| Chesterton Mews Management Company Limited | Households | 2024 |
| Chewberri Limited | Professional & scientific | 2022 |
| Cheyney Design & Development Ltd. | Professional & scientific | 2001 |
| Cheyney Estates 2 Limited | Real estate | 2017 |
| Cheyney Research Limited | Professional & scientific | 2013 |
| Chez Burton Letchworth Ltd | Hospitality | 2023 |
| Chez Burton Limited | Hospitality | 2021 |
| Childlessness Overcome Through Surrogacy Limited | Other services | 2019 |
| Chilford Hall Farm Limited | Extraterritorial | 1987 |
| Chilford Hundred Limited | | 1993 |
| Chishanu Pro Clean Ltd | Administrative & support | 2026 |
| Chiswick END Management Company Limited | Households | 2020 |
| Chloe Nails Bar Ltd | Other services | 2026 |
| Chorus Communications Limited | Administrative & support | 2023 |
| Chris Dinsdale Consulting Limited | Professional & scientific | 2024 |
| Chrishall Management Company Limited | Households | 1987 |
| Christ's Hope International UK | Health & social care | 2003 |
| Christian Spence Ltd | Professional & scientific | 2019 |
| Christopher Alma Christopher Limited | Real estate | 2007 |
| Christopher Digby Homes Ltd | Construction | 2020 |
| Christopher Grace Consultants Limited | Professional & scientific | 2006 |
| Chukka & Punch Ltd | Manufacturing | 2024 |
| Cinesystem Ltd | Information & communication | 2014 |
| Ciprian 85 Ltd | Manufacturing | 2025 |
| Citrine Wellness Ltd | Professional & scientific | 2019 |
| Claimsline UK Limited | Extraterritorial | 2013 |
| Claire Engelmann Limited | Professional & scientific | 2012 |
| Clam Records Limited | Information & communication | 2022 |
| Clare Joghee, Organisation Development Ltd | Professional & scientific | 2017 |
| Clarkspropertyinvestments Ltd | Real estate | 2023 |
| Clarvo Trades Ltd | Wholesale & retail | 2024 |
| Class 100 Limited | Professional & scientific | 1992 |
| Class Clowns Ltd | Education | 2025 |
| Class Cuts Ltd | Other services | 2009 |
| Claxton Manor Estate Limited | Real estate | 2010 |
| Claydon Family Holdings Limited | Real estate | 2015 |
| Claydon Hawke Limited | Education | 2012 |
| Clean Fleet Limited | Administrative & support | 2019 |
| Clean, by Richard Ltd | Administrative & support | 2025 |
| Cleaning Repairs & Maintenance Ltd | Construction | 2013 |
| Clear Farms Limited | Extraterritorial | 1982 |
| Cleasby Property Limited | Real estate | 2019 |
| Clerk's Compliance Limited | Professional & scientific | 2025 |
| Cleverly Creative Group Ltd | Professional & scientific | 2019 |
| Clewlow Consulting Limited | Professional & scientific | 2009 |
| Cloisters Management Company Limited(The) | Administrative & support | 1985 |
| Clopton Park Estate Limited | Real estate | 2011 |
| Cloud Fish Limited | Information & communication | 2015 |
| Clover Freerange Eggs Ltd | Wholesale & retail | 2017 |
| Cluroe & Hall Ltd | Health & social care | 2016 |
| CMF Capital Ltd | Financial services | 2014 |
| CMF Renewables Ltd | Financial services | 2019 |
| CMP Resolutions Holdings Limited | Financial services | 2024 |
| CMP Resolutions Holdings Trustee Limited | Extraterritorial | 2024 |
| Cnmc Properties Limited | Real estate | 2012 |
| Coachmaker Mews Limited | Households | 2001 |
| Coastal Key Properties Limited | Real estate | 2026 |
| Cobalt Engineering Ltd | Professional & scientific | 2022 |
| Cobalt Fabrications Limited | Manufacturing | 2024 |
| Cobcrete Limited | Manufacturing | 1994 |
| Cocktail Box Limited | Hospitality | 2009 |
| Cocoroot Ltd | Wholesale & retail | 2025 |
| Cogitat Ltd | Information & communication | 2020 |
| Cokenach Limited | Agriculture & fishing | 2002 |
| Coldharbour Developments Limited | Construction | 2010 |
| Colebrook Healthcare Limited | Health & social care | 2008 |
| Colina Greenway Limited | Professional & scientific | 2011 |
| Collins Farming and Forestry Services Limited | Agriculture & fishing | 2008 |
| Comfycare Limited | Professional & scientific | 2005 |
| Complete Bricks Limited | Construction | 2003 |
| Complete Industrial and Commercial Services Limited | Administrative & support | 1989 |
| Compliance Expert Group Limited | Wholesale & retail | 2024 |
| Composition Creative Consultancy Ltd | Administrative & support | 2025 |
| Computiv Limited | Information & communication | 2006 |
| Conacu Voyages Limited | Administrative & support | 2025 |
| Conference Systems Limited | Extraterritorial | 2007 |
| Conflict Management Plus Limited | Professional & scientific | 1999 |
| Connect Services (2000) Limited | Construction | 2000 |
| Consuela Serv Ltd | Administrative & support | 2015 |
| Contoura Collective Ltd | Wholesale & retail | 2020 |
| Contrails.Org (UK) Limited | Other services | 2025 |
| Conway House Freehold Limited | Real estate | 2011 |
| Coolbox (Pacific) | | 1998 |
| Coolbox (South-East Asia) | | 1998 |
| Coolmain Consulting Ltd | Professional & scientific | 2024 |
| Cooper Radioisotope Solutions Ltd | Professional & scientific | 2022 |
| Cope Productions Ltd | Information & communication | 2014 |
| Copperfox Communications Limited | Professional & scientific | 2016 |
| Copperhead Electrical Services Ltd | Construction | 2024 |
| Copston Associates Limited | Wholesale & retail | 1984 |
| COR Fortium Ltd | Administrative & support | 2019 |
| Corbyn House Management Company Limited | Households | 1981 |
| Core Edge Facilities Management Ltd | Administrative & support | 2014 |
| Core Edge Living Ltd | Construction | 2026 |
| Cortex Technology Group Ltd | Financial services | 2025 |
| Cosmopolites Limited | Administrative & support | 2014 |
| Cotential Limited | Health & social care | 2021 |
| Cotswolds Hidden GEM Limited | Hospitality | 2023 |
| Coulier Creatures FX Limited | Information & communication | 2008 |
| Country Commercials Limited | Wholesale & retail | 2020 |