| Clarendon Park Road Management Company 2003 Limited | Households | 2003 |
| Clarendon Perk Ltd | Hospitality | 2025 |
| Clarendon Pharma Limited | Wholesale & retail | 2025 |
| Clarendon Property Group Limited | Real estate | 2021 |
| Clarendon Property Holdings Ltd | Real estate | 2023 |
| Clarendon Spice Limited | Hospitality | 2023 |
| Clarendon Springs Ltd | Wholesale & retail | 2024 |
| Clarendon Wellbeing Ltd | Administrative & support | 2022 |
| Clarenza Ltd | Information & communication | 2024 |
| Clareyard Limited | Administrative & support | 2025 |
| Claridge Holdco Limited | Financial services | 2023 |
| Claridge Inc Limited | Extraterritorial | 2014 |
| Claridge Nursing Homes (Hampton Grange) Limited | Health & social care | 2004 |
| Claridge Nursing Homes (Lynhales Hall) Limited | Health & social care | 2003 |
| Claridge Nursing Homes Limited | Health & social care | 2010 |
| Clarion Field Mobile Home Park Limited | Hospitality | 2018 |
| Clarity Academy Ltd | Professional & scientific | 2004 |
| Clarity Results Ltd | Information & communication | 2018 |
| Clarity Studios Ltd | Information & communication | 2025 |
| Claritydrive.Uk Ltd | Professional & scientific | 2025 |
| Clarium Limited | Professional & scientific | 2025 |
| Clark & Clark Limited | Real estate | 2015 |
| Clark & English Newark Limited | Professional & scientific | 2019 |
| Clark Elite Performance Ltd | Arts & recreation | 2025 |
| Clark Productions Limited | Information & communication | 2016 |
| Clarke's Assets Limited | Real estate | 2025 |
| Clarke-Coles Ltd | Wholesale & retail | 2012 |
| CLAROSA3 Ltd. | Real estate | 2016 |
| Class and Heritage Design Studio Ltd | Professional & scientific | 2026 |
| Class Online Ltd | Wholesale & retail | 2026 |
| Classic & Sports Car Transport Ltd | Transport & logistics | 2016 |
| Classic Car Services Limited | Wholesale & retail | 2005 |
| Classic Carpets & Furniture Ltd | Wholesale & retail | 2020 |
| Classic Cuts Groby Limited | Other services | 2003 |
| Classic Edge Ltd | Wholesale & retail | 2023 |
| Classic Events Ltd | Information & communication | 2025 |
| Classic Interiors 2001 Limited | Wholesale & retail | 2006 |
| Classic Kitchens & Interior Ltd | Manufacturing | 2016 |
| Classic Line Insurance Services Limited | Financial services | 1992 |
| Classic Photo Supplies Ltd | Professional & scientific | 2020 |
| Classic Renovation Ltd | Manufacturing | 2025 |
| Classic Sash Windows & Carpentry Limited | Administrative & support | 2002 |
| Classical Brass Limited | Professional & scientific | 1984 |
| Classical Windows & Repairs Limited | Construction | 2009 |
| Classiq Solutions Ltd | Construction | 2013 |
| Classy Food Limited | Hospitality | 2021 |
| Classy Nights Accommodation Ltd | Real estate | 2024 |
| Clave Solutions Ltd | Information & communication | 2026 |
| Clavenne Ltd | Wholesale & retail | 2026 |
| Claw Kingdom Ltd | Financial services | 2025 |
| Clawson MVK Limited | Information & communication | 2014 |
| Clay's Doors & Window Repairs Ltd | Other services | 2019 |
| Clays Butchers Ltd | Extraterritorial | 2012 |
| Claysar Ltd | Professional & scientific | 2018 |
| Claytonkemp Holdings Limited | Financial services | 2022 |
| Claytonkemp Pension Company Limited | Professional & scientific | 2024 |
| Clayworth Greatest Ltd | Administrative & support | 2014 |
| CLB Cleanequip Ltd | Manufacturing | 2012 |
| CLB Duct Works Limited | Manufacturing | 2023 |
| CLC Property Investments Limited | Real estate | 2023 |
| CLC Transport Ltd | Transport & logistics | 2024 |
| Clcy Propco Limited | Hospitality | 2025 |
| Clean & Natural Ltd | Other services | 2014 |
| Clean Electricity Generation Holding UK Limited | Financial services | 2016 |
| Clean My Crib Ltd | Administrative & support | 2022 |
| Clean Vibes 1 Ltd | Administrative & support | 2026 |
| Clean Wealth Ltd | Wholesale & retail | 2024 |
| Clean With Green Ltd | Manufacturing | 2023 |
| Clean World Technology Africa Ltd | Financial services | 2025 |
| Clean World Technology Engineering Ltd | Financial services | 2024 |
| Clean World Technology Limited | Professional & scientific | 2020 |
| Clean World Technology TM Ltd | Financial services | 2022 |
| CLEAN2GO Cleaning Services Limited | Administrative & support | 2016 |
| Cleanaf Ltd | Administrative & support | 2009 |
| Cleanall Cleaners Ltd | Administrative & support | 2026 |
| Cleanbritian Ltd | Administrative & support | 2026 |
| Cleanglow Ltd | Transport & logistics | 2025 |
| Cleaning Cloth Limited | Administrative & support | 2026 |
| Cleaning DR Limited | Administrative & support | 2026 |
| Cleaning Roofs, Garden and Waste Collection Limited | Water & waste | 2022 |
| Cleaning Stations Limited | Extraterritorial | 2023 |
| Cleanliness Ltd | Manufacturing | 2001 |
| Cleanwell Leicester Ltd | Administrative & support | 2011 |
| Clear Automotive Recruitment Solutions Limited | Administrative & support | 2020 |
| Clear Brew Derby Limited | Administrative & support | 2019 |
| Clear Canopy Solutions Ltd | Information & communication | 2019 |
| Clear Collective Ltd | Real estate | 2011 |
| Clear Fashion Ltd | Manufacturing | 2024 |
| Clear Financial Thinking Limited | Professional & scientific | 2012 |
| Clear Flow Water Treatment Limited | Water & waste | 2016 |
| Clear Guidance Ltd | Education | 2025 |
| Clear Ledger Accounting Limited | Professional & scientific | 2026 |
| Clear Path Accountancy Ltd | Extraterritorial | 2020 |
| Clear Point Training Ltd | Education | 2019 |
| Clear Sky Financial Consulting Limited | Financial services | 2010 |
| Clear Sky Group Ltd | Financial services | 2017 |
| Clear Sky Healing (Bradford) CIC | Health & social care | 2025 |
| Clear Sky Legal Services Ltd | Other services | 2019 |
| Clear Sky Lettings Ltd | Real estate | 2017 |
| Clear Sky Management Limited | Administrative & support | 2025 |