| Click Style Limited | Wholesale & retail | 2022 |
| CLICK-2-HEEL Ltd | Education | 2018 |
| Clifford Water Compliance Ltd | Professional & scientific | 2025 |
| Clinical Consultation Partnerships Ltd | Health & social care | 2026 |
| Clinprotocol Management Limited | Professional & scientific | 2021 |
| Cloud Aspiro Limited | Information & communication | 2013 |
| Cloudlake Consultancy Ltd | Information & communication | 2025 |
| Cloudpros Technology Private Ltd | Information & communication | 2022 |
| Cloudxcel Ltd | Information & communication | 2021 |
| Clover Equine Services Limited | Transport & logistics | 2019 |
| Clover Polo Ltd | Agriculture & fishing | 2017 |
| Clumic Beauty Ltd | Wholesale & retail | 2022 |
| CM Omnichannel Ltd | Administrative & support | 2016 |
| CME Electrical Ltd | Construction | 2020 |
| CMI Healthcare Services Ltd | Manufacturing | 1991 |
| CMI Holdings Limited | Professional & scientific | 2004 |
| Cmos Solutions Limited | Information & communication | 2010 |
| Cmyk Europe Ltd | Administrative & support | 2025 |
| Cmyuk Digital Ltd | Administrative & support | 2005 |
| Cmyuk Limited | Administrative & support | 2002 |
| CNW Construction LLP | | 2019 |
| Co Property Maintenance and Services Ltd | Construction | 2026 |
| Cobra Security Solutions Limited | Financial services | 2018 |
| Code and Consult Limited | Wholesale & retail | 2015 |
| Code Mood Limited | Arts & recreation | 2024 |
| Codeko Estates Limited | Construction | 2019 |
| Codeko Homes Limited | Health & social care | 2018 |
| Coffee & Stuff Limited | Wholesale & retail | 2016 |
| Cohesion FX Limited | Information & communication | 2017 |
| Colbyco Limited | Real estate | 2016 |
| Coleman Marketing Limited | Professional & scientific | 2020 |
| Coleman Personal Training Limited | Health & social care | 2016 |
| Collins Executive Cars Limited | Manufacturing | 2016 |
| Collins Structures Limited | Construction | 2023 |
| Collinsgate Limited | Professional & scientific | 2025 |
| Columbia SPV Limited | Administrative & support | 2023 |
| COM DEV Europe Limited | Information & communication | 1984 |
| Combustion Boilerhouse Services Limited | Wholesale & retail | 1986 |
| Comfort in Care Ltd | Health & social care | 2021 |
| Comfort Living 4U Ltd | Health & social care | 2020 |
| Comfort Supported Housing Ltd | Real estate | 2021 |
| Comfort Town Ltd | Construction | 2024 |
| Commercial Surveying Group Limited | Real estate | 2021 |
| Community Homes of Intensive Care and Education Limited | Health & social care | 1992 |
| Compensation Research Limited | Administrative & support | 1998 |
| Compete PR Ltd | Other services | 2012 |
| Complete Building and Roofing Solutions Ltd | Construction | 2025 |
| Complete Project Building Services Limited | Construction | 2013 |
| Compliance Guidance Ltd | Professional & scientific | 2020 |
| Comply Gdpr Ltd | Professional & scientific | 2019 |
| COMPLYB4 Ltd | Information & communication | 2025 |
| Compressor Controls UK Limited | Financial services | 2008 |
| Computers House Ltd | Wholesale & retail | 2010 |
| Conbea UK Engineering Limited | Manufacturing | 2015 |
| Concept 17 Projects Ltd | Construction | 2020 |
| Conchx Ltd | Information & communication | 2015 |
| Confident Kids Ltd | Education | 2026 |
| Confido Property Limited | Real estate | 2023 |
| Confido Talent Limited | Administrative & support | 2018 |
| Confido Talent Partners Limited | Professional & scientific | 2020 |
| Conlan Piper Limited | Professional & scientific | 2002 |
| Connect Haven (UK) Ltd | Wholesale & retail | 2019 |
| CONNECT44 Newco Ltd | Information & communication | 2026 |
| Connected Architecture Limited | Professional & scientific | 2017 |
| Connected Architecture, Planning and Design Ltd | Professional & scientific | 2026 |
| Connected Loft Rooms Limited | Construction | 2026 |
| Connective-Link Services Ltd | Administrative & support | 2022 |
| Consent Systems Ltd | Information & communication | 2017 |
| Consolidated Medical Industries Limited | Manufacturing | 1980 |
| Construct Safe Ltd | Construction | 2018 |
| Consultancy Care Limited | Administrative & support | 2011 |
| Consultancy Code Ltd | Agriculture & fishing | 2014 |
| Consumer Code for New Homes Limited | Financial services | 2015 |
| Content Guru Limited | Information & communication | 2005 |
| Contract Cleaning Services (SL) Limited | Administrative & support | 2016 |
| Contract Cleaning Solutions Ltd | Administrative & support | 2013 |
| Control Loop Concepts Limited | Professional & scientific | 2004 |
| Controlancy Limited | Information & communication | 1986 |
| Cook and Simpson Developments Limited | Real estate | 2016 |
| Cool Integrity Ltd | Manufacturing | 2025 |
| Coopers Home & Property Services Ltd | Real estate | 2025 |
| Copacabana Holdings Limited | Financial services | 2024 |
| Copi Group UK Ltd | Financial services | 2017 |
| Copi Studio Limited | Agriculture & fishing | 2017 |
| Copier Logistics Limited | Transport & logistics | 2020 |
| Copycontainer Ltd | Information & communication | 2025 |
| Coralfern Limited | Transport & logistics | 2015 |
| Coregrid IT Ltd | Information & communication | 2025 |
| Corporel Aesthetics Ltd | Financial services | 2021 |
| Correllatn Ltd | Wholesale & retail | 2025 |
| Cortile Deli Ltd | Wholesale & retail | 2023 |
| Cossey & Ward Ltd | Information & communication | 2014 |
| Country Mouse Limited | Wholesale & retail | 2012 |
| Country Site Properties Limited | Real estate | 2020 |
| Countrywide Corporate Property Services Limited | Real estate | 2004 |
| Courvoisier Limited | Extraterritorial | 2025 |
| Coverglobe Limited | Information & communication | 2020 |
| CP Pharm Limited | Health & social care | 2010 |
| CPK Consultants Limited | Health & social care | 2014 |
| CPU Global Links Ltd | Professional & scientific | 2018 |