| Circe Law Ltd | Professional & scientific | 2022 |
| Circle H Polo Limited | Agriculture & fishing | 1997 |
| Circuit Software Ltd | Information & communication | 2025 |
| Circular Code Ltd | Information & communication | 2025 |
| Circular Roots Ltd | Professional & scientific | 2025 |
| Circular Sustainability Ltd | Manufacturing | 2025 |
| Circus 66 Ltd | Information & communication | 2021 |
| Cirrus (Bidco) Limited | Administrative & support | 2024 |
| Cirrus (Midco) Limited | Administrative & support | 2024 |
| Cirrus (Topco) Limited | Administrative & support | 2024 |
| CIS Electrical Ltd | Construction | 2025 |
| Citarnet Limited | Health & social care | 2024 |
| Citizen Wine Limited | Wholesale & retail | 2021 |
| Citriflow Ltd | Construction | 2014 |
| Citrus Leaf Limited | Information & communication | 2002 |
| City 1ST Limited | Wholesale & retail | 1986 |
| City of London Heliport Limited | Professional & scientific | 1989 |
| City-Wills Limited | Professional & scientific | 2020 |
| CITYCABS247 Ltd | Transport & logistics | 2024 |
| Cityhub Ltd | Real estate | 2023 |
| Citystep Analytics Ltd | Professional & scientific | 2024 |
| Civil and Marine (Holdings) Limited | Financial services | 1993 |
| Civil and Marine Limited | Manufacturing | 1988 |
| Civil and Marine Slag Cement Limited | Financial services | 1992 |
| CJ London Services Ltd | Hospitality | 2023 |
| CJC Developments London Limited | Administrative & support | 2017 |
| Cjhh Sports Media Ltd | Information & communication | 2026 |
| Cjjh Sports Media Ltd | Information & communication | 2026 |
| CJP Infotech Ltd | Information & communication | 2022 |
| Ckhk Consultancy Limited | Information & communication | 2014 |
| CL Care and Support Ltd | Administrative & support | 2021 |
| CL NG Ltd | Health & social care | 2014 |
| Claas Transport Ltd | Transport & logistics | 2020 |
| Clackmannanshire Schools Education Partnership (Holdings) Limited | Financial services | 2006 |
| Clackmannanshire Schools Education Partnership Limited | Financial services | 2006 |
| Claire Burrill Limited | Professional & scientific | 2014 |
| Claire Williams Photography Limited | Professional & scientific | 2014 |
| Claire Winter Media Ltd | Professional & scientific | 2021 |
| Claire's Comfy Canines Limited | Administrative & support | 2012 |
| Clairemont Ltd | Real estate | 2020 |
| Clapensar Limited | Real estate | 2016 |
| Clare Norrish Interior Design Ltd | Professional & scientific | 2013 |
| Claremont Accounting Ltd | Professional & scientific | 2000 |
| Clarenmill Limited | Real estate | 1986 |
| Claridge Engineering Limited | Construction | 2016 |
| Clarius Business Services Limited | Professional & scientific | 2009 |
| Clarke Eco Heat Limited | Construction | 2026 |
| Claughton Manor Brick Limited(The) | Professional & scientific | 1898 |
| Clean and Sparkle Limited | Households | 2016 |
| Clear and Concise ISW Assessments Limited | Professional & scientific | 2021 |
| Clear CUT Creation Limited | Wholesale & retail | 2013 |
| Clear Sight Optics Ltd | Health & social care | 2024 |
| Clear Technology Consulting Limited | Information & communication | 2020 |
| Clear View Data Solutions Ltd | Information & communication | 2023 |
| Clearsky Products Ltd | Wholesale & retail | 2021 |
| Clearthink Limited | Professional & scientific | 2014 |
| Clements Tree Care Limited | Administrative & support | 2021 |
| Cleo Software UK Limited | Administrative & support | 2016 |
| Click People Consulting Ltd | Professional & scientific | 2022 |
| Clickcom Ltd | Information & communication | 2019 |
| Clickmark Ltd | Professional & scientific | 2026 |
| Cliffeville Limited | Water & waste | 1980 |
| Clinic Trek Ltd | Information & communication | 2024 |
| Clinical Witness Reports Ltd | Health & social care | 2023 |
| Clinogen Limited | Manufacturing | 2002 |
| Clinogen Medical Ltd | Professional & scientific | 1998 |
| Clintfl Limited | Information & communication | 2012 |
| Clip IT Solutions Ltd | Information & communication | 2002 |
| Cliveden Conservation Workshop Limited | Other services | 1990 |
| Clixaro Ltd | Wholesale & retail | 2026 |
| Clock END Courier Ltd | Transport & logistics | 2026 |
| Clocktowerweb Limited | Information & communication | 2000 |
| Clothing 4 Events Limited | Wholesale & retail | 2004 |
| Clothing 4 U Ltd | Wholesale & retail | 2021 |
| Clothing for Safety Limited | Wholesale & retail | 2026 |
| Cloud & Digital Services Ltd | Information & communication | 2019 |
| Cloud Angel Ltd | Financial services | 2016 |
| Cloud Fortune UK Ltd | Information & communication | 2020 |
| Cloud Horsepower Ltd | Information & communication | 2016 |
| CLOUD360 Solutions Limited | Information & communication | 2008 |
| Clouddna Limited | Information & communication | 2012 |
| Clove Consulting Limited | Professional & scientific | 2014 |
| Clubciso Limited | Administrative & support | 2026 |
| Cluck Invest Group Ltd | Real estate | 2023 |
| Clusterdb Ltd. | Information & communication | 2013 |
| Clutch Creative Ltd | Wholesale & retail | 2021 |
| CM C Contracting Service Ltd | Professional & scientific | 2019 |
| CM Social Work Solutions Ltd | Health & social care | 2024 |
| CMF Group Limited | Financial services | 2008 |
| CML Digital Ltd | Information & communication | 2018 |
| CNC Taplow (Management) Limited | Real estate | 1988 |
| Co Print Labs Limited | Manufacturing | 2022 |
| Coach Triumph Limited | Other services | 2020 |
| Coaching and Mentoring International Ltd | Professional & scientific | 2012 |
| Coaley Consulting Ltd | Administrative & support | 2015 |
| Cobalt Morning Limited | Professional & scientific | 1999 |
| Cobanfood Ltd | Wholesale & retail | 2025 |
| Coco Road Limited | Wholesale & retail | 2017 |
| Cocoon Wellbeing Limited | Health & social care | 2019 |
| CODE3 Property Limited | Real estate | 2023 |