| Byron Mansions Management Limited | Households | 1990 |
| C & G GAS and Heating Limited | Construction | 2012 |
| C Daws Sprinklers Ltd | Construction | 2012 |
| C J Graphic Installations Ltd | Other services | 2014 |
| C K Carpenters (Essex) Limited | Manufacturing | 2019 |
| C M R Systems Limited | Professional & scientific | 1999 |
| C S Wren Properties UK Ltd. | Real estate | 2017 |
| C Wilson Limited | Transport & logistics | 2012 |
| C&B Consultancy Services Limited | Administrative & support | 2022 |
| C. Percy Limited | Wholesale & retail | 1968 |
| C.A.W. Building Services Limited | Construction | 2014 |
| C.S.A Contractors Ltd | Construction | 2024 |
| C.W. Grain Limited | Wholesale & retail | 1982 |
| C100 Bespoke Fitted Furniture Ltd | Construction | 2026 |
| Cafe & Bistro 206 Ltd | Hospitality | 2024 |
| Cambridge CC Limited | Administrative & support | 2023 |
| Campbell’S Safety Solutions Limited | Health & social care | 2026 |
| Canary Photobooths' Ltd | Professional & scientific | 2023 |
| CAP Contracts Ltd | Construction | 2007 |
| Capital Cues Limited | Arts & recreation | 2006 |
| Capital Paving and Landscapes Ltd. | Administrative & support | 2015 |
| Capitol Digital Ltd | Manufacturing | 2010 |
| Cardamon Cottage Limited | Real estate | 2025 |
| Care & Comfort Products Limited | Manufacturing | 2004 |
| Care Plus Investments Limited | Professional & scientific | 2019 |
| Carecraft Limited | Administrative & support | 2009 |
| Carnella Limited | Information & communication | 2005 |
| Carpets Direct UK Limited | Wholesale & retail | 1997 |
| Carr & Sons Ltd | Construction | 2020 |
| Carrington B S Ltd | Construction | 2008 |
| Cars 4 YOU Direct Limited | Wholesale & retail | 2022 |
| Cars International Heritage Limited | Manufacturing | 2016 |
| Carter of London Construction Limited | Construction | 2022 |
| Casa Surface Design Ltd | Construction | 2024 |
| Casacourt Ltd | Financial services | 2023 |
| Casino Hair Limited | Other services | 2021 |
| Castle Construction & Sons Ltd | Construction | 2010 |
| Castle Hopefield Limited | Information & communication | 2006 |
| Castle View and Bayside Heights Limited | Real estate | 2021 |
| Castledon Ltd | Professional & scientific | 1997 |
| Castlepoint Medical Services Ltd | Health & social care | 2014 |
| Caststone Direct Limited | Manufacturing | 2018 |
| Casus Underwriting Limited | Financial services | 2023 |
| Catalytic Solutions Limited | Professional & scientific | 2018 |
| CB Solar Consulting Limited | Professional & scientific | 2026 |
| Cbase NET Ltd | Information & communication | 2014 |
| CBL Developments Limited | Real estate | 2019 |
| CBP Book Hub Limited | Professional & scientific | 2005 |
| CBP Book Shop Limited | Professional & scientific | 2005 |
| Cece Creations & Events Ltd | Wholesale & retail | 2025 |
| CED Limited | Wholesale & retail | 1959 |
| CED Natural Stone Limited | Other services | 2012 |
| CED Stone Group Limited | Real estate | 1933 |
| CED Stone Limited | Extraterritorial | 2014 |
| Centerline Tooling Limited | Manufacturing | 2019 |
| Central Collective Group Ltd | Wholesale & retail | 2024 |
| Central Lithographic Printing Company Limited | Manufacturing | 1996 |
| Centurion Recruitment Limited | Administrative & support | 2018 |
| CEP Engineering Limited | Construction | 2010 |
| Cert Business Solutions Ltd | Administrative & support | 2018 |
| Cerulean City Collectables Ltd | Wholesale & retail | 2021 |
| CG Accounting & Tax Limited | Professional & scientific | 2003 |
| Chadwick Lodge Limited | Health & social care | 2016 |
| Chafer Products Ltd | Wholesale & retail | 2023 |
| Chalkwell Construction Limited | Construction | 2021 |
| Chambers Group Holdings Limited | Financial services | 2020 |
| Change a PAW Life Rescue CIC | Agriculture & fishing | 2021 |
| Change Delta Limited | Information & communication | 2011 |
| Charles Birch (Essex) Limited | Professional & scientific | 1974 |
| Charles Birch (Sussex) Limited | Professional & scientific | 1946 |
| Charterhouse Building Solutions Limited | Professional & scientific | 2017 |
| Charterhouse Shipbroking Company Ltd. | Transport & logistics | 1993 |
| Chase Bereavement Services Ltd | Administrative & support | 2021 |
| Chauffeur Chauffeur London Ltd | Transport & logistics | 2018 |
| Chayes Consultancy Services Limited | Professional & scientific | 2018 |
| Chelcol Limited | Hospitality | 2017 |
| Cheltenham House RTM Company Limited | Households | 2008 |
| Cherontech Ltd | Information & communication | 2020 |
| Cherry Garden | Professional & scientific | 2018 |
| Cherry Orchard GAS Ltd | Wholesale & retail | 2024 |
| Cherry Pips Day Nursery Ltd | Administrative & support | 2018 |
| Cherry Waffle Investments Ltd | Real estate | 2026 |
| Chesterton Property Developments Limited | Real estate | 1988 |
| Cheviot Pension Services Limited | Administrative & support | 1995 |
| Cheviot Trustees Limited | Administrative & support | 2005 |
| Chigwellhouse Construction Ltd | Construction | 2023 |
| Chris Allnutt and Co Management Limited | Real estate | 2005 |
| Chris Woodman Photography Ltd | Professional & scientific | 2022 |
| Christie Services Ltd | Arts & recreation | 2023 |
| Christmas Trees Ltd | Wholesale & retail | 1998 |
| Chrycraft Limited | Health & social care | 2001 |
| Citrine Wealth Ltd | Professional & scientific | 2021 |
| City Elite Transaction Services Ltd | Administrative & support | 2024 |
| City Stream Media Ltd | Information & communication | 2021 |
| Civil Engineering Developments Limited | Extraterritorial | 1988 |
| Clark Aviation Solutions Ltd | Professional & scientific | 2016 |
| Clark Crewe Therapy Limited | Health & social care | 2025 |
| Claw Stock Ltd | Wholesale & retail | 2023 |
| Clayswell Court Management Company Limited | Real estate | 2003 |
| Clean Air Cars Limited | Transport & logistics | 2018 |