| Cozdan Construction Ltd | Construction | 2016 |
| Cozens Partners Limited | Real estate | 1946 |
| Cozy Dream Stays UK Ltd | Real estate | 2024 |
| CP Infotech Limited | Information & communication | 2015 |
| CPD (Europe) Ltd | Professional & scientific | 1998 |
| CPF Leisure Limited | Arts & recreation | 2014 |
| CPH Construction & Development Ltd | Construction | 2006 |
| CPL Manufacturing Ltd | Manufacturing | 2016 |
| Craft Nurseries Limited | Administrative & support | 2006 |
| Craft Windows Limited | Construction | 2000 |
| Craftsman Caravan Company Limited | Real estate | 1988 |
| Craftsman Glass Limited | Manufacturing | 2007 |
| Craig Boyle Project Services Ltd | Professional & scientific | 2026 |
| Craig Hancock Limited | Arts & recreation | 2003 |
| Crammonds Designs Limited | Wholesale & retail | 1994 |
| Cranbrook Basements Limited | Construction | 1995 |
| Cranbrook Wines Limited | Other services | 2002 |
| Cranmer House Limited | Administrative & support | 1999 |
| Create a Call Ltd | Administrative & support | 2019 |
| Creating Care Choices Limited | Health & social care | 2000 |
| Creating Memories Limited | Administrative & support | 2002 |
| Creative Fit Limited | Construction | 2002 |
| Creative Reasoning Enterprises Limited | Other services | 2024 |
| Credit-Aio Ltd | Professional & scientific | 2025 |
| Creed & Co Estates Ltd | Real estate | 2018 |
| Creed Properties Limited | Real estate | 1993 |
| Creektown Solutions Limited | Information & communication | 2007 |
| Crep Therapy Ltd | Wholesale & retail | 2025 |
| Crescent Management (Billericay) Limited | Real estate | 1993 |
| Crest Adventure Ltd | Administrative & support | 2026 |
| Crest Wood Commerce & Finance Limited | Wholesale & retail | 2026 |
| Crestdata I.T. Limited | Information & communication | 1999 |
| Crester Services Limited | Administrative & support | 2004 |
| Crestford Ltd | Wholesale & retail | 2025 |
| Cresthall Ventures Limited | Arts & recreation | 2003 |
| Crestwood Investments Limited | Hospitality | 1984 |
| Crezions Ltd | Wholesale & retail | 2023 |
| Crfp Ltd | Households | 2024 |
| Cribnook Homes Limited | Real estate | 2016 |
| Crid Accountancy Services Ltd | Professional & scientific | 2022 |
| Crimson & Scarlet Bespoke Decorators Ltd | Construction | 2015 |
| Cristel Communications Limited | Professional & scientific | 2006 |
| Crittall Holdings Limited | Construction | 1995 |
| Crittall Windows Limited | Manufacturing | 1924 |
| Crocs Ltd | Administrative & support | 1998 |
| Cromwell Estates (UK) Limited | Other services | 2002 |
| Cronus Media Limited | Professional & scientific | 2025 |
| Crosby Associates General Builders Ltd | Construction | 2002 |
| Cross Channel Trade Ltd | Wholesale & retail | 2023 |
| Crossroads Tendring & Colchester Ltd | Health & social care | 2004 |
| Crossways Garage (Halstead) Limited | Wholesale & retail | 2000 |
| Crow Civil Limited | Construction | 2005 |
| Crow Property Ltd | Construction | 1981 |
| Crown Advisory Services Ltd | Professional & scientific | 2025 |
| Crown Developments Limited | Construction | 1987 |
| Crown Estates and Properties Limited | Households | 1996 |
| Crown Estates Management Limited | Extraterritorial | 2004 |
| Crown Property Ventures Ltd | Real estate | 2019 |
| Crown Quality Kitchens Limited | | 1999 |
| Crown Scaffolding Services Limited | Construction | 2005 |
| Crown Ventilation (Colchester) Limited | Construction | 2003 |
| Crowne-Spencer Limited | Wholesale & retail | 2005 |
| Crowstone Estates Limited | Real estate | 1993 |
| CRUISE247 Ltd | Information & communication | 2024 |
| Crumbz Cafe Limited | Hospitality | 2019 |
| Crushpeach Ltd | Wholesale & retail | 2024 |
| Crystal Girl Rocks Ltd | Wholesale & retail | 2024 |
| Crystal Investments Holdings Limited | Manufacturing | 2021 |
| Crystal Lagun Limited | Information & communication | 1999 |
| CS Global Consultants Ltd | Professional & scientific | 2024 |
| Csch Ltd | Professional & scientific | 2024 |
| CSG Flower Ltd | Real estate | 2023 |
| CSL Racing Limited | Construction | 2007 |
| Csoft Limited | Information & communication | 1989 |
| CTE Limited | Other services | 2005 |
| Cube Squared IT Consultancy Ltd | Information & communication | 2021 |
| Cubitt Taverns Limited | Hospitality | 1995 |
| Cuero by HAC Limited | Wholesale & retail | 2026 |
| Cumberland Construction Co Limited | Construction | 2007 |
| Cumberland Court (Woodford Green) Management Company Limited | Administrative & support | 1988 |
| Cumberland Fit OUT UK Limited | Construction | 2007 |
| Cumberland Joinery Limited | Construction | 2007 |
| Cumberland Road (Baltic Wharf) Management Company Limited | Households | 2026 |
| Curaso Limited | Health & social care | 2025 |
| Curchi Interiors Ltd | Construction | 2025 |
| Curran Developments Ltd | Real estate | 2020 |
| Curry Cottage Crouch Ltd | Hospitality | 2025 |
| Curry Sultan (Hutton) Limited | Hospitality | 2020 |
| Cursor&Co Ltd | Wholesale & retail | 2026 |
| Curtis Civil Engineering Consultants Limited | Construction | 2014 |
| Curvemind Creations Limited | Information & communication | 2025 |
| Curwen Print Study Centre Limited | Arts & recreation | 1994 |
| CUT Through Media Ltd | Information & communication | 2018 |
| Cuton Residents Company Limited | Households | 2002 |
| Cutting Edge Tooling Limited | Wholesale & retail | 2004 |
| CV Jamaica Ltd | Administrative & support | 2025 |
| CV1 Displays Limited | Wholesale & retail | 2004 |
| CVR Property Maintenance Ltd | Administrative & support | 2023 |
| CW London Clock Ltd | Administrative & support | 2022 |
| Cwills Solutions Ltd | Wholesale & retail | 2024 |