| CLM Care Ltd | Health & social care | 2022 |
| Clocktower Healthcare Ltd | Health & social care | 2010 |
| Clocktower Management Company (Kingswood) Limited | Real estate | 2010 |
| Cloud Color Limited | Information & communication | 2019 |
| Cloud Continuity Ltd | Information & communication | 2023 |
| Cloud Telecom Limited | Information & communication | 2011 |
| Cloud Waters London Ltd | Real estate | 2021 |
| Cloudbooks Ltd | Professional & scientific | 2018 |
| Cloudphase Consultancy Limited | Other services | 2011 |
| Cloudvector Systems Ltd | Information & communication | 2025 |
| Cloverleaf Care Limited | Public administration | 2026 |
| CM Energy Ltd | Professional & scientific | 2025 |
| CMA Mocks Limited | Education | 2022 |
| CMC Contractors & Groundworks Limited | Construction | 2021 |
| CMC Driveways and Paving Limited | Construction | 2022 |
| CMP Innovation Ltd | Information & communication | 2026 |
| CNC Davies Limited | Real estate | 2019 |
| CNJ Management Limited | Administrative & support | 2011 |
| CNL Construction Limited | Construction | 2014 |
| CNR Homes Ltd | Other services | 2018 |
| Co Stars London Ltd | Transport & logistics | 2014 |
| Co-Production Care Limited | Health & social care | 2023 |
| Coal & Spice Limited | Real estate | 2025 |
| Coal City Female Lawyers UK Ltd | Other services | 2025 |
| COASTALPROPERTY4 Ltd | Hospitality | 2014 |
| Cobelli's Ltd | Hospitality | 2012 |
| Code Incubator Limited | Information & communication | 2024 |
| Code-A-Phone Systems International Limited | | 1990 |
| Codewatcher Limited | Information & communication | 2023 |
| Coga AI Limited | Information & communication | 2024 |
| Colin Newland Ltd | Construction | 2015 |
| Colla Limited | Information & communication | 2025 |
| Collecta App Ltd | Information & communication | 2026 |
| Collected Movement Ltd | Administrative & support | 2026 |
| Collectors Clubhouse Ltd | Wholesale & retail | 2026 |
| Collins (Contractors) Group Limited | Financial services | 2024 |
| Colombo Gateway Limited | Wholesale & retail | 2025 |
| Colonial Club Investments LLP | | 2012 |
| Coloproctology JSW Limited | Health & social care | 2023 |
| Color POP Limited | Other services | 2015 |
| Colourhub Services Limited | Professional & scientific | 2024 |
| Colours INK Limited | Construction | 2001 |
| Colvin Wackett Ltd | Professional & scientific | 2020 |
| Colyer Estates Limited | Real estate | 2026 |
| Combined Heat & Power Limited | Construction | 2012 |
| Combined Projects Ltd | Construction | 2023 |
| Commec Property Limited | Real estate | 2019 |
| Commercial & Trade Credit Agencies Limited | Administrative & support | 1988 |
| Commercial Boiler Hire Limited | Administrative & support | 2026 |
| Commercial Stone Limited | Construction | 2004 |
| Commodities Brokers International Limited | Wholesale & retail | 2016 |
| Communico Networking Ltd | Professional & scientific | 2021 |
| Commx Limited | Professional & scientific | 2025 |
| Compass Compliance Limited | Professional & scientific | 2026 |
| Compassion Home Care Limited | Health & social care | 2011 |
| Compassionate Care and Cleaning Services Ltd | Administrative & support | 2025 |
| Compaz Investment Limited | Real estate | 2020 |
| Compex Certification Limited | Education | 1989 |
| Complete Property and Maintenance Solutions Limited | Real estate | 2024 |
| Complete Synergy Ltd | Administrative & support | 2017 |
| Completely US Ltd | Wholesale & retail | 2019 |
| Compliance Consultancy Solutions Limited | Professional & scientific | 2025 |
| Compliant Scaffold Solutions Ltd. | Construction | 2011 |
| Composite Tech Holdings Limited | Manufacturing | 2017 |
| Compstar London Limited | Information & communication | 2008 |
| Computers 4 Business Ltd | Manufacturing | 2010 |
| Comyc UK Ltd | Health & social care | 2019 |
| Concept Professional Landscapes Ltd | Administrative & support | 2014 |
| Conchiglie Software Ltd | Information & communication | 2017 |
| Concrete & Rock Solutions Ltd | Construction | 2009 |
| Concurrence Ltd | Other services | 2017 |
| Conditioned Fitness Ltd | Extraterritorial | 2025 |
| Confluence Publishing Ltd | Information & communication | 2014 |
| Conquerors Covenant Saints Ltd | Other services | 2020 |
| Conrad Management Ltd | Real estate | 2026 |
| Conrad Property Management Ltd | Real estate | 2026 |
| Conservative Friends of the Armed Forces Limited | Other services | 2019 |
| Conservatory Court Freehold Limited | Households | 2018 |
| Considered Cleaner Ltd | Water & waste | 2023 |
| Consolidated Roofing Limited | Construction | 2026 |
| Consolidated Roofing Services Limited | Construction | 2017 |
| Consortium.Legal Ltd | Professional & scientific | 2020 |
| Constellation Clothing Ltd | Wholesale & retail | 2025 |
| Construct IQ Pro Limited | Construction | 2026 |
| Construction & Management Limited | Construction | 1997 |
| Construction Consultants (London) Limited | Professional & scientific | 2010 |
| Construction Skills Support Ltd | Education | 2020 |
| Constructiq Ltd | Construction | 2023 |
| Constructive Cosmetics Ltd | Other services | 2024 |
| Constructive Development & Planning Ltd | Construction | 2013 |
| Constructive Operations Limited | Construction | 2025 |
| Construkt Consulting Limited | Professional & scientific | 2018 |
| Consulberg Limited | Professional & scientific | 2014 |
| Consult Hire Ltd | Information & communication | 2020 |
| Consulture Search Limited | Administrative & support | 2020 |
| Consumer DYE Chem Services UK Ltd | Wholesale & retail | 2022 |
| Container Storage Solutions (Alpha) Ltd | Transport & logistics | 2024 |
| Containment Logic Limited | Water & waste | 2025 |
| Content Consultancy Limited | Professional & scientific | 2018 |
| Continental Shift Ltd | Wholesale & retail | 2017 |