| Configure One Europe, Ltd. | Information & communication | 2006 |
| Configure One Holdings Limited | Information & communication | 2012 |
| Confris Ltd | Information & communication | 2025 |
| Connect Infrastructure Ltd | Information & communication | 2024 |
| Connect Private Limited | Wholesale & retail | 2018 |
| Connect to Success Ltd | Education | 2025 |
| Connectors Cables Specialists (CCS) Limited | Wholesale & retail | 1983 |
| Connexion Career Collective Ltd | Other services | 2025 |
| Consilium EV Ltd | Construction | 2015 |
| Consistent Property Ltd | Real estate | 2020 |
| Consistent Recruitment Ltd | Administrative & support | 2018 |
| Constrail Group Ltd | Construction | 2024 |
| Construct Glass Limited | Manufacturing | 2019 |
| Construction Services East London Limited | Construction | 2007 |
| Consult 313 Limited | Administrative & support | 2015 |
| Content Backdrops Ltd | Professional & scientific | 2021 |
| Contrast Solutions Ltd | Transport & logistics | 2007 |
| Control Wise Ltd | Construction | 2025 |
| Cook's Quality Foods Limited | Wholesale & retail | 2007 |
| Cooper Rason Limited | Manufacturing | 2004 |
| Copleys Food Limited | Manufacturing | 2018 |
| Copper Beech View Newport Ltd | Households | 2023 |
| Copper Court Freehold Company Limited | Households | 2015 |
| Coppin Place RTM Company Limited | Households | 2011 |
| Cordial Limited | Wholesale & retail | 2023 |
| Core Care Personnel Limited | Administrative & support | 2023 |
| Core Jurists & Assets Ltd | Professional & scientific | 2026 |
| Core Quest NOW Limited | Health & social care | 2025 |
| Coremed Services Ltd | Health & social care | 2026 |
| Cornard Road Block "D" Management Company Limited | Households | 1990 |
| Cornell Partnership Search Ltd | Administrative & support | 2012 |
| Cornerstone Facility Service Management Ltd | Extraterritorial | 2023 |
| Coronam Limited | Other services | 2020 |
| Corp SEC Services Limited | Professional & scientific | 2025 |
| Corpinelab Limited | Information & communication | 2024 |
| Corporate Cleaning and Maintenance Limited | Administrative & support | 2017 |
| Corporate Consulting Limited | Information & communication | 2015 |
| Corporate Golfing Events Limited | Arts & recreation | 2025 |
| Corvale Limited | Manufacturing | 1997 |
| Cory Services Limited | Transport & logistics | 2024 |
| COS Carpentry Limited | Manufacturing | 2025 |
| Cosmo Films Ltd | Information & communication | 2018 |
| Costa's Premium Limited | Transport & logistics | 2023 |
| Costad Construction Ltd | Construction | 2026 |
| Costan Construction Ltd | Construction | 2025 |
| Costel Nastac Ltd | Wholesale & retail | 2026 |
| Cosy EHS Professionals Limited | Administrative & support | 2014 |
| Cotch & Co Ltd | Professional & scientific | 2022 |
| Cotton Park Gardens (Romford) Management Company Limited | Households | 2004 |
| Cougar Lubricants (UK) Limited | Wholesale & retail | 2013 |
| Cougar Lubricants International Limited | Manufacturing | 2013 |
| Country Fashion Limited | Manufacturing | 2003 |
| County Dents Ltd | Wholesale & retail | 2004 |
| County Hall Freehold Limited | Administrative & support | 2018 |
| County Hall Management Company (Courtyard) Limited | Households | 1997 |
| County Hall Management Company (N & S) Limited | Households | 1995 |
| Courtenay Building Contractors Limited | Construction | 1986 |
| Courtland House Limited | Real estate | 2003 |
| Courtlands Waste Management (UK) Limited | Water & waste | 2009 |
| Courtmans Properties Ltd | Real estate | 2024 |
| Covermy Group Limited | Professional & scientific | 2005 |
| Covermy Ltd | Financial services | 2011 |
| Coveted Collectibles TCG Ltd | Wholesale & retail | 2025 |
| Cozmo Limited | Wholesale & retail | 2020 |
| CPD OIL and Chemicals Ltd | Wholesale & retail | 2024 |
| CPR House Limited | Households | 2016 |
| Crafty Caves Limited | Wholesale & retail | 2018 |
| Craig House (Blackheath) Limited | Households | 1984 |
| Craighead Ltd | Professional & scientific | 2020 |
| Crazy Camp-In Ltd | Arts & recreation | 2020 |
| Create Identikit Ltd | Wholesale & retail | 2014 |
| Create Identitee Limited | Wholesale & retail | 2010 |
| Creative Flooring (Harlow) Limited | Administrative & support | 2016 |
| Creative Muslimeen Ltd | Education | 2022 |
| Creative Union Limited | Professional & scientific | 2016 |
| CRESCENT12 Ltd | Wholesale & retail | 2026 |
| Crest Environmental Limited | Construction | 1999 |
| Crestfield Ltd | Health & social care | 2025 |
| Crestmed Limited | Other services | 2023 |
| Crestwood Limited | Administrative & support | 2006 |
| Crevina Flat Management Company Limited | Households | 1976 |
| Crewzoom Solutions Ltd | Transport & logistics | 2024 |
| Cricketers Close RTM Company Limited | Households | 2009 |
| Crimson Gate Studios Ltd | Information & communication | 2025 |
| Crimson Property Management Limited | Construction | 2025 |
| Cris Construction Ltd | Construction | 2016 |
| Cris Solution Ltd | Transport & logistics | 2016 |
| Criscione Limited | Professional & scientific | 2024 |
| Crisp & Clean Services Ltd | Administrative & support | 2026 |
| Cristea Transport Limited | Construction | 2019 |
| Cristian G Trans Ltd | Transport & logistics | 2025 |
| Cristinel Transport Ltd | Transport & logistics | 2016 |
| CRJ Facilities Management Limited | Construction | 2024 |
| CRM Amusements Limited | Arts & recreation | 2018 |
| Crmgn Developments Limited | Construction | 2024 |
| Croco Floral Limited | Wholesale & retail | 2026 |
| Croft House Freehold Limited | Households | 2012 |
| Crofton Way, Enfield (Management) Limited | Households | 1979 |
| Crojoe Limited | Information & communication | 2015 |
| Crosby Refurbishments Limited | Professional & scientific | 2003 |