| Clarice Essentials Ltd | Hospitality | 2024 |
| Clarissas Ltd | Other services | 2026 |
| Clarity Analytics Ltd | Information & communication | 2024 |
| Clarity Copiers (Wessex) Limited | Administrative & support | 2006 |
| Clarity License Management Limited | Professional & scientific | 2012 |
| Clarity Rewards Ltd | Professional & scientific | 2025 |
| Clark Carpentry Limited | Construction | 2011 |
| Clark Cobden Ltd | Households | 2018 |
| Clark Procurement Services Limited | Professional & scientific | 1997 |
| Clarkan Trading Ltd | Real estate | 2022 |
| Clarke Bridge Solutions Ltd | Administrative & support | 2019 |
| Clarke Home Renovations Limited | Construction | 2000 |
| Clarke Reddy Limited | Real estate | 2015 |
| Clarke Willmott Limited | Professional & scientific | 2002 |
| Clarke Willmott LLP | | 2009 |
| Clarke Willmott Trust Corporation Limited | Administrative & support | 2006 |
| Clarkes Dairy Limited | Wholesale & retail | 2003 |
| Clash Media Limited | Professional & scientific | 2019 |
| Classic Construction (Southern) Ltd | Construction | 2001 |
| Classic Finish (UK) Limited | Construction | 2003 |
| Classic Fire & Security Limited | Public administration | 2006 |
| Classic Home Improvements (Southampton) Limited | Manufacturing | 1996 |
| Classic Marquees Limited | Other services | 1996 |
| Classic Vehicle Valuation Services Ltd | Financial services | 2025 |
| Classic Yacht Maintenance Limited | Other services | 2020 |
| Classy Care Services Ltd | Public administration | 2026 |
| Classy Nails (UK) Ltd | Other services | 2012 |
| Classycedar UK Ltd | Wholesale & retail | 2024 |
| Claudiu and Anamaria Ltd | Health & social care | 2019 |
| Clausentum Curae Ltd | Health & social care | 2018 |
| Clausentum Homes Ltd | Construction | 2016 |
| Clausentum Investments Limited | Real estate | 2014 |
| Clausentum Masonic Hall Limited | Other services | 2024 |
| Clavaj Ltd | Wholesale & retail | 2024 |
| Clay & Slate Group Holdings Limited | Construction | 2021 |
| Clay & Slate Roofing Products Limited | Construction | 2010 |
| Clayford London Limited | Administrative & support | 2010 |
| Clayhill Farm Limited | Hospitality | 2007 |
| Claylingua Limited | Information & communication | 2025 |
| CLD Barbershop Ltd | Other services | 2026 |
| CLE Acreage Ltd | Transport & logistics | 2026 |
| Cleabarrow Investments Limited | Financial services | 2021 |
| Cleabarrow Limited | Financial services | 2009 |
| Clean & Build South Ltd | Administrative & support | 2019 |
| Clean Air Solutions UK Ltd | Construction | 2024 |
| Clean Air Stoves Ltd | Construction | 2019 |
| Clean Club Services Ltd | Administrative & support | 2021 |
| Clean Club Solutions Limited | Administrative & support | 2024 |
| Clean Freaks Group Limited | Administrative & support | 2023 |
| Clean Getaway Limited | Administrative & support | 2011 |
| Clean Peak Southampton Ltd | Administrative & support | 2024 |
| Clean Slate Carpet Cleaning Ltd | Administrative & support | 2025 |
| Clean Solutions Ltd | Administrative & support | 2025 |
| Clean Spark Services Ltd Ltd | Administrative & support | 2022 |
| Cleanall Exteriors Ltd | Administrative & support | 2017 |
| Cleanatomy Premier Cleaning Limited | Administrative & support | 2025 |
| Cleanbee Homes & Services Limited | Real estate | 2024 |
| Cleaned Right Ltd | Administrative & support | 2025 |
| CLEANHOUSE1975 Limited | Administrative & support | 2025 |
| Cleaning Culture Ltd | Administrative & support | 2025 |
| Cleaning Equipment Supplies Limited | Extraterritorial | 1997 |
| Cleaning Operations UK Limited | Administrative & support | 2013 |
| Cleaning Solutions Made Simple Ltd | Administrative & support | 2019 |
| CLEANING&MAINTANANCE2025 Limited | Administrative & support | 2025 |
| Cleanreports Ltd | Information & communication | 2026 |
| Clear Clean (South) UK Ltd | Administrative & support | 2018 |
| Clear Corporate Solutions Limited | Professional & scientific | 2013 |
| Clear Drainage Ltd | Administrative & support | 2026 |
| Clear Financial Planners Limited | Professional & scientific | 2016 |
| Clear OUT Group Ltd | Water & waste | 2022 |
| Clear UP Pet Waste Hygiene Specialist Ltd | Water & waste | 2026 |
| Cleare HR Consulting Limited | Professional & scientific | 2014 |
| Clearflow Guttering Limited | Administrative & support | 2021 |
| Clearline ARB Limited | Administrative & support | 2020 |
| Clearpro Services Ltd | Administrative & support | 2026 |
| Clearsafe Asbestos Ltd | Water & waste | 2017 |
| Clearsafe Environmental Ltd | Water & waste | 2023 |
| Clearseas Maritime Ltd | Professional & scientific | 2023 |
| Clearstone Creative Ltd | Professional & scientific | 2026 |
| Clearstone Property Limited | Real estate | 2025 |
| Clearview Business Solutions Limited | Professional & scientific | 2002 |
| Clearview Digital Media Ltd | Wholesale & retail | 2026 |
| Clearview Window Systems Limited | Construction | 1997 |
| Clearvision Properties (Southern) Limited | Real estate | 2018 |
| Clearwater Financial Projects Limited | Construction | 2000 |
| Clearwater Sensors Ltd | Manufacturing | 2019 |
| Clee&Dissa Busy Corner Ltd | Hospitality | 2026 |
| Cleeyae Limited | Wholesale & retail | 2021 |
| Clemard Consulting Limited | Professional & scientific | 2023 |
| Clemens Brothers Holdings Limited | Financial services | 2020 |
| Clement Properties Limited | Real estate | 2016 |
| Cleo Lagos Limited | Wholesale & retail | 2019 |
| Clever Bunny Ltd | Information & communication | 2016 |
| Clever Clogs Contractors Limited | Professional & scientific | 2012 |
| Clever PIG Productions Limited | Information & communication | 2012 |
| Cleverley Installations Ltd | Wholesale & retail | 2025 |
| Cleverly Group Limited | Financial services | 2018 |
| Cleverly Textiles Limited | Wholesale & retail | 2016 |
| Cleverness of U Ltd | Professional & scientific | 2016 |
| Clevora Ltd | Professional & scientific | 2025 |