| Creedcarpentry Limited | Construction | 2023 |
| Creedesign Ltd | Arts & recreation | 2015 |
| Cregagh Properties LLP | | 2012 |
| Cregmore Investments | Professional & scientific | 2022 |
| Crescent Executive Administration Ltd. | Administrative & support | 2017 |
| Crestfield Properties (35A Farncombe) LLP | | 2016 |
| Cretabyte Limited | Information & communication | 2017 |
| Crisitech Ltd | Other services | 2024 |
| Cristian Arciri Ltd | Wholesale & retail | 2021 |
| Criterion Software Limited | Information & communication | 2001 |
| Critical Systems Ltd | Professional & scientific | 2009 |
| Croatian Supplementary School London C.I.C. | Education | 2022 |
| Crofters Residents Company Limited | Households | 1983 |
| Crofton Manor Management Company Limited | Real estate | 2007 |
| Crosley Estates Limited | Real estate | 2006 |
| Cross Farm Projects Ltd | Hospitality | 2024 |
| Cross Keys Energy Limited | Mining & quarrying | 2017 |
| Cross Lanes Residents Association Limited | Households | 1975 |
| Crosse & Makewell Limited | Professional & scientific | 2019 |
| Crossways Media Ltd | Information & communication | 2023 |
| Crouch Energy Consulting Limited | Professional & scientific | 2006 |
| Crowd Connected Limited | Information & communication | 2013 |
| Crowes Associates Limited | Real estate | 2002 |
| Crowes Property Surveys Ltd | Professional & scientific | 2018 |
| Crowland Consulting Ltd | Administrative & support | 2024 |
| Crown Heights Management Limited | Households | 1991 |
| Crown Sterling Ltd | Professional & scientific | 2024 |
| Crown Valley Consulting Ltd | Construction | 2011 |
| Crownbridge Ventures Limited | Wholesale & retail | 2025 |
| Crownstone Property Ltd | Real estate | 2025 |
| Crownvalley Interiors Ltd | Other services | 2021 |
| Crownwood Estates (East Grinstead Land) Limited | Construction | 2009 |
| Crownwood Estates (Farnham) Limited | Construction | 2008 |
| Crownwood Estates (Wadhurst) Limited | Construction | 2010 |
| Crownwood Estates Limited | Construction | 1987 |
| Crownwood Securities Limited | Construction | 2005 |
| Crowther Capital Solutions Ltd | Professional & scientific | 2025 |
| Cruisegold Limited | Professional & scientific | 2007 |
| Crunch Mode Computer Consultants Limited | Information & communication | 1990 |
| Crunchpoint Limited | Professional & scientific | 2008 |
| Cruz the Juice Ltd | Hospitality | 2002 |
| CRW Guildford Limited | Extraterritorial | 2014 |
| Cryo Consultancy UK Ltd | Administrative & support | 2021 |
| Cryotag Limited | Wholesale & retail | 2016 |
| CS Full House Services Ltd | Construction | 2024 |
| CSB Luxe Ride Ltd | Transport & logistics | 2025 |
| CSB Stoneworks Ltd | Construction | 2018 |
| CSC Autos Ltd | Wholesale & retail | 2018 |
| CSG Corporation Ltd | Real estate | 2022 |
| CSH Contractors Ltd | Construction | 2022 |
| CT (IOW) Holdings Ltd | Financial services | 2019 |
| CT (IOW) Ltd | Construction | 2019 |
| CT Composites (UK) Limited | Manufacturing | 2001 |
| Ctrl-Alt-Del IT Ltd | Information & communication | 2007 |
| CU Holdings Ltd | Information & communication | 2021 |
| Cube Chase Ltd | Financial services | 2022 |
| Cube Green Energy (Spain) Limited | Financial services | 2023 |
| Cube Green Energy Holdings Limited | Financial services | 2021 |
| Cube Green Energy Limited | Financial services | 2021 |
| Cube Property Maintenance Limited | Construction | 2021 |
| Cubeflag Limited | Wholesale & retail | 2023 |
| Cubelets Digital Ltd | Information & communication | 2013 |
| Cubow Limited | | 1971 |
| CUC Ltd | Information & communication | 2022 |
| Cuchulain Film Partnership Limited | Information & communication | 2011 |
| CUE Finance Limited | Professional & scientific | 2023 |
| Culloma Technologies Limited | Information & communication | 2010 |
| Culture Content Agency Ltd | Professional & scientific | 2021 |
| Cummins Associates Limited | Professional & scientific | 1997 |
| Curiousx Limited | Wholesale & retail | 2025 |
| Currency Clear Limited | Financial services | 2019 |
| Cursor Controls Holdings Limited | Financial services | 2015 |
| Cursor Controls Limited | Manufacturing | 2000 |
| Custom Networks Limited | Information & communication | 1990 |
| Customdesigntechnologies Ltd | Manufacturing | 1986 |
| CUT Culture Barbers Ltd | Other services | 2026 |
| Cutler and Berry Limited | Manufacturing | 2022 |
| CVA Consulting Limited | Professional & scientific | 2011 |
| Cvht Enterprises Limited | Health & social care | 2000 |
| CW Aspen Developments Ltd | Financial services | 2025 |
| CW Nutrition Limited | Health & social care | 2015 |
| CWC PW Ltd | Professional & scientific | 2016 |
| CWS Advisers Ltd | Financial services | 2017 |
| CY Recruitment Limited | Administrative & support | 2021 |
| Cyber Security Risk Mitigation Services Limited | Information & communication | 2023 |
| Cyberpass Limited | Information & communication | 2019 |
| Cybertools Technology Ltd | Information & communication | 2017 |
| Cyclists Touring Club. | Other services | 1887 |
| Cyclists' Touring Club (Central) Limited | Other services | 1982 |
| Cyclists' Touring Club (Eastern) Limited | Other services | 1973 |
| Cyclists' Touring Club (Northern) Limited | Other services | 1973 |
| Cyclists' Touring Club (Southern) Limited | Other services | 1973 |
| Cyclists' Touring Club (Western) Limited | Other services | 1973 |
| Czech ENG Ltd | Administrative & support | 2023 |
| D & E Roberts Limited | Construction | 1992 |
| D & N Moore Property Ltd | Real estate | 2021 |
| D and D Grab Hire Ltd | Administrative & support | 2003 |
| D and G E Barnes Limited | Professional & scientific | 2011 |
| D Davidson Autotech Services Ltd | Professional & scientific | 2014 |
| D H Building Services Limited | Construction | 2002 |