| Chansom Estates Limited | Real estate | 2012 |
| Chaotically Neat Ltd | Wholesale & retail | 2023 |
| Chapel House Residents Management Company (Hyde Heath) Limited | Households | 1991 |
| Chappell Group Limited | Construction | 2021 |
| Chappell Property Investments Ltd | Real estate | 2022 |
| Chappell Property Services Limited | Construction | 2016 |
| Charles House UK Ltd | Hospitality | 2025 |
| Charles Platel & Partners (Solicitors) Limited | Professional & scientific | 1995 |
| Charlesgate Construction Limited | Construction | 2006 |
| Charlesgate Homes (Burghfield) Limited | Construction | 2016 |
| Charlesgate Homes Limited | Construction | 2006 |
| Charlie Brown Plumbing Ltd | Construction | 2024 |
| Chartan Limited | Professional & scientific | 2019 |
| Chartoria Ltd | Construction | 2016 |
| Chase & Sons Limited | Professional & scientific | 2005 |
| Chase Protective Coatings Limited | Manufacturing | 2007 |
| Chats AI Limited | Information & communication | 2025 |
| Chauffeur Reading Limited | Transport & logistics | 2021 |
| Cheap Street Management Company Ltd | Households | 2026 |
| Cheeky Monkey Videos Ltd | Information & communication | 2024 |
| Chequer Court RTM Company Limited | Households | 2023 |
| Cherry Garden Music LLP | | 2024 |
| Cherry White Limited | Information & communication | 2009 |
| Cherry White Properties Ltd | Real estate | 2021 |
| Cherryliz Limited | Education | 2015 |
| Cheshire Consultants Limited | Other services | 2011 |
| Chesterman Properties Ltd | Real estate | 2016 |
| Chesters Walk Ltd | Households | 2013 |
| Chestnut Place Limited | Households | 2005 |
| Chevron Software Limited | Information & communication | 2008 |
| Child Health International | Health & social care | 1992 |
| Chill Baby Ltd | Wholesale & retail | 2013 |
| Chiltern Rise Property Group Limited | Real estate | 2025 |
| Chimariko Limited | Professional & scientific | 2011 |
| Chime Coffee Ltd | Hospitality | 2025 |
| Chisel and Cloth Limited | Manufacturing | 2016 |
| Chloe Jade Story Ltd | Information & communication | 2023 |
| Choice Accountants Limited | Professional & scientific | 2008 |
| Choice Business Services (UK) Limited | Professional & scientific | 2015 |
| Cholsey Meadows Management Company Limited | Households | 2011 |
| Chow LIE Limited | Wholesale & retail | 2025 |
| Chris Curtis Software Services Ltd | Professional & scientific | 2018 |
| Chris Hemmings Limited | Administrative & support | 2021 |
| Christy Court (Tadley) Management Company Limited | Households | 1989 |
| Church View (Bracknell) Management Company Limited | Households | 2001 |
| Churchill Roofers Ltd | Construction | 2024 |
| Churton Studio Ltd | Professional & scientific | 2020 |
| CIA Cyber Ltd | Information & communication | 2025 |
| Cilla O Donnell Limited | Health & social care | 2011 |
| Cineglow Lighting Ltd | Arts & recreation | 2024 |
| Cinnamon Property Limited | Administrative & support | 2003 |
| Circle Clothing Company Ltd | Wholesale & retail | 2024 |
| Circuit Plating Equipment Limited | Wholesale & retail | 1971 |
| Citizen Watch United Kingdom, Ltd | Manufacturing | 2000 |
| Citnow Ltd | Extraterritorial | 2016 |
| Citnow Video Limited | Professional & scientific | 2015 |
| Citrine Diagnostics Limited | Health & social care | 2024 |
| Citroemech Limited | Wholesale & retail | 2005 |
| Citroemech Properties Limited | Real estate | 2003 |
| City of Light Media Services Group Ltd | Information & communication | 2024 |
| City of Light Twickenham Film Studios Ltd | Information & communication | 2024 |
| City Windows (Berkshire) Limited | Construction | 2011 |
| CJE Scenery Limited | Information & communication | 2025 |
| CJH Maintenance Ltd | Administrative & support | 2025 |
| CJP Consulting Ltd | Professional & scientific | 2019 |
| CKB Real Estate Ltd | Real estate | 2020 |
| CKR Catering Ltd | Hospitality | 2021 |
| Claire Brooks Ltd | Professional & scientific | 2016 |
| Claire Myers Hygiene Ltd | Health & social care | 2013 |
| Clarence Court (Wendover) Management Company Ltd | Households | 2018 |
| Clarence Mews Residents Company Limited | Households | 2007 |
| Claritas Accountancy Limited | Professional & scientific | 2007 |
| Claritas HR & Training Limited | Administrative & support | 2017 |
| Claritas VA Limited | Administrative & support | 2018 |
| Clarityblend Ltd | Wholesale & retail | 2020 |
| Clark & Poole Limited | Administrative & support | 2009 |
| Clasp (Caring, Listening and Supporting Partnership) | Health & social care | 2006 |
| Classicsoft Ltd | Real estate | 2011 |
| Claudia S Rodriguez Consulting Limited | Professional & scientific | 2018 |
| Clay Pictures Ltd | Information & communication | 2026 |
| Clayton Limited | Construction | 2001 |
| Clean and Secure Code Ltd | Information & communication | 2024 |
| Clean MK Ltd | Administrative & support | 2023 |
| Clean My Office (Home Counties) Ltd | Other services | 2025 |
| Clean My Office (London) Ltd | Other services | 2025 |
| Clean My Office(West Berkshire) Limited | Other services | 2012 |
| Cleaning and Hygiene Suppliers' Association | Other services | 1969 |
| Cleaning and Maintenance (South) Ltd | Administrative & support | 2013 |
| Cleaning Facilities Ltd | Administrative & support | 2022 |
| Clearbrand Limited | Professional & scientific | 2015 |
| Cleareye Communications Limited | Professional & scientific | 2018 |
| Clearlake Holdings Limited | Financial services | 2023 |
| Clearsight Property Services Limited | Administrative & support | 2025 |
| Clearsoft Technologies Limited | Information & communication | 2011 |
| Cleartone Group Limited | Information & communication | 2003 |
| Cleaver Property Management Limited | Real estate | 2008 |
| Cleaver Property Services Limited | Real estate | 2012 |
| Clements & COX Ltd | Information & communication | 2025 |
| Clevedon Lodge Management Company Limited | Households | 1988 |
| Clever Cabbage Ltd | Professional & scientific | 2019 |