| CLS Partners Limited | Financial services | 2023 |
| Clsb Ltd | Manufacturing | 2023 |
| Clydesdale TA Ltd | Information & communication | 2026 |
| CM Cornice Ltd | Construction | 2022 |
| CM Paddocks Holdings Limited | Financial services | 2019 |
| CMF Finance Ltd | Professional & scientific | 2019 |
| CML Advisers Limited | Professional & scientific | 2023 |
| Cmoventures Ltd | Wholesale & retail | 2022 |
| CMS DRY Cleaners & Laundrette Ltd | Professional & scientific | 2009 |
| CN Taverns Limited | Hospitality | 2015 |
| CNE Investments Ltd | Real estate | 2019 |
| CNS Consult Ltd | Professional & scientific | 2017 |
| Co Drives Ltd | Transport & logistics | 2024 |
| Coach Chris C Ltd | Arts & recreation | 2024 |
| Coal and Curry Ltd | Hospitality | 2023 |
| Coastway Properties Limited | Real estate | 1998 |
| Cobalt Search Ltd | Administrative & support | 2018 |
| Cobra Shipping UK Limited | Transport & logistics | 2015 |
| Cobweb Limited | Information & communication | 1998 |
| COC (UK) Ltd | Administrative & support | 2012 |
| Cockfosters Nails #1 Ltd | Other services | 2025 |
| Cocktail Cabinet Co London Ltd | Wholesale & retail | 2022 |
| Cocreatd Limited | Professional & scientific | 2024 |
| Codax Limited | Other services | 2012 |
| Codehands Limited | Information & communication | 2018 |
| Coevolve Chadwick Limited | Real estate | 2016 |
| Coevolve Limited | Construction | 2016 |
| Coffee &Matcha Ltd | Hospitality | 2024 |
| Coffee Bean Cafe Limited | Hospitality | 2025 |
| Coffee Bean Express Limited | Hospitality | 2019 |
| Cogan Limited | Administrative & support | 2016 |
| Cognis Capital Partners Limited | Financial services | 2019 |
| Cognita Consultancy Limited | Professional & scientific | 2018 |
| Cognitive Realm Ltd | Information & communication | 2026 |
| Cognitiveia Limited | Information & communication | 2016 |
| Cognitte Limited | Other services | 2019 |
| Cohabit Limited | Real estate | 2014 |
| Colab Offices Ltd | Real estate | 2020 |
| Colchester Capital Ltd | Professional & scientific | 2024 |
| Coldpressconsulting Limited | Real estate | 2012 |
| Coldstream Media Limited | Information & communication | 2026 |
| Collectagift Limited | Other services | 2020 |
| Collingwood Capital Limited | Administrative & support | 2016 |
| Colony Interiors Limited | Wholesale & retail | 2015 |
| Coloringpage Ltd | Professional & scientific | 2025 |
| Colour Boutique Nail Bar Ltd | Other services | 2022 |
| Com-Assist Ltd | Information & communication | 2023 |
| Comanche Warbirds Limited | Administrative & support | 2012 |
| Combesgate Holdings Limited | Administrative & support | 2023 |
| Combined Timber Frame Manufacturers Limited | Construction | 2015 |
| Comfy Consortium Limited | Information & communication | 2008 |
| Commerce Energy Limited | Construction | 2011 |
| Commercial Cleaning and Support Services Limited | Administrative & support | 2018 |
| Commercial Minds Ltd | Extraterritorial | 2006 |
| Commerz Ltd | Wholesale & retail | 2025 |
| Comms Direct (UK) Ltd | Information & communication | 2008 |
| Communications and Trading Limited | Wholesale & retail | 1995 |
| Community Support CIC | Hospitality | 2022 |
| Company of London Limited | Professional & scientific | 2014 |
| Compass Land Management Ltd | Real estate | 2018 |
| Compassion Healthcare 24/7 Limited | Health & social care | 2024 |
| Compassion Healthcare Staffing Services Ltd | Administrative & support | 2017 |
| Compassionate Care Home Ltd | Health & social care | 2014 |
| Competas Global Limited | Administrative & support | 2015 |
| Complete Food Safety Limited | Professional & scientific | 2008 |
| Complete on Site Support LLP | | 2011 |
| Complete Rental & Maintenance Ltd | Real estate | 2022 |
| Compliance Academy Limited | Administrative & support | 2022 |
| Compliance Specialists Limited | Financial services | 2021 |
| Computer Tutoring Limited | Information & communication | 2002 |
| Conance Limited | Financial services | 1985 |
| Concept Cameras Limited | Other services | 2009 |
| Concept Origin Ltd | Other services | 2023 |
| Concerto Software & Systems (UK) Limited | Information & communication | 2026 |
| Concise Insights Ltd | Professional & scientific | 2023 |
| Condici Limited | Wholesale & retail | 1982 |
| Conexus International Recruitment Limited | Professional & scientific | 2019 |
| Coneygree LLP | | 2020 |
| Confexpo Global Ltd | Administrative & support | 2020 |
| Confident Friendly Driving Limited | Education | 2014 |
| Connaught Avenue Limited | Households | 2012 |
| Connaught Gardens Ltd | Households | 2024 |
| Connect Accounting LLP | | 2015 |
| Connect Business Limited | Professional & scientific | 2022 |
| Connect Global Service Limited | Information & communication | 2025 |
| Connect Survey Services Limited | Administrative & support | 2011 |
| Connecting Insight Limited | Administrative & support | 2010 |
| Connections Telecoms Limited | Information & communication | 2001 |
| Connective Electrical Solutions Limited | Other services | 2018 |
| Connell Roberts Developments Ltd | Construction | 2025 |
| Connor Estates Ltd | Construction | 2017 |
| Connor Park Estates Ltd | Construction | 2017 |
| Connor Park Homes Limited | Construction | 2015 |
| Connor Realty Limited | Real estate | 2016 |
| Connx Ltd | Information & communication | 2016 |
| Consolegoods Ltd | Other services | 2019 |
| Consolenet Limited | Wholesale & retail | 2009 |
| Consolidated Artistes Limited | Arts & recreation | 2024 |
| Consolidated Service Industries Ltd | Professional & scientific | 1994 |
| Constable Three Ltd | Administrative & support | 2022 |