| Clearspace Home Solutions Ltd | Transport & logistics | 2026 |
| Clearvue Builders Limited | Construction | 2025 |
| Clearway Contractors Ltd | Administrative & support | 2025 |
| Clearway Maintenance Ltd | Construction | 2018 |
| Cleatskins Ltd | Wholesale & retail | 2024 |
| Clementine Way Management Company Limited | Households | 2005 |
| Clements Estate Agents Limited | Real estate | 2008 |
| Clements Gate (Hawkwell) Residents Company Limited | Households | 2013 |
| Cleopatra's Jamaica FOOD4U Ltd | Hospitality | 2026 |
| Cleotail Limited | Wholesale & retail | 2021 |
| Click London Limited | Professional & scientific | 2020 |
| Clickinon Web Innovations Limited | Information & communication | 2012 |
| Clifton Stone Ltd | Extraterritorial | 2002 |
| Climate Facilities Ltd | Construction | 2025 |
| Climate Services 4 U Limited | Energy | 2014 |
| Clinovo Ltd | Professional & scientific | 2025 |
| Clive Bell Limited | Information & communication | 2018 |
| Clixia Ltd | Wholesale & retail | 2026 |
| Closeteam Ltd | Construction | 2023 |
| Cloud Based Solutions Ltd | Wholesale & retail | 2022 |
| Cloud Bidco Limited | Health & social care | 2015 |
| Cloud Callss LLP | | 2024 |
| Cloud I Tech Solutions Ltd | Information & communication | 2018 |
| Cloud Midco Limited | Health & social care | 2015 |
| Cloud Topco Limited | Health & social care | 2015 |
| CLOUD9 Business Services Limited | Information & communication | 2017 |
| Cloudcombe Limited | Information & communication | 1999 |
| Cloudd Calls Limited | Wholesale & retail | 2026 |
| Cloudfive Limited | Hospitality | 2024 |
| Clovelly Holiday Park Limited | Arts & recreation | 2025 |
| Clownhouse Productions Ltd | Construction | 2024 |
| Clupea Services Limited | Wholesale & retail | 2025 |
| CM Wilson and Sons Ltd | Construction | 2016 |
| CMA Trading Ltd | Wholesale & retail | 2022 |
| CMN Digital Limited | Information & communication | 2021 |
| CMS VAT Services Limited | Other services | 2018 |
| CMV Cleaning Ltd | Other services | 2020 |
| Cmyk Strategies Ltd | Manufacturing | 2026 |
| CNL Builders Ltd | Construction | 2024 |
| CNL Projects Ltd | Administrative & support | 2025 |
| Co Site Engineering Ltd | Construction | 2020 |
| Coach OZ Limited | Professional & scientific | 2015 |
| Coachsense Group Limited | Financial services | 2025 |
| Coastal Parks Hold Limited | Administrative & support | 2012 |
| Coates Consultancy Limited | Administrative & support | 2007 |
| Cobham Services Limited | Administrative & support | 2019 |
| Cobra Deals Ltd | Transport & logistics | 2019 |
| Coconut Digital Ltd | Professional & scientific | 2009 |
| Cocoon Support Ltd | Health & social care | 1986 |
| Code Pulse 1 Limited | Information & communication | 2025 |
| Codecrafters PVT Ltd | Information & communication | 2025 |
| Codenville Consulting Ltd | Information & communication | 2012 |
| Codicote Homes Limited | Construction | 2019 |
| Coeburn Property Limited | Households | 2002 |
| Coel Ltd | Professional & scientific | 2018 |
| Coffee and Smoothie Specialist Ltd | Hospitality | 2025 |
| Coffee ME Ltd | Hospitality | 2025 |
| Cogno AI Limited | Information & communication | 2025 |
| Coin Solutions International Ltd | Administrative & support | 2023 |
| Cojvasil Ltd | Transport & logistics | 2018 |
| Coker-Brown School of Riding Ltd | Education | 2015 |
| Coker-Brown School of Vaulting Ltd | Education | 2023 |
| Cole Bros Plumbing & Heating Limited | Construction | 2016 |
| Colin Morgan Consulting Ltd | Administrative & support | 2016 |
| Colkim Properties Limited | Real estate | 2017 |
| Collectivly Limited | Information & communication | 2020 |
| Collett Aviation Services Ltd | Other services | 2017 |
| Colleycare Limited | Health & social care | 1988 |
| Colman Properties Ltd | Real estate | 2022 |
| Colmec Limited | Construction | 2014 |
| Colour Booth Limited | Manufacturing | 1989 |
| Colourbyte Europe Limited | Wholesale & retail | 1997 |
| Colourbyte Limited | Extraterritorial | 1998 |
| Colouring to Chillax Ltd | Wholesale & retail | 2024 |
| Colours (Lucca Apartments) Management Company Limited | Households | 2010 |
| Colours (Manvers Way) Management Company Limited | Households | 2007 |
| Coloursplash Painters Ltd | Information & communication | 2013 |
| Combustion Limited | Professional & scientific | 2002 |
| Comet Accountants Limited | Professional & scientific | 2025 |
| Comfortech Electrical Ltd | Construction | 2023 |
| Comfortech Ltd | Financial services | 2023 |
| Comics FC Ltd | Wholesale & retail | 2022 |
| Command Secondary School JOS Alumni UK CIC | Health & social care | 2026 |
| Commerce Consultancy Ltd | Professional & scientific | 2018 |
| Commercial Clean 4 YOU Ltd | Administrative & support | 2014 |
| Commercial Construction and Building Services Limited | Professional & scientific | 2014 |
| Commercial Intertech Limited | Extraterritorial | 1961 |
| Commercial Logistics Services Ltd | Transport & logistics | 2020 |
| Commodore Investments Ltd | Real estate | 2025 |
| Commonwood Fitted Furniture Ltd | Wholesale & retail | 2019 |
| Comon Bond Services Limited | Health & social care | 2013 |
| Companion Mental Health Limited | Information & communication | 2023 |
| Company Advisory Services Ltd | Professional & scientific | 1996 |
| Compassionate Herts Ltd | Administrative & support | 2016 |
| Complete Ceiling Solutions Ltd | Construction | 2023 |
| Complete Finish Ltd | Construction | 2012 |
| Complete Reformer Community Education & Rehab Limited | Health & social care | 2025 |
| Complex JR Construction Ltd | Construction | 2016 |
| Comprehensive Telecommunications PLC. | | 1985 |
| Compress Ltd | Real estate | 2026 |