| Classic Utensils UK Ltd | Wholesale & retail | 2025 |
| Classy Doll Aesthetics Academy Ltd | Other services | 2022 |
| Claudia Morris Design Ltd | Professional & scientific | 2025 |
| Clay Frame Consultancy Limited | Professional & scientific | 2022 |
| Clayclean Ltd | Other services | 2018 |
| Clean & Fresh Cleaning Services Ltd | Administrative & support | 2018 |
| Clean Motion Hire Ltd | Administrative & support | 2026 |
| Cleanie Ltd | Administrative & support | 2019 |
| Cleanie Specialist Cleaning Services Ltd | Administrative & support | 2024 |
| Cleaning Service PIK Ltd | Administrative & support | 2024 |
| Clear Cleaning and Domestic Work Limited | Administrative & support | 2026 |
| Clear Environmental Contracting London Limited | Administrative & support | 2001 |
| Clear Path Analysis Limited | Professional & scientific | 2010 |
| Clear PAY Contracts Limited | Other services | 2018 |
| Clear Thinking IT Limited | Information & communication | 2006 |
| Clear Waste Removal Ltd | Water & waste | 2025 |
| CLEAR2GO Ltd | Other services | 2021 |
| Clearline Solutions Ltd | Construction | 2025 |
| Clearmind Living Limited | Health & social care | 2026 |
| Clearpane Windows Ltd | Construction | 2026 |
| Clearsignal Ltd | Professional & scientific | 2026 |
| Cleartone EAR WAX Removal Clinic Ltd | Health & social care | 2024 |
| Clearview Home Solutions Ltd. | Construction | 2019 |
| Clegg Estates Limited | Real estate | 2021 |
| Clemence (CG) Limited | Professional & scientific | 1983 |
| Clemence (CM) Limited | Real estate | 1961 |
| Clemence (KS) Limited | Professional & scientific | 1988 |
| Clemence (LR) Limited | Real estate | 1983 |
| Clemence (UK) Limited | Professional & scientific | 1990 |
| Clermont House Management Company Limited | Professional & scientific | 2021 |
| Clever Guys Ltd | Wholesale & retail | 2018 |
| Click N Go Limited | Wholesale & retail | 2025 |
| Click Print Deliver Ltd | Administrative & support | 2016 |
| Click Web Consulting Limited | Information & communication | 2011 |
| CLICK4ASSISTANCE Ltd | Information & communication | 2004 |
| Clickyclicks Ltd | Professional & scientific | 2018 |
| Clikz Ltd | Information & communication | 2025 |
| Climate Peace Alliance Ltd. | Extraterritorial | 2023 |
| Clinical Details Ltd | Manufacturing | 2023 |
| Clinicode Limited | Administrative & support | 2006 |
| Clintons Garage Limited | Wholesale & retail | 2024 |
| Clipcoach Ltd | Other services | 2025 |
| Clipper U.K. Ltd | Wholesale & retail | 2003 |
| Clock Tower Property Development Limited | Construction | 2014 |
| Close Brothers Cars Ltd | Wholesale & retail | 2025 |
| Cloud 9 Gold $$ Limited | Administrative & support | 2024 |
| Cloudcast Limited | Mining & quarrying | 1984 |
| Cloudsocio Ltd | Wholesale & retail | 2019 |
| Clout Cleaners Ltd | Administrative & support | 2024 |
| Clover Spray Limited | Wholesale & retail | 1988 |
| Clover Spring Limited | Health & social care | 2024 |
| CLR Specialised Services Limited | Professional & scientific | 2018 |
| CLS Coastline Scaffolding Limited | Other services | 2024 |
| CLS Services (U.K) Limited | Other services | 2014 |
| Club Enclosures Limited | Other services | 2025 |
| Club House Residents Association Limited | Households | 2008 |
| Club Kingswood Limited | Arts & recreation | 2005 |
| CLV Services Limited | Professional & scientific | 2018 |
| CM Basildon Limited | Other services | 2010 |
| CM Installations (Essex) Limited | Construction | 2016 |
| CM Maintenance Contracts Ltd | Construction | 2023 |
| CM Plumbing Ltd | Construction | 2023 |
| CM POP Ltd | Wholesale & retail | 2023 |
| Cmas Care Services Ltd | Health & social care | 2019 |
| CMC Construction M + E Limited | Construction | 2024 |
| CMC Technology Limited | Information & communication | 2024 |
| CMP Professional Services Ltd | Construction | 2018 |
| CMR Trading Limited | Other services | 2022 |
| CMV Trade Limited | Wholesale & retail | 2022 |
| CNB Properties Ltd | Real estate | 2020 |
| CND Connect Limited | Transport & logistics | 2023 |
| CND Construction Ltd | Construction | 2017 |
| CNH Industrial Capital Europe Limited | Financial services | 1997 |
| CNH Industrial N.V. | | 2012 |
| CNH Industrial N.V. | | 2022 |
| CNH Industrial Trading Limited | Wholesale & retail | 2026 |
| CNH Industrial UK Limited | Financial services | 2017 |
| CNI Construction Ltd | Construction | 2024 |
| CNS Management Ltd | Real estate | 2023 |
| Co&Mi Ltd | Construction | 2019 |
| Coach & BUS Travel Limited | Administrative & support | 2012 |
| Coached by Cian Limited | Other services | 2023 |
| Coaching on Demand Limited | Information & communication | 2019 |
| Coastline Scaffolding Hire Ltd | Administrative & support | 2019 |
| Cobra Custom Tattoos Limited | Other services | 2014 |
| Cobra Films Limited | Professional & scientific | 2013 |
| Cobra Productions Limited | Professional & scientific | 2018 |
| Cockbill Construction Limited | Construction | 2003 |
| Coco Cafe Plus Limited | Hospitality | 2023 |
| Cocup Astapor Limited | Wholesale & retail | 2025 |
| COD Father 007 Limited | Hospitality | 2018 |
| Codaj Limited | Health & social care | 2020 |
| Codecart Limited | Wholesale & retail | 2025 |
| Coder View Ltd | Information & communication | 2022 |
| Codespace Services Ltd | Information & communication | 2007 |
| Codewave Resourcing Ltd | Administrative & support | 2023 |
| Codeword Solutions Ltd | Information & communication | 2023 |
| COE Group Ltd. | Financial services | 2023 |
| Coffee Co Essex Limited | Wholesale & retail | 2025 |
| Cogent Construction Limited | Construction | 2022 |