| Circle Property Assessments Limited | Real estate | 2024 |
| Circuits Integrated U.K. Ltd | Manufacturing | 2025 |
| Citieu Consultancy Ltd. | Information & communication | 2009 |
| Citiline Limited | Administrative & support | 2023 |
| Citizen Canine Limited | Other services | 2023 |
| Citrovo Ltd | Wholesale & retail | 2022 |
| Citrus Employers Oversight Company Limited | Financial services | 2023 |
| Citvest Limited | Financial services | 2023 |
| City & Merchant Limited | Financial services | 1992 |
| City Arms Oxford Limited | Hospitality | 2026 |
| City Capital Finance Limited | Extraterritorial | 1998 |
| City Capital London LLP | | 2003 |
| City Computing Limited | Information & communication | 1983 |
| City Computing Trading Limited | Manufacturing | 2013 |
| City Gate Automation Limited | Professional & scientific | 1996 |
| City Property Investments Limited | Construction | 1987 |
| City View Place Limited | Households | 2019 |
| CJ and SD Keyser Healthcare Limited | Health & social care | 2012 |
| CJR Holdings Limited | Real estate | 2020 |
| CJS Accountancy Limited | Professional & scientific | 2002 |
| Cjsj Consultants Ltd | Professional & scientific | 2021 |
| CL Relocation Specialist Ltd | Transport & logistics | 2020 |
| Clandon Developments Limited | Real estate | 2017 |
| Clandon House Limited | Wholesale & retail | 2003 |
| Clandon Properties Ltd | Real estate | 2017 |
| Clandon Roofing Company Ltd | Construction | 2026 |
| Clandon Wood Limited | Extraterritorial | 2007 |
| Clapham Picture Framers Limited | Wholesale & retail | 2009 |
| Clare Court Residents Limited | Real estate | 1997 |
| Clare Springett Limited | Transport & logistics | 2012 |
| Claregy Ltd | Professional & scientific | 2023 |
| Claremont Quays Management Limited | Other services | 2005 |
| Claremont Waterden Road Limited | Real estate | 1983 |
| Clarity Accounts Limited | Professional & scientific | 2022 |
| Clarity Advisory Group Limited | Professional & scientific | 2016 |
| Clark Equestrian Ltd | Manufacturing | 2018 |
| Clarke Gammon Estates Limited | Real estate | 2015 |
| Clarke Gammon LLP | | 2024 |
| Clarke Property Management Ltd | Real estate | 2008 |
| Clarkhouse Electrical Limited | Construction | 2009 |
| Claspbourne Limited | Professional & scientific | 1978 |
| Clavier Media Company Limited | Other services | 2009 |
| Clay Day Creations Ltd | Arts & recreation | 2024 |
| Clay Lane Valeting Ltd | Professional & scientific | 2023 |
| Clayment Limited | Arts & recreation | 2002 |
| Clean and Green Ltd | Administrative & support | 2022 |
| Clean Homes (Guildford) Limited | Administrative & support | 2002 |
| Clean Sheet Academy Limited | Real estate | 2020 |
| Cleanin Genie Services Ltd | Administrative & support | 2026 |
| Cleanstart Limited | Extraterritorial | 2009 |
| Clear CUT Gardens Tree Care and Landscapes Ltd | Administrative & support | 2015 |
| Clear Minds Psychological Therapy and Assessment Services Ltd | Health & social care | 2026 |
| Clear Structures Limited | Construction | 1987 |
| Clearbooks Consulting Limited | Professional & scientific | 2025 |
| Clearlife Limited | Information & communication | 2007 |
| Clearly Initiatives | Information & communication | 2017 |
| Clearly Initiatives Trading Ltd | Information & communication | 2017 |
| Clearpoint Associates Ltd | Professional & scientific | 2012 |
| Clearwater Plumbing (Surrey) Ltd | Construction | 2024 |
| Cleden Howard & Company Limited | Professional & scientific | 2011 |
| Clemens & Tanner Ltd | Construction | 2015 |
| Clemens and Tanner Holdings Ltd | Financial services | 2019 |
| Clevehurst Residents Association Limited | Households | 1983 |
| CLG Legacy Limited | Financial services | 2022 |
| CLG Protector Limited | Financial services | 2022 |
| Cliche Shisha Cafe Ltd | Hospitality | 2013 |
| Client Services Collective Ltd | Other services | 2025 |
| Client Success Matters Ltd | Professional & scientific | 2024 |
| Clifton House (Guildford) Limited | Extraterritorial | 2004 |
| Climate & Energy Associates Ltd | Professional & scientific | 2014 |
| Clinicology Ltd. | Professional & scientific | 2011 |
| CLK Trader Ltd | Construction | 2017 |
| Clock House Addlestone Limited | Construction | 2026 |
| Clock House LAM Management Company Limited | Households | 2024 |
| Clock Start Limited | Information & communication | 2011 |
| Clockwork Engineering Limited | Construction | 2017 |
| Clockwork Shine Services UK Ltd | Administrative & support | 2026 |
| Cloudhalo IT Limited | Information & communication | 2025 |
| Cloudnine Construction and Developments Limited | Construction | 2025 |
| Clover Occupational Therapy Ltd | Health & social care | 2015 |
| Cloverbloom Digital Ltd | Information & communication | 2025 |
| Cluain BEG Ltd | Construction | 2017 |
| Club Tropicana the Film Limited | Information & communication | 2025 |
| Cluskeys CCP Ltd | Wholesale & retail | 2016 |
| CLX Professionals UK Ltd | Professional & scientific | 2022 |
| CM Asset Development Ltd | Real estate | 2020 |
| CM Squared Ltd | Professional & scientific | 2020 |
| Cmac Protection Ltd | Financial services | 2020 |
| CMB Partnership Limited | Professional & scientific | 2013 |
| Cmcd Construction Ltd | Construction | 2021 |
| CMI Associates Ltd | Professional & scientific | 2017 |
| CN Asset Management Ltd | Real estate | 2020 |
| Co-Pilot Group Limited | Education | 2023 |
| Coached by Anis Ltd | Other services | 2025 |
| Coachel Limited | Administrative & support | 2021 |
| Coachmotiv Limited | Professional & scientific | 2024 |
| Cobalt Project Management Limited | Professional & scientific | 2009 |
| Cobalt Special Projects Limited | Professional & scientific | 2025 |
| Cobbett Freeholders Ltd | Real estate | 2018 |
| Cobbles Property Limited | Real estate | 2012 |