| Cartify Premium Ltd | Wholesale & retail | 2026 |
| Cartykm Ltd | Real estate | 2022 |
| Carvaan Trading Ltd | Wholesale & retail | 2010 |
| Carvill Creative Limited | Professional & scientific | 2005 |
| Carvill Design Ltd | Professional & scientific | 2025 |
| Carz Tech Ltd | Wholesale & retail | 2026 |
| Carza Motor Group Ltd | Wholesale & retail | 2021 |
| Carza UK Ltd | Wholesale & retail | 2025 |
| CAS Contracts Ltd | Administrative & support | 2010 |
| CAS Mortgages Ltd | Financial services | 2020 |
| Casa DI Lusso Care Limited | Health & social care | 2020 |
| Casacosta Ltd | Hospitality | 2020 |
| Casakey Construction Ltd | Construction | 2024 |
| Casakey Limited | Real estate | 2020 |
| Cashflow Accounts Ltd | Other services | 2018 |
| Caspian Industrial Services Ltd | Construction | 2012 |
| Castellum Security Group Ltd | Administrative & support | 2025 |
| Castle Fine Foods Ltd | Wholesale & retail | 2024 |
| Castle Homes (Hillingdon) Limited | Construction | 2022 |
| Castle Homes (London) Limited | Construction | 2013 |
| Castle Homes Ruislip Limited | Real estate | 2016 |
| Castle IT Consultancy Limited | Real estate | 2015 |
| Castle Manufacturing Limited | Manufacturing | 2020 |
| Castle Quality Consulting Limited | Professional & scientific | 2025 |
| Castle Sharif Limited | Real estate | 2016 |
| Castle Transport (London) Limited | Transport & logistics | 2024 |
| Castle View Roofing Solutions Limited | Construction | 2025 |
| Castleview Commercial Estates Limited | Real estate | 2015 |
| Castleview Homes Limited | Real estate | 2019 |
| Castleview Motors Ltd | Wholesale & retail | 2025 |
| Castleview School | Education | 2012 |
| Catalea Gabriela Ltd | Administrative & support | 2025 |
| Cataleya Design Ltd | Construction | 2017 |
| Catalin Hodorogea Limited | Other services | 2018 |
| Catchify Limited | Wholesale & retail | 2024 |
| Caterfood (South West) Limited | Wholesale & retail | 1972 |
| Caterfood Holdings Limited | Financial services | 2008 |
| Catering 786 Ltd | Hospitality | 2011 |
| Catering Sparky Ltd | Manufacturing | 2023 |
| Catherinememorialce Ltd | Health & social care | 2025 |
| Catonine Ltd | Information & communication | 2015 |
| Catriona Hassall Limited | Health & social care | 2012 |
| Cattle Grid Westend Ltd | | 2008 |
| Caultex Enterprises Limited | Professional & scientific | 2014 |
| Caultex Technology Limited | Information & communication | 2000 |
| Cavalieri 1973 Ltd | Wholesale & retail | 2025 |
| Cavanis Limited | Hospitality | 2026 |
| Cavendish Resources Limited | Wholesale & retail | 1998 |
| Caversham Coachworks (Slough) Limited | Wholesale & retail | 2006 |
| Cavs Enterprises Ltd | Health & social care | 2022 |
| Cavs Guardian Limited | Manufacturing | 2022 |
| Cawnpore Limited | Wholesale & retail | 2018 |
| Cayman Capital Group Ltd | Real estate | 2020 |
| Cazemo Ltd | Information & communication | 2013 |
| Cbamrah Ltd | Health & social care | 2016 |
| CBC Ciaran Beary Consulting Limited | Professional & scientific | 2002 |
| Cbre Group Ltd | Wholesale & retail | 2025 |
| CC Blue Trading Ltd | Wholesale & retail | 2021 |
| CC7 Management Limited | Professional & scientific | 2021 |
| CCA Accountants Limited | Professional & scientific | 2012 |
| CCB Consultancy Ltd | Information & communication | 2017 |
| Ccents Limited | Real estate | 2021 |
| CCG Nhomes HO Limited | Health & social care | 2019 |
| CCG Opco Limited | Health & social care | 2024 |
| CCG Payroll Limited | Administrative & support | 2015 |
| Ccgrass (UK ) Co., Limited | Wholesale & retail | 2020 |
| Cchr Solutions Ltd | Professional & scientific | 2014 |
| CCM NH Limited | Health & social care | 1984 |
| CCS Homecare Services Ltd | Other services | 2007 |
| CCS Property Services (UK) Limited | Administrative & support | 2007 |
| CD Consultants Ltd | Other services | 2026 |
| Cdde Holdings Limited | Real estate | 2025 |
| Cdkm Consulting Limited | Information & communication | 2014 |
| CDM Glazing Ltd | Construction | 2023 |
| Ceaciea Enterprises Ltd | Wholesale & retail | 2025 |
| Ceasar Property Ltd | Real estate | 2022 |
| Cebu Builders Ltd | Construction | 2024 |
| Cecil Keynes Limited | Real estate | 2010 |
| Cedar Lodge Care Limited | Health & social care | 2020 |
| Cedar Way Property Management Ltd | Real estate | 2017 |
| Cedar-Saiyam Limited | Health & social care | 2019 |
| Cedarloom Limited | Wholesale & retail | 2026 |
| Cedars Care Home (Southend-On-Sea) Limited | Health & social care | 2003 |
| Cedars Nominee Co 1 Limited | Extraterritorial | 2015 |
| Cedars Nominee Co 2 Limited | Extraterritorial | 2015 |
| Ceefam Europe Ltd | Health & social care | 2024 |
| Ceejay Markings Ltd | Construction | 2013 |
| Ceffyl Limited | Professional & scientific | 2024 |
| Celestia Consulting Limited | Wholesale & retail | 2014 |
| Celestrix Ltd | Information & communication | 2014 |
| Celextino Int'Nl Ltd | Health & social care | 2015 |
| Cell Phone Repair & Accessories Shop Ltd | Wholesale & retail | 2023 |
| Cellmark Services Ltd | Wholesale & retail | 1961 |
| Cellora Supplements Ltd | Wholesale & retail | 2025 |
| Celltastic Limited | Professional & scientific | 2018 |
| Cellular Communications (GB) Limited | Wholesale & retail | 2003 |
| Centara Management Ltd | Real estate | 2026 |
| Centara Properties Group Ltd | Real estate | 2023 |
| Centaurus IT Limited | Information & communication | 2012 |
| Centennial One Limited | Construction | 2025 |