| Calder Court (Langley) Limited | Households | 1965 |
| Calinos Entertainment Limited | Professional & scientific | 2024 |
| Callrise Computers Limited | Information & communication | 1989 |
| Calon Consulting Group Limited | Professional & scientific | 2020 |
| Camber Holdings Ltd | Households | 2016 |
| Cammotion Ltd | Information & communication | 2007 |
| Camunda Ltd | Information & communication | 2020 |
| Canna Kendall Ltd | Extraterritorial | 2021 |
| Capchar Ltd | Manufacturing | 2021 |
| Cape Glass Ltd | Construction | 2022 |
| Capior & Co. Ltd | Professional & scientific | 2010 |
| Capior Limited | Professional & scientific | 2010 |
| Capital Green Limited | Construction | 2008 |
| Carbon Silicon Resources Ltd | Information & communication | 2025 |
| Carbonite Investments Limited | Financial services | 2024 |
| Cardinal SIN Ltd | Wholesale & retail | 2023 |
| Cards of Mimi Limited Ltd | Wholesale & retail | 2025 |
| Caribx (UK) Limited | Mining & quarrying | 2009 |
| Carlton Place Residents Management Company Limited | Households | 2011 |
| Caroline Myall Consulting Ltd | Professional & scientific | 2014 |
| Carvell`S of Marlow Limited | Wholesale & retail | 2008 |
| Casa Global Investments Ltd | Financial services | 2019 |
| Casa Streatham Ltd. | Real estate | 2020 |
| Casar Investments Limited | Financial services | 2020 |
| Case Financial Consulting Limited | Financial services | 2018 |
| Casecoach Ltd | Wholesale & retail | 2018 |
| Cassida Sarah Designs Ltd | Arts & recreation | 2023 |
| Castillon Worldwide Ltd | Administrative & support | 2012 |
| Castle Properties Group Limited | Real estate | 2017 |
| Casual Films International Limited | Information & communication | 2017 |
| Casual Films Limited | Information & communication | 2007 |
| Catalyst Financial Ltd | Professional & scientific | 2022 |
| Catherine Robinson Cashmere Ltd | Wholesale & retail | 2015 |
| Caversham House Management Company Limited | Households | 2020 |
| Caxton House (Reading) Residents Association Limited | Households | 1981 |
| Cbcross Capital Limited | Financial services | 2022 |
| Ccell Renewables Limited | Construction | 2015 |
| Cdrobinson Management Limited | Professional & scientific | 2023 |
| Cecilia Quinn Ltd | Wholesale & retail | 2015 |
| Cecily Pictures Limited | Administrative & support | 2011 |
| Cedar Close RTM Company Ltd | Households | 2015 |
| Cedarlodge Products Ltd | Manufacturing | 2017 |
| Centar Surfacing Ltd | Construction | 2011 |
| Centre for Local Content Innovation Ltd | Professional & scientific | 2019 |
| Cetalis Ltd | Extraterritorial | 2023 |
| CFG Systems Limited | Information & communication | 2018 |
| CFS Group Holdings Ltd | Financial services | 2025 |
| Chainview Consulting Limited | Professional & scientific | 2018 |
| Chairborough Court Management Limited | Real estate | 2012 |
| Chalfont Court Management Limited | Real estate | 1991 |
| Change 4 Limited | Professional & scientific | 2000 |
| Change B2B Ltd | Professional & scientific | 2025 |
| Change Healthcare UK Holdings Limited | Health & social care | 2013 |
| Channoil Consulting Limited | Professional & scientific | 2000 |
| Chareth (Beaumont Court) Limited | Financial services | 2025 |
| Charles Wookey Associates Ltd | Professional & scientific | 2022 |
| Charlies Cars Limited | Transport & logistics | 2004 |
| Charlotte Construction Limited | Construction | 2017 |
| Charman QS Limited | Professional & scientific | 2016 |
| Charmwood Properties Ltd | Real estate | 2019 |
| Charred & Scuffed Ltd | Hospitality | 2026 |
| Chelona Estates Ltd | Real estate | 2025 |
| Chelton CTS Limited | Extraterritorial | 2000 |
| Chelton Defence Communications Limited | Professional & scientific | 2002 |
| Chelton Limited | Manufacturing | 1967 |
| Chemsynergy UK Ltd | Wholesale & retail | 2020 |
| Chesterhouse Holdings Limited | Real estate | 2007 |
| Chesterhouse Lewisham 2 Limited | Administrative & support | 2018 |
| Chesterhouse Properties (Coventry) Limited | Real estate | 1993 |
| Chesterhouse Properties (Lewisham) Limited | Real estate | 2007 |
| Chesterhouse Properties (Loampit) Limited | Real estate | 2016 |
| Chesterhouse Properties (Uxbridge) Limited | Real estate | 2006 |
| Chesterhouse Properties Limited | Real estate | 1993 |
| Chesterhouse Services Limited | Real estate | 2007 |
| Chesterton Commercial (Hanover) Ltd | Real estate | 2012 |
| Chestnut Court (Wokingham) Management Limited | Households | 2005 |
| Child Matters Ltd | Education | 2011 |
| Chiltern Cirrus Limited | Administrative & support | 2020 |
| Chiltern Molecular Ltd | Professional & scientific | 2019 |
| Chiltern Pilates Limited | Other services | 2014 |
| Chiltern Saunas and Spas Limited | Other services | 2025 |
| Chilton Court Management Company (Slough) Limited | Households | 1976 |
| China Health Station Ltd | Extraterritorial | 2013 |
| Chislehurst Properties Limited | Real estate | 2020 |
| Chiswick Lodge Management Company Limited | Households | 1980 |
| Chlober Developments Limited | Construction | 2021 |
| Chlober Limited | Professional & scientific | 2019 |
| Choiceful Consulting Limited | Professional & scientific | 2024 |
| Chrisalyst Ltd | Professional & scientific | 2013 |
| Christopher James Boats Ltd | Wholesale & retail | 2026 |
| Chrome FX Limited | Information & communication | 2010 |
| Church Mews Management Company (Woodley) Limited | Households | 1992 |
| Cimelia Limited | Water & waste | 2009 |
| Cintra House (Management) Limited | Households | 1987 |
| Cirrus Aero Ltd | Professional & scientific | 2024 |
| Cirrus Projects Ltd | Construction | 2020 |
| Cirrus Software (UK) Limited | Information & communication | 2004 |
| Citizen Models Limited | Administrative & support | 2023 |
| CJH Property Limited | Real estate | 2015 |
| CJN Carpentry Ltd | Manufacturing | 2025 |