| Casametro Limited | Professional & scientific | 2012 |
| Casemore Consulting Limited | Professional & scientific | 2025 |
| Casesnappy Ltd | Information & communication | 2023 |
| Cash Free Community Ltd | Administrative & support | 2019 |
| Cash-Score London Limited | Other services | 2014 |
| Castlefield Limited | Real estate | 2010 |
| Catalyst Change Group Ltd | Information & communication | 2025 |
| Catapult Analytics Ltd | Financial services | 2021 |
| Catch 22 Jams CIC | Arts & recreation | 2023 |
| Catering Linen Hire Ltd | Administrative & support | 2018 |
| Catherine Baxter Coaching Limited | Professional & scientific | 2023 |
| Cavalier Inns Limited | Hospitality | 2004 |
| Cayton Construction Limited | Construction | 2018 |
| Cbtr Optical Ltd | Wholesale & retail | 2023 |
| CC Fashion Ltd | Wholesale & retail | 2017 |
| CDT Automotive Holdings Ltd | Administrative & support | 2024 |
| CEB Property Consulting Limited | Real estate | 2020 |
| Cehb Limited | Professional & scientific | 2017 |
| CEK Management Ltd | Professional & scientific | 2013 |
| Celtic Fireworks Ltd | Wholesale & retail | 2004 |
| Centrepiece International Ltd | Wholesale & retail | 2019 |
| Centrix-Europe Ltd | Manufacturing | 2014 |
| Cero Cabs Limited | Professional & scientific | 1960 |
| Cetromed Limited | Administrative & support | 2014 |
| CGA Project Services Ltd | Professional & scientific | 2012 |
| Chacombe Place Ltd | Households | 1998 |
| Chad Engineering UK Limited | Manufacturing | 2001 |
| Chalfont Consulting Actuaries LLP | | 2023 |
| Chalfont Taxis Limited | Transport & logistics | 2011 |
| Chalford Estate Freehold Company Limited | Real estate | 2003 |
| Chamberlain & Chamberlain Ltd | Administrative & support | 2017 |
| Chameleon Search Limited | Professional & scientific | 2009 |
| Changecenter Limited | Information & communication | 2003 |
| Chaos Software Limited | Other services | 2026 |
| Character Enterprises Limited | | 1986 |
| Charlie Fennell Music Ltd | Information & communication | 2025 |
| Chartered Facilities Management Limited | Administrative & support | 2011 |
| Chartridge Developments Limited | Construction | 1998 |
| Chartridge PLC | Construction | 2000 |
| Chartwell Gate Residents Management Limited | Households | 1984 |
| Chasehart Limited | Construction | 1986 |
| Chaucer Homes Family Property LLP | | 2020 |
| Chaucer Homes Group Limited | Construction | 2015 |
| Chaucer Homes Investments Limited | Real estate | 2021 |
| Chelstorm Limited | Hospitality | 2019 |
| Cherry Blossom Homes Limited | Real estate | 2023 |
| Cherry Drive Residents Association Limited | Households | 1997 |
| Cherry Drive Woodland Limited | Households | 2014 |
| Child Wise Limited | Professional & scientific | 1988 |
| Chiltern Corporation Limited | Professional & scientific | 2023 |
| Chiltern Corporation Wealth Limited | Financial services | 2024 |
| Chiltern Energy Group Ltd | Construction | 2026 |
| Chiltern Hills Services Ltd | Construction | 2025 |
| Chiltern Music Therapy Community Interest Company | Education | 2011 |
| Chiltern Relocation Ltd | Administrative & support | 2008 |
| Chiltern Security Ltd | Construction | 2025 |
| Chiltern Trust Corporation Limited | Professional & scientific | 2024 |
| Chiltern Wills LLP | | 2021 |
| Chiltern Yard (Penn) Management Company Limited | Households | 2021 |
| China Diner Beaconsfield Ltd | Hospitality | 2025 |
| Chirnside Properties Limited | Real estate | 1951 |
| Chiswell Pools Limited | Construction | 1981 |
| Cholbury Place Management Company Limited | Households | 2023 |
| Chorlton Plaza Limited | Construction | 2021 |
| Churchill College Oxford Ltd | Education | 2007 |
| Cine Galaxy Limited | Information & communication | 2026 |
| City and Thames Services Limited | Professional & scientific | 2010 |
| Citystorm Limited | Hospitality | 2023 |
| CJ4 Limited | Professional & scientific | 2009 |
| Claims Handling AS a Service Limited | Financial services | 2020 |
| Clare Blampied Ltd | Hospitality | 2025 |
| Clare Family Office Ltd | Real estate | 2024 |
| Claridge Property Developments Ltd | Professional & scientific | 2014 |
| Clark Associates Isle of Wight LLP | | 2011 |
| Claude Bernard (UK) | Wholesale & retail | 2015 |
| Claude Bernard Watches Ltd | Wholesale & retail | 2017 |
| Clear Drains (U.K.) Limited | Construction | 1972 |
| Clearbrook Associates Ltd | Information & communication | 2015 |
| Clearcrest Windscreens Limited | Manufacturing | 1979 |
| Clearway Plumbing & Drains Ltd | Water & waste | 2015 |
| Clementine Blakemore Limited | Professional & scientific | 2016 |
| Clever Homes and Properties Ltd | Construction | 2024 |
| Clever Homes Limited | Construction | 2024 |
| Clinton & Fufu Limited | Real estate | 2017 |
| Clive Stevenson Limited | Education | 2012 |
| Clos Maggiore Restaurant Holdings Limited | Hospitality | 2026 |
| Cloud Tank Group Ltd | Information & communication | 2022 |
| Clths Limited | Real estate | 2024 |
| CMG Finishes Ltd | Construction | 2019 |
| Cntnr Partners Limited | Wholesale & retail | 2021 |
| CO-CRE8 Systems Limited | Wholesale & retail | 2019 |
| Coach the Difference Ltd | Professional & scientific | 2021 |
| Coaching Intelligence Systems Ltd | Information & communication | 2016 |
| Cobro Investments Limited | Financial services | 2018 |
| Cobud Consulting Limited | Professional & scientific | 2021 |
| Colgaz Limited | Hospitality | 2016 |
| Collection Developments Limited | Construction | 2015 |
| Collegium Investments LLP | | 2016 |
| Collingwood Nominees Limited | Financial services | 2014 |
| Comet Tankers Limited | Extraterritorial | 2003 |