| C R B C Limited | Administrative & support | 2003 |
| C Wilson Brickwork Limited | Construction | 2023 |
| C&T Property Maintenance Ltd | Construction | 2022 |
| C&T Prospects Ltd | Transport & logistics | 1994 |
| C. S. Peet Limited | Administrative & support | 2013 |
| C.D.P. Builders & Decorators Ltd | Construction | 2003 |
| C.Lamb Paving Ltd | Construction | 2015 |
| C.R.E.E.D Organisation Ltd | Other services | 2025 |
| C.W.E Developments Ltd | Construction | 2020 |
| C2L Support Services Ltd | Administrative & support | 2020 |
| CA Van DER Merwe Limited | Health & social care | 2020 |
| Cabadas Cooke Consultancy Ltd | Construction | 2025 |
| Cabane Official Ltd | Other services | 2024 |
| Cable Test Limited | Construction | 2003 |
| Cable Tracing Services Limited | Construction | 1996 |
| Cabletec Electrical Services Limited | Construction | 2007 |
| Cablewise Electrical Limited | Construction | 2005 |
| Cadarn Property Investments Limited | Construction | 2025 |
| Cadence Consulting Limited | Professional & scientific | 2022 |
| Cadogan Design Ltd | Manufacturing | 2026 |
| Cafe House 89 Limited | Hospitality | 2024 |
| Caffè Piccolo Limited | Hospitality | 2025 |
| Cagier Limited | Professional & scientific | 2021 |
| Cajj Limited | Professional & scientific | 2013 |
| Caldera Atlantic Group Limited | Administrative & support | 2019 |
| Call a CUT Ltd | Other services | 2021 |
| Callaghan Consulting Incorporated Ltd | Administrative & support | 2016 |
| Callow Quality Consulting Ltd | Professional & scientific | 2016 |
| Calna Limited | Hospitality | 2023 |
| CAM Property Investments Ltd | Real estate | 2007 |
| Camac Plumbing & Heating Limited | Construction | 2024 |
| Cambridge Road (RBK) LLP | | 2020 |
| Camden Development Partnership LLP | | 2021 |
| Camera & Lighting Services Limited | Information & communication | 2003 |
| Camera Truck Services TV & Film Ltd | Information & communication | 2019 |
| Campbell and Law Facilities Management LLP | | 2018 |
| Campbell Haig Ltd | Professional & scientific | 2011 |
| Campbell Sports Media Ltd | Professional & scientific | 2019 |
| Canbec Ltd | Real estate | 2019 |
| Candi London Ltd | Wholesale & retail | 2018 |
| Cantina Porthleven Ltd | Hospitality | 2022 |
| Canvas Nails Ltd | Other services | 2025 |
| Capalume Limited | Professional & scientific | 2026 |
| Capital Coin Machine Company Limited | Administrative & support | 2000 |
| Capital Commercial Brickwork Limited | Construction | 2022 |
| Capital Flooring Solutions Ltd | Construction | 2014 |
| Capital Glaziers UK Limited | Construction | 2012 |
| Capitalpro Agency Limited | Administrative & support | 2023 |
| Car Buyer 24 UK Ltd | Wholesale & retail | 2009 |
| Cara Caring Services Limited | Health & social care | 2017 |
| Cara Green Limited | Health & social care | 2018 |
| Caravel Search Ltd. | Administrative & support | 2010 |
| Carbine Club London Limited | Other services | 2013 |
| Carcierge Travel Limited | Administrative & support | 2025 |
| Cardamom POD Ltd | Manufacturing | 2024 |
| Care & Medical Limited | Administrative & support | 2013 |
| Care Clinical Ltd | Health & social care | 2023 |
| Care Nest Holding Ltd | Financial services | 2026 |
| Care Search Ltd | Health & social care | 2015 |
| Carelia Court Management Company Limited | Households | 2006 |
| Carelink Services Ltd | Administrative & support | 2020 |
| Caremax Homecare Services Limited | Health & social care | 2014 |
| Caremax Property Services Limited | Real estate | 2022 |
| Cargolog Ltd | Administrative & support | 2019 |
| Carisma Trading Limited | Wholesale & retail | 1996 |
| Carpenter's Daughter Limited | Arts & recreation | 2024 |
| Carpet and Flooring Gallery Ltd. | Wholesale & retail | 2018 |
| Carpet Designs 2 Ltd | Administrative & support | 2023 |
| Carpet Designs Limited | Manufacturing | 1968 |
| Carriedale Ltd. | Administrative & support | 2020 |
| Carr’S Catering Limited | Hospitality | 2025 |
| Carter & Franklin Homes Ltd | Real estate | 2022 |
| Carter & Shayler Interiors Ltd | Construction | 2024 |
| Carter Cabs Limited | Administrative & support | 2015 |
| Carteret Limited | Transport & logistics | 2016 |
| Carters Painting and Decorating Limited | Construction | 2019 |
| Carver Industries Limited | Construction | 2021 |
| CAS Plumbing and Heating Services Ltd | Construction | 2022 |
| Casa Velenza Ltd | Manufacturing | 2026 |
| Casemixsolutions Limited | Health & social care | 2013 |
| Casey and Jamie Limited | Administrative & support | 2017 |
| Cask & Curious Ltd | Wholesale & retail | 2017 |
| Cass Consulting Limited | Information & communication | 2022 |
| Cass's Kitchen Ltd | Hospitality | 2026 |
| Cassidy Farms Ltd | Agriculture & fishing | 2008 |
| Cassidy Livestock Ltd | Agriculture & fishing | 2008 |
| Cast Contracts Ltd | Construction | 2022 |
| Cast Fit OUT Ltd | Construction | 2020 |
| Cast Flooring Limited | Construction | 2019 |
| Cast Furniture Ltd | Manufacturing | 2020 |
| Cast Group Services Ltd | Financial services | 2021 |
| Cast Labs Ltd | Construction | 2024 |
| Castle Exterior Services Limited | Construction | 2009 |
| Castleton Assets Ltd | Real estate | 2019 |
| Castleton Homes Ltd | Real estate | 2018 |
| Casual Finance Ltd | Extraterritorial | 2012 |
| Catalpa Financial Planning Ltd | Financial services | 2013 |
| Catalpa Limited | Financial services | 2013 |
| Catalyst IQ Ltd | Professional & scientific | 2023 |
| Catena Studios Ltd | Manufacturing | 2017 |