| Commercial Compliance Limited | Professional & scientific | 2021 |
| Commodities Direct Limited | Other services | 2018 |
| Common One Ltd | Professional & scientific | 2019 |
| Comms Alliance Limited | Professional & scientific | 2018 |
| Community Dermatology Solutions Limited | Health & social care | 2012 |
| Community of Three CIC | Wholesale & retail | 2026 |
| Community Wise | Health & social care | 2000 |
| Como Residents Company Limited | Households | 1980 |
| Company Child Care Limited | Education | 1988 |
| Company Stationers Limited | Manufacturing | 1990 |
| Compare the Merchants Limited | Extraterritorial | 2015 |
| Compass Care Consultants Ltd | Professional & scientific | 2025 |
| Compass Community Arts | Arts & recreation | 2003 |
| Compass Investment Plus Limited | Financial services | 2012 |
| Compassionate Companions Ltd | Health & social care | 2020 |
| Compio Enterprises Ltd | Administrative & support | 2018 |
| Compio Limited | Information & communication | 2013 |
| Complete Build (UK) Lettings Limited | Real estate | 2026 |
| Complete Build (UK) Ltd | Construction | 2025 |
| Complete Build Group Ltd | Construction | 2020 |
| Complete Build Holdings Ltd | Construction | 2021 |
| Complete Build Solutions Limited | Construction | 2012 |
| Complete Care Group Limited | Health & social care | 1999 |
| Complete Catering Contracts Limited | Construction | 2012 |
| Complete Financial UK Trading Limited | Financial services | 2010 |
| Complete Infrastructure Solutions Ltd | Construction | 2024 |
| Complete Property Services Sussex Ltd | Construction | 2023 |
| Compton Court (Eastbourne) Management Company Limited | Real estate | 1981 |
| Compton Lodge (Eastbourne) Limited | Households | 1982 |
| Compton Residents Management Company Limited | Households | 2000 |
| Compton Street Limited | Households | 2015 |
| Computer Plus (Eastbourne) Ltd | Other services | 1998 |
| Comrad Ltd | Information & communication | 2005 |
| Concept Beauty & Grooming Limited | Other services | 2011 |
| Concept Developers Ltd | Construction | 2015 |
| Concept Property Holdings & Investments Ltd | Real estate | 2019 |
| Conekt Ltd | Professional & scientific | 2014 |
| Confian Limited | Other services | 2012 |
| Confiance Orthopaedics Limited | Health & social care | 2023 |
| Congenial Concepts Ltd | Hospitality | 2022 |
| Connect OT & Case Management Limited | Health & social care | 2013 |
| Connectedhr Limited | Professional & scientific | 2010 |
| Connectionsukgroup Ltd | Transport & logistics | 2019 |
| Connexa Solutions Limited | Information & communication | 2024 |
| Conrad Investments Ltd | Financial services | 2020 |
| Cons & Teach Limited | Education | 2018 |
| Conscious Co-Living Ltd | Professional & scientific | 2019 |
| Conscious Engineering Design Limited | Professional & scientific | 2020 |
| Consegna Solutions Limited | Information & communication | 2018 |
| Consilium Restoration Limited | Other services | 2015 |
| Constrax Ltd | Construction | 2024 |
| Construction Calculus Limited | Professional & scientific | 2025 |
| Construction Cleaning Company Limited | Administrative & support | 2009 |
| Consultancymsb Limited | Information & communication | 2021 |
| Consulting Education Limited | Education | 2021 |
| Consulting Smile Services Limited | Health & social care | 2016 |
| Contour Imports Ltd | Wholesale & retail | 2021 |
| Contour Renovating & Contractors Limited | Construction | 1997 |
| Convatalk Consulting Limited | Information & communication | 2009 |
| Converteco Limited | Real estate | 2007 |
| Convey Enterprise Limited | Wholesale & retail | 2024 |
| COO Services Ltd | Administrative & support | 2025 |
| Cooden Building and Electrical Services Limited | Construction | 2015 |
| Cooden Diagnostics Limited | Health & social care | 2023 |
| Cool'Em Refrigeration and Air Conditioning Services Ltd | Construction | 2021 |
| Coonan & Co Limited | Hospitality | 2015 |
| Coopers Croft Management Company Limited | Households | 2023 |
| Copley Homes Ltd | Construction | 2013 |
| Copper Moth Design Ltd | Professional & scientific | 2017 |
| Copperfields Day Nursery Limited | Education | 2003 |
| Copperhouse Consultants Ltd | Wholesale & retail | 2026 |
| Copy Genie Limited | Administrative & support | 2015 |
| Copy Xpress Limited | Financial services | 1999 |
| Copylink Holdings Ltd | Wholesale & retail | 2022 |
| COR Dental Limited | Health & social care | 2023 |
| Coral Perfumes Industry UK Ltd | Manufacturing | 2023 |
| Corbett & Co Limited | Professional & scientific | 2002 |
| Core Conversations Limited | Other services | 2018 |
| CORE8 Constructions Ltd | Construction | 2024 |
| Coregtm Advisory Limited | Administrative & support | 2026 |
| Corkfox Ltd | Professional & scientific | 2025 |
| Corner Stone Installations Limited | Construction | 2025 |
| CORNER6MUSIC Limited | Arts & recreation | 2017 |
| Corners Investments Limited | Real estate | 2023 |
| Cornerstone Chiropractic Ltd | Health & social care | 2023 |
| Cornerstone Property File Limited | Households | 2025 |
| Cornerstone Structural Design Limited | Professional & scientific | 2015 |
| Cornfield Accountants Limited | Professional & scientific | 2021 |
| Cornfield Estates Limited | Real estate | 2021 |
| Cornfield Fish and Chips Ltd | Hospitality | 2025 |
| Cornhill and City Limited | Financial services | 2012 |
| Corporate & Commercial Insurance Services Limited | Financial services | 1987 |
| Corporate Presentation Limited | Information & communication | 1998 |
| Corporate Property Management Limited | Hospitality | 2024 |
| Corrie Lodge Residents Limited | Households | 1989 |
| Corro Eastbourne Limited | Wholesale & retail | 2007 |
| Corro Property Services Limited | Administrative & support | 2024 |
| Corvus Investments Limited | Other services | 2010 |
| Cosgrove Refurbishments Ltd | Construction | 2026 |
| Cosmos Motor Trading Limited | Wholesale & retail | 2021 |