| CJM Lettings Limited | Real estate | 2020 |
| CJM Property Ltd | Real estate | 2015 |
| CJN Business Services Limited | Professional & scientific | 2025 |
| CJP Corporation Ltd | Financial services | 2019 |
| CJS Electrical (Wales) Ltd | Construction | 2005 |
| CJS Specialist Cleaning Ltd | Administrative & support | 2026 |
| CJS Wicks Properties Ltd | Real estate | 2021 |
| CJT Industries Ltd | Professional & scientific | 2023 |
| CJURES3XY Ltd. | Wholesale & retail | 2024 |
| CJW Droylsden Limited | Hospitality | 2018 |
| CK & WT Land Limited | Real estate | 2025 |
| CK & WT Properties Limited | Real estate | 2018 |
| CK and WT Llangennech Ltd | Real estate | 2026 |
| CK Audio Systems Ltd | Administrative & support | 2016 |
| CK Bourne Ltd | Hospitality | 2015 |
| CK Canton Traygap Ltd | Hospitality | 2026 |
| CK Cities Limited | Wholesale & retail | 2023 |
| CK Communications Holdings Limited | Financial services | 2025 |
| CK Creative Solutions Ltd | Arts & recreation | 2021 |
| CKC Property Development Limited | Real estate | 2004 |
| CKL Assets Limited | Real estate | 2023 |
| CKL Build Group Ltd | Construction | 2016 |
| CKM Health Consulting Ltd | Professional & scientific | 2022 |
| Cktsafe Electric Co., Ltd | Professional & scientific | 2020 |
| CL (Financial Services) Limited | Financial services | 2005 |
| CL Amusements Services Limited | Arts & recreation | 2022 |
| CL Global Solution Ltd | Professional & scientific | 2025 |
| CL Letting Company Ltd | Real estate | 2020 |
| CL75 Hair Team Limited | Other services | 2018 |
| CLA Fabrication 31 Ltd | Administrative & support | 2018 |
| Cladd Contractors Ltd | Construction | 2016 |
| Cladding & Construction Limited | Construction | 2016 |
| Cladding Systems UK Ltd | Construction | 2014 |
| Claffy Sport and Entertainment Limited | Administrative & support | 2016 |
| Claim Line 365 Ltd | Professional & scientific | 2015 |
| Claire Charlton Consultancy Limited | Professional & scientific | 2025 |
| Claire Hill Designs Limited | Wholesale & retail | 2014 |
| Claire Roberts Limited | Professional & scientific | 2018 |
| Clairis Saas Ltd | Information & communication | 2025 |
| Clalfx Limited | Other services | 2025 |
| Clan Owners Club | Other services | 2024 |
| Clany's Ltd | Wholesale & retail | 2024 |
| Clara Finch Ltd | Wholesale & retail | 2024 |
| Clarabella Consulting Limited | Information & communication | 2022 |
| Clare Dodd Homes Ltd | Real estate | 2024 |
| Clare Food (Cardiff) Limited | Wholesale & retail | 2005 |
| Clare Food (Newport) Limited | Professional & scientific | 2003 |
| Clare Food Superstore Limited | Wholesale & retail | 2011 |
| Clare Property Group Ltd | Real estate | 2022 |
| Clare Street Management Company Limited | Households | 2003 |
| Claremont Homes (Reading) Limited | Real estate | 2018 |
| Claremont Property Management Ltd | Other services | 2019 |
| Clarence Mews Management (Cardiff) Limited | Households | 2004 |
| Clares Hair Salon Ltd | Other services | 2024 |
| Clarify Technology Ltd | Wholesale & retail | 2026 |
| Clarionmill Limited | Professional & scientific | 2015 |
| Clarity Building Consultants Ltd | Professional & scientific | 2019 |
| Clarity Construction Group Limited | Construction | 2026 |
| Clarity Contractors Employment Services Ltd | Professional & scientific | 2025 |
| Clarity Data Solutions Ltd | Information & communication | 2025 |
| Clarity Foundry Ltd | Administrative & support | 2025 |
| Clarity Glass Repairs Limited | Construction | 2019 |
| Clarity Tax & Ledger Limited | Professional & scientific | 2025 |
| Clarity Vault Ltd | Professional & scientific | 2025 |
| Clarivise Ltd | Administrative & support | 2016 |
| Clarivo Ltd | Administrative & support | 2025 |
| Clark Logistics Ltd | Transport & logistics | 2019 |
| Clark's Holdings Limited | Extraterritorial | 2015 |
| Clark's Original Pies Limited | Extraterritorial | 2015 |
| Clarke Matthews Limited | Professional & scientific | 1991 |
| Clarke Property Trading Ltd | Real estate | 2023 |
| Clarks Premier Ltd | Wholesale & retail | 2017 |
| Clarkson Carpentry Services Ltd | Manufacturing | 2018 |
| Clarkson FOX Limited | Wholesale & retail | 2019 |
| Clarkster Services Limited | Professional & scientific | 2023 |
| Classic Agro Group Ltd | Agriculture & fishing | 2025 |
| Classic AS Ltd | Hospitality | 2024 |
| Classic Lines (Castle Cary) Ltd | Other services | 2002 |
| Classic Mystery Shopper Ltd | Professional & scientific | 2019 |
| Classic Noble Ltd | Wholesale & retail | 2025 |
| Classic Ventilations Limited | Construction | 2017 |
| Claude Investments Ltd | Real estate | 2022 |
| Claude Road Management Limited | Households | 1991 |
| Claudia Sterrer-Pichler | Professional & scientific | 2023 |
| Clauwsnik Limited | Transport & logistics | 2018 |
| Claycanopy Ltd | Wholesale & retail | 2025 |
| Claykicker Productions Limited | Information & communication | 2018 |
| Claymore Estate Planning Limited | Professional & scientific | 2017 |
| Claymore Land & Properties Limited | Real estate | 2018 |
| Claymore Wealth Limited | Financial services | 2011 |
| Clayson Ecom Limited | Wholesale & retail | 2025 |
| Clbhairlashology Ltd | Wholesale & retail | 2021 |
| CLC Construction Consultants Limited | Professional & scientific | 2002 |
| CLC Design Limited | Professional & scientific | 1986 |
| Clcmgardening CYF | Wholesale & retail | 2025 |
| CLD Facilities Services Ltd | Administrative & support | 2021 |
| Clean & Gleam Ltd. | Administrative & support | 2018 |
| Clean & Go Ltd | Administrative & support | 2020 |
| Clean & Maintain 1 Limited | Administrative & support | 2025 |
| Clean 4U Services Ltd | Administrative & support | 2022 |