| Clayson Group Limited | Construction | 2012 |
| Clayspoon Limited | Manufacturing | 2016 |
| Claystone Builders Ltd | Construction | 2015 |
| Clayton Build Ltd | Construction | 2026 |
| CLC Consulting Ltd | Professional & scientific | 2025 |
| Clean Corner Choice Limited | Administrative & support | 2024 |
| Clean Corner Limited | Administrative & support | 2018 |
| Clean Corner Maintenance and Lettings Ltd | Other services | 2021 |
| Clear Aligner Ltd | Wholesale & retail | 2024 |
| Clear MOT Eastbourne Ltd | Wholesale & retail | 2025 |
| Clear Path Contracting Ltd | Construction | 2026 |
| Clear View (Sussex) Limited | Manufacturing | 2002 |
| Clearance Bargains Online Ltd | Wholesale & retail | 2025 |
| Clearflow Treasury Ltd | Professional & scientific | 2026 |
| Clearforcegroup Ltd | Administrative & support | 2026 |
| Cleverledger Ltd | Information & communication | 2026 |
| Cliff House Tenants Association Limited | Households | 1975 |
| Cliffe Enterprise Holdings Limited | Financial services | 2017 |
| Cliffe Enterprise Limited | Manufacturing | 2014 |
| Clifford Osborne Limited | Professional & scientific | 2013 |
| Clifford Osborne Wealth Management Ltd | Extraterritorial | 2019 |
| Clifton Court (Eastbourne) Limited | Households | 2008 |
| Clifton House Upper Avenue Limited | Extraterritorial | 2004 |
| Climate Funding Bridge Ltd | Professional & scientific | 2024 |
| Clinipaw Ltd | Other services | 2024 |
| Clinton Development Company Limited | Other services | 1998 |
| CLK Resource (GmbH) Limited | Professional & scientific | 2016 |
| Clockhouse Court Residents Association Limited | Households | 1970 |
| Cloona East (Eastbourne) Ltd | Households | 2025 |
| Close-Up Film Centre Limited | Information & communication | 2005 |
| Cloud Nine Playtime Limited | Arts & recreation | 2025 |
| Cloudconnx Limited | Information & communication | 2011 |
| Cloudwalk Ltd | Health & social care | 2013 |
| Cloudy Window Fixer Ltd | Construction | 2021 |
| Clover Cottage (Management) Limited | Households | 2002 |
| Clover House Dental Practice Sleaford Limited | Health & social care | 2011 |
| Clrc Property Holdings Limited | Real estate | 2019 |
| Club 4 Travel Ltd | Administrative & support | 2014 |
| Club Belts Limited | Wholesale & retail | 2020 |
| Club Class Coaches Limited | Transport & logistics | 2003 |
| Clubhouse Incorporated Limited | Construction | 2015 |
| Clubhouse Interiors Limited | Wholesale & retail | 2011 |
| Clyde Balmoral Investment Group Limited | Real estate | 2024 |
| CM Financial Solutions Ltd | Professional & scientific | 2025 |
| CMT Construction Limited | Other services | 2018 |
| Co Property Partners Ltd | Real estate | 2026 |
| Co-Living Accommodation Ltd | Hospitality | 2019 |
| Co-Narrate Limited | Professional & scientific | 2023 |
| Coach House Dental Practice Limited | Health & social care | 2006 |
| Coach Lockey Ltd | Information & communication | 2025 |
| Coachbelgrave Limited | Education | 2025 |
| Coachedbyhbn Ltd | Health & social care | 2024 |
| Coaching Shore Limited | Other services | 2012 |
| Coalition Consulting International Limited | Professional & scientific | 2009 |
| Coast Veterinary Referrals Limited | Professional & scientific | 2011 |
| Coastal Crest Developments Ltd | Real estate | 2025 |
| Coastal Glass Ltd | Construction | 2024 |
| Coastal Investments (S.E.) Limited | Real estate | 1995 |
| Coastal Mechanical Services Ltd | Construction | 2021 |
| Coastal Property Management Limited | Real estate | 2016 |
| Coastline Consulting Limited | Professional & scientific | 2026 |
| Coastline Financial Ltd | Financial services | 2021 |
| Coastline Poster Services Limited | Professional & scientific | 1985 |
| Coastprop Trade Ltd | Construction | 2015 |
| Coastway Commercial Limited | Financial services | 2023 |
| Coastway Sussex Limited | Financial services | 2021 |
| COB Dent Limited | Health & social care | 2025 |
| Cobbold 1952 Limited | Extraterritorial | 2013 |
| Cobia Lettings Limited | Real estate | 2018 |
| Cocobee Nail Bar Limited | Other services | 2020 |
| Code Red Digital Ltd | Information & communication | 2020 |
| Coffee & Carrot Limited | Hospitality | 2024 |
| Coffee Drops Eastbourne Ltd | Hospitality | 2022 |
| Cognitive and Political Systems Limited | Information & communication | 2000 |
| Cognitive Dissonance Limited | Other services | 2013 |
| Coker and Clarke Limited | Wholesale & retail | 2024 |
| Colby Property Investments Ltd | Financial services | 2022 |
| Coldwired Games Ltd | Information & communication | 2010 |
| Cole Moreton Ltd | Arts & recreation | 2017 |
| Cole's Estate Agents Limited | Real estate | 2009 |
| Colin and Gavin Humphrey Architects Limited | Professional & scientific | 2021 |
| Colin Daniels Limited | Wholesale & retail | 2009 |
| COLLABORATE2 Ltd | Information & communication | 2021 |
| Collagen Health Ltd | Wholesale & retail | 2025 |
| College Court (Eastbourne) Management Company Limited | Hospitality | 2015 |
| College of Practitioners of Phytotherapy | Health & social care | 1993 |
| Collier Homes Ltd | Construction | 2019 |
| Collier Webb Limited | Manufacturing | 2000 |
| Collington (Tudor Court) Limited | Households | 1968 |
| Colmor Consulting Ltd | Professional & scientific | 2016 |
| Colorville Ltd | Manufacturing | 2022 |
| Colour Consultant Service Limited | Wholesale & retail | 1965 |
| Colour Gamut UK Limited | Administrative & support | 2023 |
| Colour Supplies (2024) Limited | Financial services | 2024 |
| Colour Supplies (Chesham) Limited | Wholesale & retail | 1982 |
| Colston Limited | Administrative & support | 2005 |
| Columbus Point (Management Company) Limited | Households | 2001 |
| Colwood Commercial Property Services Ltd | Water & waste | 2017 |
| Combe 90 Engineering Ltd | Manufacturing | 2024 |
| Comel Export Services Ltd. | Financial services | 1955 |