| Clarence Estates (Kingston on Thames) Limited | Real estate | 1939 |
| Clarence House Healthcare Limited | Health & social care | 2026 |
| Clarendon Court (MV) RTM Company Limited | Households | 2007 |
| Clareville Grove Limited | Real estate | 2011 |
| Clariti Consulting Limited | Administrative & support | 2013 |
| Classical Energy Limited | Administrative & support | 2024 |
| Clavelle INT Ltd | Information & communication | 2019 |
| Clayytech Ltd | Information & communication | 2024 |
| Clean CUT Media Limited | Information & communication | 2006 |
| Clean Fast 247 Limited | Administrative & support | 2024 |
| Cleaned and Cleaner Ltd | Administrative & support | 2024 |
| Clear Arrears Ltd | Administrative & support | 2015 |
| Clear Path Learning Hub Limited | Education | 2025 |
| Clearwater Place Apartments RTM Company Limited | Households | 2007 |
| Clearwater Place Ltd | Households | 2009 |
| Clearyolk Limited | Information & communication | 2021 |
| Cleavewater 2 Limited | Construction | 2024 |
| Cleavewater Developments Ltd | Financial services | 2023 |
| Cleavewater Limited | Construction | 2022 |
| Cleecorp Limited | Information & communication | 2017 |
| Clermont-Ferrand Ltd | Households | 2021 |
| Cleve West Ltd | Administrative & support | 2016 |
| Clevehurst (Weybridge) Management Limited | Households | 1999 |
| Clevland Consulting Limited | Professional & scientific | 2009 |
| Click Photographic Workshops Limited | Education | 2010 |
| Client Impact Awards Limited | Administrative & support | 2026 |
| Clifton Investments Ltd | Construction | 2013 |
| Climate Habits Ltd | Professional & scientific | 2021 |
| Climate Risk Pathways Ltd | Professional & scientific | 2024 |
| Clingtons Limited | Real estate | 1992 |
| Clingtons Property Investment and Management Limited | Real estate | 2020 |
| Clinicalmed Ltd | Professional & scientific | 2022 |
| Clipping Path India Limited | Information & communication | 2025 |
| Close-Up Films Ltd | Information & communication | 2020 |
| Cloud Governance Ltd | Administrative & support | 2010 |
| Cloud IS IT Ltd | Information & communication | 2011 |
| Cloud Tuned Ltd | Information & communication | 2019 |
| Cloudberry Solutions Limited | Professional & scientific | 2018 |
| Cloudbreak Analysis Limited | Professional & scientific | 2011 |
| Cloudcare Software Ltd | Administrative & support | 2015 |
| CLOUDMINUS89 Ltd | Information & communication | 2011 |
| Clovely Ltd | Real estate | 2014 |
| Clover Trades Limited | Financial services | 2014 |
| Club ENA Ltd | Wholesale & retail | 2025 |
| Club Monaco Investments Limited | Wholesale & retail | 1997 |
| Club Safety Car | Administrative & support | 2015 |
| Cmcc Consultants Ltd | Professional & scientific | 2023 |
| Cmdg Limited | Administrative & support | 2013 |
| Cmgr Ltd | Information & communication | 2026 |
| CMH Wholesale Ltd | Wholesale & retail | 2025 |
| CMT Systems(Gb) Ltd | Information & communication | 2015 |
| Cmyk EU for Printing Solutions Ltd | Wholesale & retail | 2022 |
| CMZ Global Ltd | Real estate | 2019 |
| CNC Sonography Limited | Administrative & support | 2015 |
| Cnfood Ltd | Wholesale & retail | 2020 |
| Co & Bear Productions (UK) Limited | Information & communication | 1996 |
| Co Investing Ltd | Households | 2025 |
| Coaching and Therapy Academy Ltd | Other services | 2019 |
| Coastal Horizons Limited | Real estate | 2022 |
| Cobalt Property Holdings Ltd | Real estate | 2022 |
| Cobanford Limited | Extraterritorial | 2015 |
| Cobanshield Limited | Extraterritorial | 2015 |
| Cobham Academy Limited | Education | 2013 |
| Coceptual Limited | Professional & scientific | 2019 |
| Coco and Lime Limited | Other services | 2020 |
| Coco Chicken and Waffle Ltd | Hospitality | 2020 |
| Cocoon Hair Limited | Other services | 2026 |
| Codeblam Limited | Information & communication | 2014 |
| Coderium Ltd | Information & communication | 2019 |
| Coffee & Pages Ltd | Wholesale & retail | 2025 |
| Coffee Buy the Kilo Limited | Extraterritorial | 2021 |
| Cognaix Ltd | Professional & scientific | 2020 |
| Coherent Research Limited | Manufacturing | 1989 |
| Coherent Technologies Limited | Manufacturing | 1990 |
| Coles-Porter Holding Ltd | Financial services | 2026 |
| Colindo London Ltd | Other services | 2018 |
| Collaboration Group Limited | Construction | 2017 |
| Collards Limited | Professional & scientific | 2007 |
| Collateral Global | Health & social care | 2020 |
| Collect 4 Reuse Ltd | Wholesale & retail | 2023 |
| Collective Creative Limited | Administrative & support | 1997 |
| Collective Wick Limited | Administrative & support | 2006 |
| College Gardens Residents Company Limited | Households | 1989 |
| College of Independent Trainers Limited | Education | 2023 |
| Collingham Trading Limited | Real estate | 1993 |
| Collisionx Solutions Limited | Professional & scientific | 2023 |
| Color Experts International Limited | Information & communication | 2025 |
| Colourwheel Kingston Upon Thames Ltd | Education | 2026 |
| Colourz Properties Ltd | Real estate | 2016 |
| Columbia Lake Partners Growth Lending (Holdings SUB), Limited | Financial services | 2014 |
| Columbia Lake Partners Manager, LLP | | 2014 |
| Comment Consulting Limited | Professional & scientific | 2019 |
| Commercial & Industrial Lighting Solutions Ltd | Construction | 2011 |
| Common Belonging UK | Other services | 2026 |
| Commons at Events Ltd | Hospitality | 2025 |
| Comms Business Limited | Information & communication | 2015 |
| Community Parks Tennis Ltd | Education | 2021 |
| Communiverse Solutions Ltd | Information & communication | 2000 |
| Comnetrix IT Services Limited | Information & communication | 1999 |
| Companionship Supported Travel Ltd | Transport & logistics | 2023 |