| Consulting Tech Ltd | Information & communication | 2022 |
| Consumer Assist Ltd | Extraterritorial | 2012 |
| Consumer Reclaim Limited | Administrative & support | 2010 |
| Continental Cottage Limited | Wholesale & retail | 2005 |
| Continental Energy Services Limited | Professional & scientific | 2025 |
| Continuity 22301 Ltd | Professional & scientific | 2011 |
| Continuous Improvement Coaching Ltd | Professional & scientific | 2023 |
| Continuum Consulting Limited | Other services | 2010 |
| Continuum Design & Project Services Limited | Administrative & support | 2007 |
| Continuum Project Services Ltd | Administrative & support | 2026 |
| Contour Coverings Ltd | Manufacturing | 2025 |
| Contracts Management Resources Limited | Administrative & support | 2015 |
| Contrast Planning Solutions Ltd | Professional & scientific | 2021 |
| Contrived Capital Ltd. | Extraterritorial | 2019 |
| Control & Automation Solutions Limited | Administrative & support | 2007 |
| Control & Systems Engineering Limited | Information & communication | 2001 |
| Control Change Limited | Administrative & support | 2013 |
| Convertabath Ltd | Construction | 2022 |
| Conveyor Networks Limited | Professional & scientific | 2020 |
| Conway Control Systems Limited | Manufacturing | 2002 |
| Conway Phillips Limited | Administrative & support | 2008 |
| Conwy Valley Engineering Limited | Administrative & support | 2015 |
| Cooktime Limited | Administrative & support | 2015 |
| Coombes Property Portfolio Limited | Real estate | 2023 |
| Coombes Psychological Therapies Limited | Health & social care | 2021 |
| Cooper Agri Services Group Limited | Financial services | 2024 |
| Cooper Barnes Metals Limited | Extraterritorial | 1929 |
| Cooper Bidco Limited | Extraterritorial | 2015 |
| Cooper Business Consultants Ltd | Professional & scientific | 2010 |
| Cooper Engineering Ltd | Administrative & support | 2026 |
| Cooper Farm Services Ltd | Other services | 2015 |
| Cooper Topco Limited | Financial services | 2015 |
| Coopers Castles Limited | Hospitality | 2025 |
| Coopers Holdings Limited | Extraterritorial | 1982 |
| Coopers Metals (Holdings) Limited | Extraterritorial | 1953 |
| Coord & Works Limited | Other services | 2017 |
| Coordinatingservices Limited | Wholesale & retail | 2025 |
| Copper Engineering Services Ltd | Professional & scientific | 2023 |
| Coppertown Solutions Ltd | Administrative & support | 2026 |
| Copperwood Home Ltd | Wholesale & retail | 2025 |
| Copyrite Properties Limited | Hospitality | 2016 |
| Coral Subsea Limited | Mining & quarrying | 2014 |
| Corax Solutions Ltd | Administrative & support | 2016 |
| Corb Automation Ltd | Information & communication | 2024 |
| Corbel Partners Limited | Financial services | 2004 |
| Corbetts Support Solutions Limited | Manufacturing | 2005 |
| Corbetts Support Systems Limited | Manufacturing | 2011 |
| Corbuilt Properties Limited | Construction | 2018 |
| Corby Eats Ltd | Hospitality | 2025 |
| Cordillera Consultancy Ltd | Professional & scientific | 2024 |
| Cordis Medical UK Limited | Wholesale & retail | 2021 |
| Cordtech Limited | Administrative & support | 2009 |
| Core and Chorus Ltd | Education | 2026 |
| Core Social Limited | Professional & scientific | 2022 |
| Core Special Projects Limited | Construction | 2004 |
| Coremonkeys Ltd | Information & communication | 2019 |
| Coresap Services Limited | Administrative & support | 2010 |
| Coreshare Limited | Information & communication | 2001 |
| Coreshare Technology Ltd | Information & communication | 2017 |
| Coretech Electrical Solutions Ltd | Construction | 2021 |
| Corfield HR Recruitment Limited | Administrative & support | 2025 |
| Corflynn Ltd | Information & communication | 2025 |
| Corin Silva Limited | Arts & recreation | 2023 |
| Corincase Limited | Professional & scientific | 1988 |
| Corker Solutions Limited | Administrative & support | 2014 |
| Corkers Pharmacy Limited | Wholesale & retail | 2005 |
| Corkie Superfly Ltd | Administrative & support | 2026 |
| Corks OUT (Warrington) Ltd | Wholesale & retail | 2019 |
| Corks OUT UK Ltd | Wholesale & retail | 2019 |
| Corlet Limited | Real estate | 2013 |
| Corneo Solutions Limited | Wholesale & retail | 2023 |
| Corneologic Limited | Wholesale & retail | 2024 |
| Cornerstone Accountancy Services Limited | Professional & scientific | 2025 |
| Cornerstone Advisory MK Ltd | Professional & scientific | 2026 |
| Cornerstone Coffee Ltd | Hospitality | 2024 |
| Cornerstone Engineering (UK) Limited | Construction | 1998 |
| Cornerstone Solution Architecture Ltd | Administrative & support | 2026 |
| Cornflower Analytics Ltd | Information & communication | 2024 |
| Cornforth Manufacturing Consultancy Limited | Administrative & support | 2023 |
| Cornwall 3D Modelling Limited | Professional & scientific | 2007 |
| Coronado Controls Limited | Wholesale & retail | 1995 |
| Corp Advisors Limited | Information & communication | 2015 |
| Corporate Acquisition Limited | Professional & scientific | 2012 |
| Corporate Group Consulting Limited | Information & communication | 2015 |
| Corpus Legem Ltd | Information & communication | 2018 |
| Corroventa Limited | Administrative & support | 1999 |
| Corrybrough Design Consultancy Limited | Professional & scientific | 2017 |
| Cortex Accounting and Tax Advisors LLP | | 2011 |
| Cortova Limited | Professional & scientific | 2021 |
| Cosette Consulting Ltd | Administrative & support | 2020 |
| Cosgrove Operations Ltd | Administrative & support | 2025 |
| Cosigna Ltd | Administrative & support | 2025 |
| Cosmetic Couture Culcheth Ltd | Health & social care | 2020 |
| Cosmeticconsult Ltd | Other services | 2021 |
| Cosmeticconsult Skin Ltd | Wholesale & retail | 2024 |
| Cosmic Delight Ltd | Hospitality | 2026 |
| Cosmic Joke Ltd | Information & communication | 2012 |
| Cosmic Labs Ltd | Information & communication | 2018 |
| Cosmos Legal Limited | Professional & scientific | 2017 |
| Cost Care R D Limited | Administrative & support | 1998 |