| Celtic Coffee Limited | Hospitality | 2024 |
| Celtic Compliance Ltd | Administrative & support | 2022 |
| Celtic Country Sports Ltd | Arts & recreation | 2019 |
| Celtic Electrical Services Limited | Construction | 2022 |
| Celtic HGV Training Ltd | Education | 2022 |
| Celtic Teachers Ltd | Professional & scientific | 2007 |
| Celtic Vehicle Maintenance Services Limited | Wholesale & retail | 2019 |
| Celtic Windscreens & Glazing LLP | | 2025 |
| Celtic Wool Insulation Limited | Real estate | 1999 |
| Celticqs Ltd | Professional & scientific | 2025 |
| CEM Programme Management Consultants Limited | Professional & scientific | 2019 |
| Cenin APV Ltd | Energy | 2022 |
| Cenin Gwynt Limited | Energy | 2018 |
| Cenin Holdings Ltd | Professional & scientific | 2010 |
| Cenin Limited | Manufacturing | 2005 |
| Cenin Property Limited | Real estate | 2018 |
| Centregreat Construction Limited | Extraterritorial | 2006 |
| Centregreat Engineering Limited | Construction | 2012 |
| Centregreat Fabrication Limited | Manufacturing | 2020 |
| Centregreat Group Limited | Extraterritorial | 2017 |
| Centregreat Lighting Limited | Extraterritorial | 2004 |
| Centregreat Limited | Construction | 1974 |
| Centregreat Property Limited | Financial services | 2017 |
| Centregreat Rail Limited | Construction | 2009 |
| Centregreat Trade Limited | Financial services | 2017 |
| Cerebral Consulting Limited | Professional & scientific | 2018 |
| Cerys' Closet Ltd | Wholesale & retail | 2017 |
| CFG Aviation Limited | Manufacturing | 2013 |
| CH Environmental Services Limited | Professional & scientific | 2017 |
| Challoch Energy Limited | Professional & scientific | 2012 |
| Chameleon Brands Limited | Professional & scientific | 2020 |
| Chan's Properties Limited | Real estate | 2007 |
| Chandni Optics Limited | Wholesale & retail | 2024 |
| Channel Electrix Ltd | Administrative & support | 2025 |
| Channel Marine Limited | Construction | 2023 |
| Chapel Road Investments Limited | Financial services | 2026 |
| Charge ME Ltd | Construction | 2014 |
| Charisma Turkish Barber Ltd | Other services | 2023 |
| Charles Dale Productions Ltd | Information & communication | 2018 |
| Charnwood Park Management (Bridgend) Limited | Administrative & support | 2006 |
| Charnwood Park Management Unit 1 (Bridgend) Limited | Real estate | 2007 |
| Charterwood Resource Management Limited | Financial services | 2006 |
| Chateau Dessert Group Ltd | Hospitality | 2024 |
| Chaudry Stores Ltd | Wholesale & retail | 2013 |
| Chauvel’S Detailing Ltd | Wholesale & retail | 2025 |
| Cheeky Baby Tees Ltd | Wholesale & retail | 2012 |
| Cheeky Chick Boutique Limited | Wholesale & retail | 2025 |
| Cheque OUT Ltd | Wholesale & retail | 2024 |
| Cherish Venues Ltd | Real estate | 2024 |
| Cherubs Cred Limited | Wholesale & retail | 2006 |
| Cheryl Bass Ltd | Administrative & support | 2024 |
| Chestnut Films Limited | Information & communication | 2012 |
| CHI Education Limited | Education | 2023 |
| Chi-Luxe Clean Limited | Administrative & support | 2025 |
| Chic Events and Catering Ltd | Hospitality | 2024 |
| Chic Party Boutique Ltd | Wholesale & retail | 2025 |
| Chich PUB Co Ltd | Hospitality | 2023 |
| Chichester Hospitality Group Limited | Hospitality | 2025 |
| Childsplay Industrial Control Ltd. | Information & communication | 1994 |
| Childsplay Surf Gear Limited | Wholesale & retail | 2012 |
| Chislett Contracting Services Limited | Professional & scientific | 2022 |
| CHL Overseas Limited | Administrative & support | 2025 |
| Chris Malcolm Limited | Information & communication | 2001 |
| Chris Morris Construction Services Limited | Construction | 2016 |
| Chris Packer Limited | Real estate | 2003 |
| Chris Waterworth Architects Limited | Professional & scientific | 2012 |
| Christal Clear Cleaning Ltd | Administrative & support | 2016 |
| Christie-Tyler Ltd | Extraterritorial | 2022 |
| Christine a Baldwin Ltd | Professional & scientific | 2025 |
| Christopher LEE Catering Ltd | Hospitality | 2006 |
| Churchgrove Limited | | 1970 |
| Cibernetica Limited | Administrative & support | 2019 |
| CII Construction Limited | Construction | 2023 |
| Cinderella Cardiff Limited | Other services | 2016 |
| Cinnamon Spice Ltd | Hospitality | 2018 |
| Cipspeed Ltd | Transport & logistics | 2019 |
| Circuit D K Ltd | Information & communication | 2016 |
| Circuit Electronic Services Limited | Manufacturing | 2016 |
| Cityrats Limited | Information & communication | 2007 |
| CJC Construction&Landscaping Ltd | Construction | 2025 |
| CJM Quality Consultancy Ltd | Professional & scientific | 2015 |
| CJP Sales (Holdings) Limited | Other services | 2023 |
| Ckew Ltd | Other services | 2025 |
| CL & SS Property Maintenance Ltd | Administrative & support | 2020 |
| Cl&Ss Developments & Driveways Ltd | Construction | 2025 |
| Clack's Discount Carpets & Furniture Ltd | Wholesale & retail | 2015 |
| Clad-Scape Ltd | Construction | 2024 |
| Claire Lucas Business Services Ltd | Professional & scientific | 2025 |
| Claremont Care Home (Bridgend) Limited | Health & social care | 2019 |
| Clariteos Ltd | Professional & scientific | 2025 |
| Clarke's Surveying Services Ltd | Construction | 1997 |
| Clarkson Marine Limited | Manufacturing | 2010 |
| Classic Floor Care Limited | Other services | 2011 |
| Clay Shaw Thomas Limited | Professional & scientific | 2005 |
| Clayton Power Systems UK Ltd | Wholesale & retail | 2022 |
| Cldo Marketing Ltd | Professional & scientific | 2025 |
| Clean Air Monitoring Solutions Limited | Manufacturing | 2023 |
| Cleanpitt Ltd | Financial services | 2020 |
| Cleantrax Limited | Administrative & support | 2020 |
| Clear Accountants Limited | Professional & scientific | 2011 |