| C.F. Capital Holdings Limited | Financial services | 2019 |
| C.F. Capital PLC | Financial services | 1988 |
| Cablefix Ltd | Information & communication | 2024 |
| Cage END (Hatfield Broad Oak) Management Limited | Households | 2026 |
| Cambridge Funeral Services Limited | Extraterritorial | 1991 |
| Capital Construction (Contractors) Ltd. | Construction | 2015 |
| Capital Deep Clean Services (Holdings) Limited | Financial services | 2024 |
| Capital Pest Control Services (Holdings) Limited | Financial services | 2024 |
| Carmelcrest Comfort Ltd | Construction | 2026 |
| Carmelcrest Holdings Ltd | Financial services | 2022 |
| Carmelcrest Lettings Ltd | Real estate | 2026 |
| Caroline Last Limited | Administrative & support | 2014 |
| Castlebrook Holdings Limited | Real estate | 1967 |
| Castlebrook Properties Limited | Real estate | 1974 |
| Caxton Advisory Ltd | Professional & scientific | 2022 |
| Cctv in Focus Ltd | Administrative & support | 2006 |
| Celal Bartender Ltd | Hospitality | 2018 |
| Ceres Interiors Limited | Construction | 2019 |
| Chalkgate Properties Ltd | Real estate | 2021 |
| Chalkstone Property Ltd | Real estate | 2024 |
| Champel Ltd | Real estate | 2025 |
| Chandlers Services Ltd | Extraterritorial | 2021 |
| Changing Visions Consultancy Limited | Professional & scientific | 1998 |
| Charles Cooper Conservation, Restoration & Heritage Consultation Limited | Professional & scientific | 2024 |
| Chase Maddox Ltd | Construction | 2005 |
| Chemical Controls Limited | Extraterritorial | 1983 |
| Cherry Boom Hire Limited | Administrative & support | 2023 |
| Chevron Capital Limited | Construction | 2024 |
| Cheyneys Lodge Limited | Professional & scientific | 2022 |
| CHG Transport and Lifting Limited | Transport & logistics | 2023 |
| Chill Factor Limited | Other services | 2000 |
| Christie Close Limited | Households | 2022 |
| Christopher Vincent Ltd | Manufacturing | 2022 |
| Cibo (Stortford) Ltd | Hospitality | 2013 |
| Class One Finishers Ltd | Administrative & support | 2016 |
| Clearview HR Ltd | Professional & scientific | 2011 |
| Climate Hire Group Events Limited | Construction | 2024 |
| Climate Hire Group Limited | Construction | 2023 |
| Competitive Tackle Limited | Wholesale & retail | 2021 |
| Computer Systems UK Ltd. | Manufacturing | 1988 |
| Connect Access Ltd | Construction | 2015 |
| Connect Hire Group Ltd | Construction | 2022 |
| Coralmead Solutions Ltd | Administrative & support | 2015 |
| Corfield Communications Limited | Professional & scientific | 2014 |
| Cornelius Group PLC | Wholesale & retail | 1985 |
| Costs - ADR Limited | Professional & scientific | 2015 |
| Covert Security Installations Ltd | Administrative & support | 2012 |
| Cowen Edutainment Ltd | Information & communication | 2015 |
| CPI International Limited | Wholesale & retail | 1998 |
| Cqhg Limited | Professional & scientific | 2011 |
| Creative Business Psychology Limited | Professional & scientific | 2010 |
| Creative Music Limited | Wholesale & retail | 2009 |
| Cricket View Management Limited | Households | 2020 |
| Crios Developments Limited | Real estate | 2021 |
| Cronus Construction Projects Limited | Real estate | 2022 |
| CSS Global Consulting Limited | Professional & scientific | 2010 |
| Cubic One Construction Ltd | Construction | 2019 |
| Cullen Investments Ltd | Financial services | 2022 |
| Cullen Utilities Limited | Construction | 2017 |
| Culturistics Ltd | Information & communication | 2019 |
| Cute Clothing Limited | Wholesale & retail | 2022 |
| Cygnet (Plant) Limited | Wholesale & retail | 2011 |
| Cygnet Property Investments Ltd | Real estate | 2019 |
| CZ & Sons Limited | Water & waste | 2025 |
| D Humphrey Holdings Limited | Financial services | 2025 |
| D Humphrey Limited | Professional & scientific | 2025 |
| D&A Employment Ltd | Extraterritorial | 2014 |
| D&A Training Limited | Transport & logistics | 2017 |
| D.J. Holmes Limited | Health & social care | 2002 |
| D.S. Lloyd Limited | Construction | 1994 |
| Danny Burgess Illustration Limited | Professional & scientific | 2012 |
| Darren Hogg Elec. Limited | Professional & scientific | 2019 |
| DAS Racing Limited | Arts & recreation | 2018 |
| Davison Group Limited | Construction | 2023 |
| Dbaoncall Limited | Information & communication | 2013 |
| DBC Projects UK Ltd | Construction | 2018 |
| Dcad Limited | Construction | 2003 |
| Deben Investments Limited | Real estate | 2010 |
| Dedun Properties Limited | Construction | 2025 |
| DEE Zammit Ltd | Wholesale & retail | 2011 |
| Deeprec.Ai Limited | Administrative & support | 2023 |
| Deepseas Limited | Manufacturing | 1987 |
| Define Land Ltd | Real estate | 2024 |
| Delegation of the Government of Catalonia to the United Kingdom Ltd | Professional & scientific | 2021 |
| Delta Polo Team Limited | Arts & recreation | 2023 |
| Delta Tango Limited | Professional & scientific | 2019 |
| Denmau Limited | Administrative & support | 2011 |
| Dervish Global Limited | Real estate | 2022 |
| Destino Ventures Limited | Professional & scientific | 2024 |
| Dexter Gibson Limited | Real estate | 2021 |
| Dextrous Cook Ltd | Hospitality | 2019 |
| Digiclear Hearing Aids Limited | Wholesale & retail | 2000 |
| Digital Gangsta Limited | Information & communication | 2020 |
| DLE Global Services Limited | Professional & scientific | 2024 |
| Dora London Limited | Real estate | 2024 |
| Dotmatics Limited | Information & communication | 2005 |
| Dove Agriculture (Eastern) Limited | Agriculture & fishing | 2014 |
| Dovetail Professional Services Ltd | Administrative & support | 2022 |
| DR Denim Limited | Wholesale & retail | 2025 |
| Dragonfly Lasercare Limited | Other services | 2025 |