| Cielo Cakery Limited | Wholesale & retail | 2018 |
| Cielo Coffee House Ltd | Manufacturing | 2025 |
| Cimerian Ltd | Information & communication | 2026 |
| Cimmix Ltd | Information & communication | 2008 |
| CIN CIN (UK) Limited | Hospitality | 2013 |
| Cinda & Co Limited | Information & communication | 2020 |
| Cine Hire Ltd | Administrative & support | 2026 |
| Cinemagear Leasing Limited | Administrative & support | 2025 |
| Cinemation Limited | Information & communication | 2023 |
| Cinenergy Ltd | Administrative & support | 2019 |
| Cineplan Ltd | Extraterritorial | 2025 |
| Cinnamon JAM Ltd | Information & communication | 2010 |
| CIO Electrical Ltd | Construction | 2022 |
| Circa 69 Limited | Information & communication | 2010 |
| Circular Inc. Ltd | Manufacturing | 2020 |
| Circuteq Ltd | Wholesale & retail | 2024 |
| Cisco Corporation Ltd | Professional & scientific | 2019 |
| Ciscos Karma Ltd | Other services | 2026 |
| Cissbury Enterprises Ltd | Other services | 2000 |
| City & Manor Cleaning Services Ltd | Administrative & support | 2026 |
| City & Sea Property Ltd | Real estate | 2019 |
| City Artisans Ltd | Construction | 2019 |
| City Bespoke Ltd | Construction | 2023 |
| City Bough Limited | Information & communication | 2025 |
| City Building Services Limited | Construction | 2001 |
| City Cabs (Brighton) Limited | Transport & logistics | 1996 |
| City Concepts Ltd | Construction | 2015 |
| City Fire Risk Assessments Limited | Professional & scientific | 2000 |
| City Food Share CIC | Health & social care | 2019 |
| City Gate Church, U.K. | Other services | 2001 |
| City Gate Community Projects | Administrative & support | 2001 |
| City Gateway Development Limited | Construction | 2002 |
| City Girl Network Limited | Information & communication | 2017 |
| City House Investments Limited | Real estate | 2021 |
| City IT PM Ltd | Information & communication | 2014 |
| City Lofts Management (Argus Building) Limited | Households | 2001 |
| City Nestled Limited | Professional & scientific | 2025 |
| City Partnership Housing Ltd | Administrative & support | 2013 |
| City Products Limited | Wholesale & retail | 2017 |
| City Spot Ltd | Real estate | 2023 |
| City Streamline Limited | Extraterritorial | 2007 |
| Citypro Associates Limited | Professional & scientific | 2021 |
| Citywide Lofts Ltd | Construction | 2023 |
| Cityzen Limited | Professional & scientific | 2017 |
| Civil Celebrant Connection Ltd | Education | 2025 |
| Civil Design & Draughting Limited | Professional & scientific | 1997 |
| Civil Preparedness Ltd | Professional & scientific | 2023 |
| Civil Service Motoring Association,Limited(The) | Other services | 1930 |
| CJ Accountancy & Bookkeeping Limited | Professional & scientific | 2015 |
| CJ Recuits Global Limited | Professional & scientific | 2024 |
| CJB Search Limited | Administrative & support | 2019 |
| CJC Partnership Limited | Real estate | 2016 |
| Cjlsg Ltd | Wholesale & retail | 2026 |
| Cjse Properties Limited | Real estate | 2021 |
| CK (Holdings Company) Ltd | Other services | 2020 |
| CK Better Future C.I.C. | Health & social care | 2026 |
| CK Bistro Brighton Ltd | Hospitality | 2022 |
| CK Bits Ltd | Information & communication | 2009 |
| Ckmk Limited | Arts & recreation | 2006 |
| Clabel Limited | Information & communication | 2016 |
| Claims Recovery Group Ltd | Financial services | 2025 |
| Claimscog Limited | Financial services | 2020 |
| Claire Byrd Communications Ltd | Professional & scientific | 2011 |
| Claire Lipscomb Mortgages Ltd | Financial services | 2023 |
| Claire Thomas Media Ltd | Information & communication | 2022 |
| Claire Whyley Consulting Limited | Professional & scientific | 2024 |
| Clampets Ltd | Real estate | 1999 |
| Clan Mechanical Services Ltd | Construction | 2020 |
| Clank Limited | Hospitality | 2014 |
| Clapham Holdings Limited | Financial services | 2016 |
| Clappers House Estates Limited | Real estate | 2009 |
| Clare Trent Designs Ltd | Professional & scientific | 2025 |
| Claremont Residents Association Limited | Households | 1996 |
| Clarence RTM Company Limited | Households | 2017 |
| Clarence Square (Brighton) Freehold Limited | Households | 2019 |
| Clarendon Place RTM Company Limited | Households | 2019 |
| Clarendon Villas Limited | Construction | 2019 |
| Claret Star Consulting Ltd | Professional & scientific | 2016 |
| Claridad Limited | Construction | 2017 |
| Clarity & Ltd | Professional & scientific | 2022 |
| Clarity Carbon Limited | Professional & scientific | 2009 |
| Clarity Climate Solutions Limited | Professional & scientific | 2024 |
| Clarity Environmental Limited | Water & waste | 2002 |
| Clarity Recruitment Solutions Ltd | Administrative & support | 2007 |
| Clark & James Limited | Construction | 2003 |
| Clark and Blue Enterprises Limited | Real estate | 2012 |
| Clark Ceilings Ltd | Extraterritorial | 2015 |
| Clark French Limited | Professional & scientific | 2022 |
| Clark Strategic Ltd | Professional & scientific | 2024 |
| Clark's Meat & Poultry Ltd | Wholesale & retail | 2011 |
| Clarke Alexander Limited | Professional & scientific | 2018 |
| Clarke Associates (GB) Ltd | Professional & scientific | 2003 |
| Clarke Foods Limited | Wholesale & retail | 2015 |
| Clarke Goodhand Smith Limited | Professional & scientific | 2018 |
| Clarke-Walker Financial Management Limited | Financial services | 2006 |
| Clarkes of Brighton Limited | Construction | 2016 |
| Claromentis Limited | Information & communication | 1998 |
| Clash Digital Limited | Professional & scientific | 2016 |
| Clash Motion Ltd | Other services | 2019 |
| Class 1 Welding Ltd | Construction | 2016 |