| Claire Broad Design Limited | Manufacturing | 2025 |
| Claire Long Consultancy Ltd | Professional & scientific | 2022 |
| Clamiranha Ltd | Transport & logistics | 2019 |
| Clapham Park Property Limited | Real estate | 2021 |
| Clarendon Fine Art Holdings Limited | Professional & scientific | 2021 |
| Clarendon Fine Art Limited | Extraterritorial | 2012 |
| Clarify PR Limited | Professional & scientific | 2020 |
| Clarion Information Systems Limited | Information & communication | 2015 |
| Clarissa L Brown Limited | Information & communication | 2026 |
| Clark C Holdings Ltd | Financial services | 2023 |
| Clarke Contractors Limited | Construction | 2013 |
| Clarke Gemini International Limited | Wholesale & retail | 2003 |
| Clarson Investments Limited | Real estate | 2024 |
| Clarson Limited | Extraterritorial | 2025 |
| Class 107 Limited | Transport & logistics | 1997 |
| Class Credit Limited | Professional & scientific | 2009 |
| Classica Collection Limited | Wholesale & retail | 1998 |
| Classique Luxe Ltd | Wholesale & retail | 2023 |
| Claye Lettings and Estates Limited | Real estate | 2021 |
| CLD Projects Ltd | Hospitality | 2026 |
| Clean Carbs Ltd | Hospitality | 2025 |
| Cleanlandfill Co. Limited | Mining & quarrying | 1998 |
| Clear & Creative Limited | Professional & scientific | 2011 |
| Clear Accounting Lichfield Limited | Professional & scientific | 2022 |
| Clear ALL Limited | Water & waste | 2026 |
| Clear Audiology Ltd | Health & social care | 2022 |
| Clear Future Projects Limited | Health & social care | 2025 |
| Clear Path Care Limited | Health & social care | 2021 |
| Clear Vision Development Limited | Professional & scientific | 2008 |
| Clearfield Anderson Ltd | Wholesale & retail | 2025 |
| Cleartabs Limited | Information & communication | 2009 |
| Clearvision Consulting (UK) Limited | Professional & scientific | 2002 |
| Cleeve Business Machines Limited | Manufacturing | 2002 |
| Clembini Associates Limited | Real estate | 2017 |
| Cleminson Properties Limited | Real estate | 2026 |
| Clemson Grab Hire Ltd | Water & waste | 2026 |
| Cleveland Mews Management Company Limited | Real estate | 2002 |
| Clever Digital Industry Limited | Professional & scientific | 2023 |
| CLF Gifts Ltd | Wholesale & retail | 2024 |
| CLH Accounts and Tax Ltd | Professional & scientific | 2015 |
| Click Crafters Ltd | Professional & scientific | 2023 |
| Click Post Ltd | Manufacturing | 2016 |
| Client Edge Ltd | Information & communication | 2025 |
| Climate Care Services UK Limited | Energy | 2015 |
| Clink Weddings & Events Ltd | Administrative & support | 2026 |
| Clive Harrison (Agricultural) Ltd | Administrative & support | 2006 |
| Clive Thompson Installations Limited | Manufacturing | 2008 |
| CLJ Renders Holdings Limited | Financial services | 2014 |
| Cloud Business Technologies Limited | Information & communication | 2017 |
| Cloud Labels Ltd | Wholesale & retail | 2019 |
| Cloudinteract Holdings Limited | Financial services | 2024 |
| Cloudinteract Limited | Information & communication | 2022 |
| Clsm Properties Limited | Real estate | 2011 |
| Cluck IT UP Limited | Hospitality | 2025 |
| CMA Financial Introductions Limited | Administrative & support | 2007 |
| CME Utilities Ltd | Energy | 2023 |
| CMI2023 Limited | Financial services | 2023 |
| CNC Machining Ltd | Manufacturing | 2025 |
| Co-Op Energy Limited | Information & communication | 2010 |
| Co-Op Travel Direct Limited | Professional & scientific | 1997 |
| Co-Op Travel Limited | Administrative & support | 1993 |
| Co-Operative Energy Limited | Information & communication | 2009 |
| Co-Operative Payroll Giving Limited | Professional & scientific | 2011 |
| Coach GAP Lane Management Company Limited | Real estate | 2014 |
| Coalville Surfacing Limited | Construction | 1998 |
| Cobbleprint Limited | Construction | 2016 |
| Cobley Wellbeing Limited | Arts & recreation | 2018 |
| Cocker Hoop Creative Ltd | Hospitality | 2016 |
| Cockerill Maintenance Limited | Administrative & support | 2021 |
| Cocoonfms Limited | Information & communication | 2020 |
| Cocoonfxmedia Limited | Information & communication | 2010 |
| Code 6 Developments Limited | Professional & scientific | 2007 |
| Coffee Shops Limited | Extraterritorial | 2009 |
| COG Live Ltd | Administrative & support | 2022 |
| Cohesion Limited | Administrative & support | 2004 |
| Coins and Collectibles Limited | Wholesale & retail | 2025 |
| Cole Marketing Management Limited | Professional & scientific | 2024 |
| Collaborative Synergy Ltd. | Professional & scientific | 2021 |
| Collective Financial Planning Limited | Financial services | 2012 |
| Collins and Wells Limited | Professional & scientific | 2020 |
| Collsys Limited | Administrative & support | 2000 |
| Colmore Creative Limited | Professional & scientific | 2016 |
| Colour Brick Cosmetics Limited | Construction | 2016 |
| Colourstead Ltd | Wholesale & retail | 2026 |
| Colton Hall Farming Limited | Extraterritorial | 2012 |
| Comdex Digital Limited | Professional & scientific | 2017 |
| Comet Carpet Co Limited | Wholesale & retail | 1998 |
| Commercial Finance Network Corporation Ltd | Financial services | 2017 |
| Commercial Finance Network Limited | Financial services | 2016 |
| Commercial Health and Safety Solutions Ltd | Administrative & support | 2012 |
| Common Curiosity Limited | Professional & scientific | 2014 |
| Common Sense Food Consultancy Limited | Professional & scientific | 2018 |
| Compliance Holdings Ltd | Administrative & support | 2020 |
| Componenta UK Limited | Wholesale & retail | 1979 |
| Compound Rotary Engines Limited | Professional & scientific | 2009 |
| Concept Padel Limited | Wholesale & retail | 2026 |
| Conkane Properties Ltd | Construction | 2019 |
| Connect Edpsych Limited | Education | 2025 |
| Connect Recruitment Partners Limited | Other services | 2025 |
| Connect to Guardian Ltd | Other services | 2014 |