| CPI - Chelmsford Limited | Real estate | 2024 |
| CPI - Croydon Brighton Road Limited | Real estate | 2024 |
| CPI - Croydon Purley Way Limited | Real estate | 2024 |
| CPI - Edinburgh Limited | Real estate | 2024 |
| CPI - Hatfield Mosquito Way Limited | Real estate | 2024 |
| CPI - Hatfield Plot 5610 Limited | Real estate | 2024 |
| CPI - Maidstone Limited | Real estate | 2024 |
| CPI - Oldham Limited | Real estate | 2024 |
| CPI - Preston Limited | Real estate | 2024 |
| CPI - Solihull Balsall Common Limited | Real estate | 2024 |
| CPI - Swindon Limited | Real estate | 2024 |
| CPI - Thanet (Ramsgate) Limited | Real estate | 2024 |
| CPI - Tunbridge Wells Limited | Real estate | 2024 |
| CPI - Warrington Limited | Real estate | 2024 |
| CPI - Wootton Bassett Limited | Real estate | 2024 |
| Craig and Sons Ltd | Other services | 2020 |
| Craig Hi-Fi Limited | Wholesale & retail | 1976 |
| Crave Collectif Ltd | Hospitality | 2026 |
| Create Great Events Ltd | Education | 2025 |
| Creative Audio-Visual Solutions Limited | Construction | 2004 |
| Cresta Motors Limited | Wholesale & retail | 2003 |
| Cris Logistics Ltd | Transport & logistics | 2026 |
| Cristi Rotrans Limited | Transport & logistics | 2022 |
| Crixus (London) Ltd | Financial services | 2012 |
| Crixus Property Ltd | Real estate | 2020 |
| Crockers Experience Limited | Hospitality | 2022 |
| Crohn's & Colitis UK Ltd | Health & social care | 2006 |
| Crop Connect Limited | Wholesale & retail | 2025 |
| Crossfit Hackney Wick Limited | Arts & recreation | 2020 |
| Crspy Ltd | Wholesale & retail | 2026 |
| Crystal Bright Cleaning Ltd | Administrative & support | 2025 |
| Csecure Networks Ltd | Information & communication | 2006 |
| Ctani Services Ltd | Information & communication | 2019 |
| Cube Property Development Ltd | Construction | 2022 |
| Cucumber Fields Limited | Other services | 2020 |
| Cullen Travel Limited | Extraterritorial | 2017 |
| CURE360 Ltd | Other services | 2019 |
| Curzon Point Limited | Real estate | 2023 |
| Cuverly AI Ltd | Information & communication | 2025 |
| CV Driver Services Ltd | Transport & logistics | 2014 |
| CV37 Developments Ltd | Construction | 2026 |
| CVA Interbuild Ltd | Construction | 2015 |
| CVM Design Consulting Ltd | Professional & scientific | 2023 |
| CVS Businesses Ltd | Professional & scientific | 2016 |
| CW Carpets Limited | Construction | 1998 |
| Cy&C Investment Limited | Real estate | 2019 |
| Cyan Five Limited | Professional & scientific | 2020 |
| Cyclop Transport Limited | Transport & logistics | 2025 |
| Cyder Digital Limited | Manufacturing | 2025 |
| Cygnet Technologies Ltd | Transport & logistics | 2015 |
| D & N Construction Services Limited | Construction | 2017 |
| D & Q Signs & Shopfitting Limited | Construction | 2002 |
| D & U Construction Ltd | Administrative & support | 2015 |
| D F Keane Building Maintenance Limited | Construction | 2014 |
| D F Keane New Homes Limited | Construction | 2015 |
| D M Perera Limited | Professional & scientific | 2017 |
| D Mackay Farming Company Unlimited | Agriculture & fishing | 2012 |
| D&A HAS Ltd | Construction | 2012 |
| D&A Xhelili Ltd | Construction | 2021 |
| D&C Consultants and Plantscapes Limited | Professional & scientific | 2006 |
| D&D Speed Limited | Transport & logistics | 2017 |
| D&F Logistics Limited | Wholesale & retail | 2017 |
| D&G Dezdari Limited | Construction | 2024 |
| D&G Properties London Limited | Construction | 2019 |
| D&J Hicks Limited | Financial services | 2019 |
| D&M Facilities Ltd | Administrative & support | 2021 |
| D&N Herts Couriers Ltd | Transport & logistics | 2021 |
| D&R Painting & Decorating Ltd | Construction | 2019 |
| D'Art Decorators Ltd | Construction | 2021 |
| D. F. Keane Management Services Limited | Professional & scientific | 1997 |
| D.A.P. Services Limited | Real estate | 1970 |
| D.F. Keane Limited | Construction | 1993 |
| D.F. Keane Plant and Transport Limited | Administrative & support | 2014 |
| D2 International (Europe) Ltd | Manufacturing | 2019 |
| DAA Consultants Ltd. | Professional & scientific | 2003 |
| Daerin Trading Limited | Hospitality | 2023 |
| Dagenham 9 Limited | Households | 2026 |
| Daily Wellness Limited | Manufacturing | 2024 |
| Daio Ltd | Professional & scientific | 2013 |
| Daiwater Investment Limited | Financial services | 2017 |
| Dalkey Developments Ltd | Construction | 2012 |
| Danfield Properties Limited | Real estate | 1994 |
| Daniel Clive Boucher Ltd | Professional & scientific | 2025 |
| Daniel Field Clinic Limited | Other services | 2018 |
| Daniel Field Consultant Ltd | Other services | 2012 |
| Daniel Field Franchising Ltd | Administrative & support | 2020 |
| Daniel Field Products Limited | Other services | 2012 |
| Dans Tyres Limited | Real estate | 2003 |
| Dany & SON Limited | Construction | 2019 |
| Dany Digitals Ltd | Information & communication | 2026 |
| Danyrom Ltd | Transport & logistics | 2019 |
| Dara Facades Limited | Construction | 2021 |
| Darklayer Tech Ltd | Information & communication | 2026 |
| Darlish Ltd | Manufacturing | 2015 |
| Darren J Westmore Ltd | Information & communication | 2023 |
| Darsa Alternative Gopro Ltd | Construction | 2023 |
| DAS Küche Limited | Construction | 2024 |
| DAS Tackle Ltd | Wholesale & retail | 2020 |
| DAS Video Ltd | Information & communication | 2011 |
| Daseo Properties Ltd | Real estate | 2019 |