| CJM Property Holdings Ltd | Real estate | 2023 |
| CJP Holdings (Kent) Limited | Financial services | 2021 |
| CJR Renovations Ltd | Construction | 2019 |
| CKB Digital Ltd | Professional & scientific | 2025 |
| Ckbb Limited | Information & communication | 2024 |
| Ckor Limited | Extraterritorial | 2013 |
| CL Property and Renovations Ltd | Real estate | 2025 |
| Cladding Solutions South East Limited | Construction | 2021 |
| Claim-Blitz UK Ltd | Financial services | 2025 |
| Claimlink Property Management Limited | Households | 1987 |
| Clair Breen Limited | Administrative & support | 2007 |
| Claire Pitts & Co Ltd | Professional & scientific | 2008 |
| Claire's Doggy Daycare Ltd | Professional & scientific | 2019 |
| Claires Gardening Ltd | Administrative & support | 2026 |
| Clan (Romney Marsh) Limited | Financial services | 2017 |
| Claremetais Ltd | Health & social care | 2026 |
| Clarendon Capital Partners Ltd | Real estate | 2022 |
| Clarita Consultancy Limited | Education | 2016 |
| Clarity Logistics Ltd | Transport & logistics | 2025 |
| Clarity Media Services Limited | Information & communication | 2015 |
| Clark & Family Holdings Limited | Financial services | 2026 |
| Clarus Homes (Alkham) Limited | Construction | 2024 |
| Clarus Homes (Bethersden) Limited | Construction | 2018 |
| Clarus Homes (Chartham) Limited | Construction | 2020 |
| Clarus Homes (Design & Build) Ltd | Construction | 2012 |
| Clarus Homes (Godinton Road) Limited | Construction | 2019 |
| Clarus Homes (Goudhurst) Limited | Construction | 2022 |
| Clarus Homes (Great Chart) Limited | Construction | 2020 |
| Clarus Homes (HOP Pocket) Limited | Construction | 2020 |
| Clarus Homes (Lamberhurst) Limited | Construction | 2021 |
| Clarus Homes (Lamberhurst) Partnership LLP | | 2021 |
| Clarus Homes (Little Hookstead) Limited | Construction | 2020 |
| Clarus Homes (Saltwood) Limited | Construction | 2023 |
| Clarus Residents Little Hookstead Farm Limited | Households | 2021 |
| Clarus Solutions Limited | Construction | 2006 |
| Class Cars Limited | Wholesale & retail | 2023 |
| Classic Barber Ashford Ltd | Other services | 2019 |
| Classic Dental Laboratory Limited | Manufacturing | 2025 |
| Classic Design Builders Limited | Construction | 2014 |
| Classic Lettings Limited | Real estate | 2013 |
| Clavis Care Limited | Health & social care | 2024 |
| Clavis Construction Limited | Construction | 2023 |
| Clavis Group Limited | Real estate | 2018 |
| Clay Construction London Limited | Construction | 2022 |
| Claydon Medical Limited | Health & social care | 2023 |
| Claymore Tactical Solutions Ltd | Information & communication | 2026 |
| CLD Hire Limited | Administrative & support | 2026 |
| Clean to Perfection Kent Ltd | Administrative & support | 2023 |
| Cleanestry Services Limited | Administrative & support | 2017 |
| Cleaning Ventilation Services Limited | Administrative & support | 2005 |
| CLEANTECH360 Limited | Administrative & support | 2011 |
| Clear Cleaning Limited | Administrative & support | 2017 |
| Clear CUT Construction Building Serv Ltd | Construction | 2023 |
| Clear Facilities Management Limited | Administrative & support | 2003 |
| Clear LAB Limited | Manufacturing | 2022 |
| Clear Pass Traffic Control Ltd | Construction | 2024 |
| Clearcut Venues Limited | Administrative & support | 2017 |
| Cleared Europe Services Limited | Information & communication | 2014 |
| Clearlite Limited | Information & communication | 2022 |
| Clearlymph Ltd | Health & social care | 2020 |
| Clearport Ltd | Professional & scientific | 2026 |
| Clearsign Interpreting Limited | Professional & scientific | 2023 |
| Clearsky Healthcare Ltd | Wholesale & retail | 2024 |
| Clearwater Carwash Ltd | Administrative & support | 2025 |
| Clearway Site Services Limited | Construction | 2019 |
| Clearway Vehicle Services Ltd | Administrative & support | 2025 |
| Clearworks Services Ltd | Construction | 2025 |
| Clements Building Services Ltd | Construction | 2021 |
| Clements Driving School Ltd | Education | 2022 |
| Cleo Systems 24 Ltd | Information & communication | 2011 |
| Clerkenwell Media and Events Ltd | Professional & scientific | 2020 |
| Clevedon Court Management Company Limited | Water & waste | 1995 |
| Click Service Team Ltd | Construction | 2024 |
| CLICK22 Ltd | Wholesale & retail | 2022 |
| Clickon Wardrobes Limited | Administrative & support | 2005 |
| Clifford Solutions & Partnerships Limited | Extraterritorial | 2024 |
| Clima-Tec Heating & Cooling Ltd | Construction | 2025 |
| Climate Subak CIC | Administrative & support | 2020 |
| Climetrek Ltd | Financial services | 2021 |
| Clinic 124 Limited | Health & social care | 2021 |
| Clinical Communications Limited | Health & social care | 2003 |
| Clinical Practice Limited | Information & communication | 1999 |
| Clip Drape International Limited | Manufacturing | 2006 |
| Clive Emson Limited | Extraterritorial | 2006 |
| Clive Laurence Homes Ltd | Construction | 2019 |
| Clive Media Limited | Administrative & support | 2003 |
| CLK Brothers Group Ltd | Wholesale & retail | 2020 |
| CLN Logistics Ltd | Transport & logistics | 2019 |
| Close to Home Bespoke Limited | Construction | 2020 |
| Closer Independent Financial Services Limited | Professional & scientific | 2021 |
| Cloud Consent Technologies Ltd | Information & communication | 2025 |
| Cloud World Ltd | Information & communication | 2024 |
| Cloudfoxit Ltd | Information & communication | 2016 |
| Clouds Cards & Gifts Limited | Wholesale & retail | 1998 |
| Clough Engineering Partners (CEP) Ltd | Construction | 2024 |
| CLS Relations Limited | Professional & scientific | 2023 |
| Clubhouse Wines Ltd | Financial services | 2026 |
| Cluck U Ltd | Hospitality | 2021 |
| Clyfton Properties Ltd | Real estate | 2020 |
| CM Squelch Limited | Professional & scientific | 2011 |