| Cleaning Wings Ltd | Administrative & support | 2019 |
| Cleanluxe Ltd | Administrative & support | 2024 |
| Cleansy Co Ltd | Administrative & support | 2024 |
| Cleantec (EBT) Trustees Limited | Professional & scientific | 2021 |
| Cleantec (EOT) Trustees Limited | Professional & scientific | 2021 |
| Cleantec Services Limited | Administrative & support | 2001 |
| Cleaníge Ltd | Administrative & support | 2022 |
| Clear Property Investments Limited | Wholesale & retail | 2017 |
| Clearsay Limited | Information & communication | 2022 |
| Clearview Carp Tours Ltd | Hospitality | 2009 |
| Clemoo Integrated Services Limited | Construction | 2014 |
| Clerkenwell Consultancy Services Ltd | Administrative & support | 2017 |
| Clestar Limited | Construction | 2025 |
| Clever Accounts Ltd | Information & communication | 2007 |
| Clever Carpets & Flooring Limited | Wholesale & retail | 2018 |
| CLH Freehold Ltd | Households | 2018 |
| Click B International Trading Ltd | Wholesale & retail | 2025 |
| Click Connection Corporation Limited | Manufacturing | 2009 |
| Click Fragrance (UK) Limited | Extraterritorial | 2014 |
| Click Live Limited | Administrative & support | 2023 |
| Click Theory Limited | Information & communication | 2025 |
| Clientgate Solutions Ltd | Professional & scientific | 2025 |
| Cliff Edge Ltd | Real estate | 2020 |
| Cliffedge 10 Newquay Ltd | Construction | 2021 |
| Climatec Employees’ Trustees Limited | Administrative & support | 2021 |
| Climatec Limited | Manufacturing | 1993 |
| Climbing SC Ltd | Arts & recreation | 2026 |
| Clinical Consulting Limited | Health & social care | 2007 |
| Clinical Excellence UK Limited | Health & social care | 2019 |
| Clinical Media Ltd | Information & communication | 2017 |
| Clinical Review Associates Ltd | Professional & scientific | 2026 |
| Clinimarg Ltd | Wholesale & retail | 2013 |
| Clinisupplies GB Limited | Health & social care | 1990 |
| Clinisupplies Limited | Health & social care | 2000 |
| Clinsentry Investments Limited | Other services | 2023 |
| Clint Reddy Limited | Construction | 2013 |
| Clip Consultancy Limited | Information & communication | 1992 |
| Clisse Decor Limited | Construction | 2026 |
| Clitheroe Shah Consultancy Services Limited | Administrative & support | 2011 |
| Clive Newnham Consulting Limited | Professional & scientific | 2011 |
| Clive Street Ltd | Education | 2019 |
| Cloisters Court (Freehold) Ltd | Real estate | 2006 |
| Cloisters Properties Ltd | Real estate | 2012 |
| CLOSINGDOWN1 Ltd | Agriculture & fishing | 2018 |
| CLOSINGDOWN2 Ltd | Wholesale & retail | 2021 |
| Clothing by A1 Limited | Wholesale & retail | 2008 |
| Cloud Force Solutions Ltd | Professional & scientific | 2018 |
| Cloud Gems Limited | Information & communication | 2022 |
| Cloud Genius Training Ltd | Education | 2024 |
| Cloud IT Limited | Information & communication | 2009 |
| Cloud Nine Plus Ltd | Professional & scientific | 2020 |
| Cloud Wise Consultants Limited | Information & communication | 2024 |
| Cloudfinity Limited | Information & communication | 2019 |
| Cloudnex Limited | Information & communication | 2024 |
| Cloudnine PR Ltd | Professional & scientific | 2009 |
| Cloudone Consultancy Services Ltd | Professional & scientific | 2012 |
| Cloudresty Limited | Information & communication | 2021 |
| Cloudsec Consulting Limited | Information & communication | 2025 |
| Cloudsphere Ltd | Information & communication | 2026 |
| Cloudstone Property Ltd | Construction | 2021 |
| Clozesure Property Ltd | Real estate | 2012 |
| Club Fiit Ltd | Arts & recreation | 2022 |
| Club Mexicana Ltd | Hospitality | 2016 |
| Club World Limited | Hospitality | 2019 |
| Clyne Dynamics Ltd | Information & communication | 2019 |
| CM Construction London Ltd | Administrative & support | 2017 |
| CM Haulage Services Ltd | Transport & logistics | 2025 |
| CM Training Group Ltd | Professional & scientific | 2023 |
| CM9 Group Ltd | Real estate | 2020 |
| Cmad Consultants Ltd | Construction | 2015 |
| Cmagee Ltd | Information & communication | 2015 |
| Cman Group Ltd | Construction | 2021 |
| CMC Private Limited | Administrative & support | 2026 |
| CMC Utilities Ltd | Construction | 2020 |
| Cmcp Investments | Administrative & support | 2018 |
| CMG Group Limited | Construction | 2024 |
| CMI 2011 Ltd | Construction | 2011 |
| Cmkm Investments Limited | Households | 2025 |
| CML Food and Beverages Ltd | Hospitality | 2022 |
| CML Gourmet Market Limited | Manufacturing | 2022 |
| CML Projects Americas Limited | Information & communication | 2013 |
| CML Projects Broadcast Limited | Information & communication | 2013 |
| CML Projects Communications Limited | Information & communication | 2013 |
| CML Projects Digital Limited | Information & communication | 2013 |
| CML Projects Global Limited | Information & communication | 2013 |
| CML Projects International Limited | Information & communication | 2013 |
| CML Projects Latin America Limited | Information & communication | 2013 |
| CML Projects Technology Limited | Information & communication | 2013 |
| CML Projects Transmission Limited | Information & communication | 2013 |
| CML Trans Ltd | Transport & logistics | 2014 |
| Cmpm Services Limited | Information & communication | 2019 |
| CMR Corporation Limited | Administrative & support | 2010 |
| CMR Interiors Ltd | Construction | 2022 |
| CMR IT Limited | Information & communication | 2016 |
| CMR Recruitment Limited | Administrative & support | 2013 |
| Cmre Limited | Real estate | 2019 |
| CMS Capital Ltd | Financial services | 2025 |
| CMS Perio Ltd | Health & social care | 2022 |
| CNC Engineering Europe Ltd | Professional & scientific | 2009 |
| Cnote Healthtech Ltd | Information & communication | 2026 |