| Corporate Treasury Services Ltd | Professional & scientific | 2014 |
| Corra Wellness Ltd | Manufacturing | 2026 |
| Cortexflow Ltd | Information & communication | 2026 |
| Cosmic Health Ltd | Information & communication | 2023 |
| Cosmicminster Limited | Real estate | 1983 |
| Cost Sure Estimating Limited | Professional & scientific | 2020 |
| Costastrans Ltd | Transport & logistics | 2020 |
| Cottage Estate Management (Croxley) Limited | Real estate | 1993 |
| Count House Ltd | Professional & scientific | 2026 |
| Counties Construction Ltd | Construction | 2021 |
| Country Life Homes South East Ltd | Construction | 2016 |
| Cowley Road Property Ltd | Real estate | 2021 |
| COX Costello South Limited | Professional & scientific | 2016 |
| CP & Sons Property Limited | Real estate | 2022 |
| CP Group Holdings Limited | Financial services | 2026 |
| CPA Investments Limited | Professional & scientific | 2018 |
| Cpic Limited | Professional & scientific | 2025 |
| CPN Property Limited | Real estate | 2015 |
| Craft Locals Limited | Wholesale & retail | 2017 |
| Craftmyspace Interiors Ltd | Manufacturing | 2024 |
| Craigweil Consulting Limited | Professional & scientific | 2019 |
| Craven and Gould Consulting Limited | Professional & scientific | 2018 |
| Crazy Tails Academy Ltd | Education | 2023 |
| CRC Construction Ltd | Construction | 2018 |
| Crestview Developments Ltd | Real estate | 2023 |
| CRH Commerce Limited | Wholesale & retail | 2024 |
| Crisp Cloud Consulting Ltd | Professional & scientific | 2014 |
| Cristea Building Ltd | Construction | 2006 |
| Cristea Property Solutions Ltd | Real estate | 2026 |
| Cristian's Cleaning Services Ltd | Administrative & support | 2020 |
| CRM Business Consulting Services Ltd | Information & communication | 2013 |
| Crmed Limited | Administrative & support | 2016 |
| Crocus Books and Gifts Ltd | Wholesale & retail | 2025 |
| Crofton-Sleigh Research Limited | Professional & scientific | 1997 |
| Crosby Green Management Company Limited | Real estate | 2003 |
| Crossboundary UK Ltd | Administrative & support | 2019 |
| Crossways (UK) Ltd | Hospitality | 2011 |
| Crownhorse Stays Ltd | Hospitality | 2026 |
| Croxfest CIC | Arts & recreation | 2023 |
| Croxley Cars Limited | Transport & logistics | 2020 |
| Croxley Dental Clinic Ltd | Health & social care | 2025 |
| Croxley Hardware Limited | Wholesale & retail | 2022 |
| Croxley Home Physio Ltd | Other services | 2023 |
| Croxley Physio Academy Limited | Health & social care | 2026 |
| Croxley Pizza Ltd | Hospitality | 2021 |
| Croxley Plumbing Supplies Limited | Wholesale & retail | 2011 |
| Croxleytreecare Limited | Agriculture & fishing | 2016 |
| Croxteth Hall Limited | Professional & scientific | 2020 |
| Croí Pilates Ltd | Arts & recreation | 2024 |
| Crumpets Veterinary Services Ltd | Professional & scientific | 2009 |
| Crumpler Studio Ltd | Professional & scientific | 2023 |
| Crunch District Ltd | Hospitality | 2026 |
| Cryan Construction Services Limited | Construction | 2014 |
| Crystal Mobile Homes Ltd | Real estate | 2025 |
| CSK Therapeutics Ltd | Health & social care | 2014 |
| CSM Consultancy Limited | Real estate | 2015 |
| CT Invest Property Solutions Ltd | Real estate | 2021 |
| Cuckoo Castle Ltd | Real estate | 2023 |
| Cullen Design and Innovation Ltd | Manufacturing | 2026 |
| Cult 53 Limited | Wholesale & retail | 2025 |
| Cunningham Property Estate Ltd | Real estate | 2022 |
| Cuppa CUP Ltd | Hospitality | 2025 |
| Cura Automotive Ltd | Transport & logistics | 2026 |
| Curious Thinkers Ltd | Professional & scientific | 2020 |
| Currency Connect Limited | Financial services | 2023 |
| CV Consulting Services Ltd | Professional & scientific | 2026 |
| Cwil Limited | Real estate | 2024 |
| Cwmsafe Limited | Real estate | 1994 |
| Cyberbtx Ltd | Information & communication | 2022 |
| Cyril Smith (Fencing) Limited | Construction | 1977 |
| Cyril Smith (Holdings) Limited | Other services | 1994 |
| Czarrne Owce International Ltd | Transport & logistics | 2020 |
| D & S Jackson Ltd | Information & communication | 2008 |
| D G Cabling Limited | Information & communication | 2014 |
| D G Roofing Limited | Construction | 2003 |
| D Grand Homes Ltd | Construction | 2015 |
| D Nagle Mechanical Limited | Construction | 2017 |
| D Sills Services Ltd | Arts & recreation | 2024 |
| D Siyani Consultancy Ltd | Information & communication | 2014 |
| D&D Homeimprovements and Flooring Ltd | Construction | 2020 |
| D.A. Mcleod Property Consultants Limited | Professional & scientific | 2002 |
| D.K. Engineering (Blue Chip) Limited | Wholesale & retail | 2015 |
| D.K. Engineering (Holdings) Limited | Financial services | 2015 |
| D.K. Engineering (Servicing) Limited | Wholesale & retail | 2015 |
| D.K. Engineering (Storage Services) Limited | Transport & logistics | 2015 |
| D.K. Engineering Acquisition Consultancy Limited | Wholesale & retail | 2015 |
| D.K. Engineering Limited | Extraterritorial | 1988 |
| D.P.H. London Limited | Construction | 2015 |
| DAE Services Limited | Professional & scientific | 2017 |
| Daedalus Group Ltd | Information & communication | 2024 |
| Daedalus Property Ltd | Real estate | 2022 |
| Daily Drives Motors Ltd | Wholesale & retail | 2024 |
| Daley Decorator Limited | Construction | 2016 |
| Dalton's Late Modern Company Limited | Hospitality | 2017 |
| Damillion Company Ltd | Administrative & support | 2025 |
| Damp Monitor Ltd | Professional & scientific | 2024 |
| Danatics UK Limited | Information & communication | 2014 |
| Dancers Boutique Limited | Wholesale & retail | 2025 |
| Danek Ltd | Other services | 2018 |
| Danes Educational Trust Trading Limited | Education | 2016 |