited | Manufacturing | 1970 |
| Deltex Medical Limited | Manufacturing | 1983 |
| Denne Meadow Construction Limited | Construction | 2025 |
| Dependable Care & Services Limited | Health & social care | 2017 |
| Design Directive Limited | Construction | 2010 |
| Destination Makers Limited | Professional & scientific | 2002 |
| Developing Database Solutions Ltd | Information & communication | 2007 |
| Diagonal Trees Limited | Professional & scientific | 2025 |
| Digiworks Consulting Limited | Information & communication | 2007 |
| Direct Wholesale Foods (London) Limited | Wholesale & retail | 1972 |
| DMD Plant Limited | Construction | 2006 |
| Dolphin Glassfibre Limited | Manufacturing | 1975 |
| Dominion Windows Ltd | Wholesale & retail | 2005 |
| Dorking Window Company Limited | Construction | 2005 |
| Dove Routing Limited | Water & waste | 1988 |
| Downsbrook Park (Hassocks) Management Limited | Households | 1989 |
| Downview Developments Limited | Construction | 1999 |
| Drainaid Services Ltd | Water & waste | 2026 |
| DRE (SE) Limited | Extraterritorial | 2003 |
| Drecu Sussex Ltd | Manufacturing | 2024 |
| Driftwood Solutions Ltd | Administrative & support | 2007 |
| Drummond Investments Limited | Professional & scientific | 1997 |
| DSB Garden Services Limited | Administrative & support | 2007 |
| Dualit Limited | Manufacturing | 1948 |
| Dukes Motors Limited | Administrative & support | 2002 |
| Dukes Valley LLP | | 2003 |
| Durana Limited | Construction | 1972 |
| Durno Launderettes Limited | Other services | 1973 |