| Clean Air Roads Limited | Water & waste | 2017 |
| Clean and Sparkle Cleaning Limited | Administrative & support | 2017 |
| Clean Beyond Limits Ltd | Administrative & support | 2025 |
| Clean CUT Design Ltd | Construction | 2025 |
| Clean Empire Solutions Ltd | Administrative & support | 2025 |
| Clean Fast Ltd | Professional & scientific | 2020 |
| Clean Glass Cardiff Ltd | Administrative & support | 2026 |
| Clean Home Stays Limited | Hospitality | 2017 |
| Clean IT Cardiff Rubbish Removals and Recycling Ltd | Water & waste | 2021 |
| Clean IT UP Ltd | Administrative & support | 2017 |
| Clean Safe Insulation Ltd | Construction | 2022 |
| Cleanbite Limited | Manufacturing | 2016 |
| Cleanhome Household UK Limited | Wholesale & retail | 2020 |
| Cleaning B'S Ltd | Administrative & support | 2019 |
| Cleaning Made Simple Limited | Other services | 2014 |
| Cleaning Restore Services Ltd | Administrative & support | 2019 |
| Cleanless England Ltd | Administrative & support | 2024 |
| Cleanmama Ltd | Other services | 2024 |
| Cleanminds Ltd | Administrative & support | 2024 |
| Cleanmyplace Technologies Ltd | Other services | 2023 |
| Cleanology Group Limited | Administrative & support | 2026 |
| Cleanplus Ltd | Wholesale & retail | 2019 |
| Cleansure Solutions Ltd | Extraterritorial | 2026 |
| Cleanz Ltd | Administrative & support | 2020 |
| Clear Careers Limited | Administrative & support | 2016 |
| Clear Choice Cleaning & Maintenance Limited | Arts & recreation | 2008 |
| Clear Choice Developments Ltd | Construction | 2015 |
| Clear Digital Marketing & Creative Agency Ltd | Information & communication | 2020 |
| Clear Guide Data Ltd | Wholesale & retail | 2025 |
| Clear Horizons Coaching Ltd | Other services | 2025 |
| Clear Path Insights Consulting Limited | Professional & scientific | 2023 |
| Clear Red Campaigns Ltd | Professional & scientific | 2023 |
| Clear Stone Detox Limited | Health & social care | 2025 |
| Clear the FOG Ltd | Information & communication | 2021 |
| Clear Title Service Ltd | Professional & scientific | 2024 |
| Clear Translations Ltd | Administrative & support | 2012 |
| Clear View Housing Limited | Real estate | 2011 |
| Clear Vision Analytics Ltd | Information & communication | 2023 |
| Clear Vision Windows and Doors Ltd | Manufacturing | 2018 |
| CLEAR4WALES Ltd | Water & waste | 2025 |
| Clearance Stock Limited | Wholesale & retail | 2018 |
| Clearbright Solutions Ltd | Administrative & support | 2019 |
| Clearcare Worldwide Ltd | Financial services | 2025 |
| Clearchoice Staffing Ltd | Administrative & support | 2025 |
| Cleardydd Ltd | Administrative & support | 2025 |
| Clearpixel VR Ltd | Information & communication | 2020 |
| Clearquote Technologies Ltd | Information & communication | 2022 |
| Clearsight Accounting Limited | Professional & scientific | 2024 |
| Clearsight Holdings Limited | Financial services | 2025 |
| Clearspa Limited | Hospitality | 2004 |
| Clearspace Facilities Management Limited | Administrative & support | 2019 |
| Clearstone Enterprises Limited | Information & communication | 2025 |
| Cleartech Live Limited | Professional & scientific | 2013 |
| Cleartech Polymers Limited | Wholesale & retail | 1999 |
| Clearview Capital Bidco Limited | Arts & recreation | 2024 |
| Clearview Data Path Ltd | Information & communication | 2025 |
| Clearview Payroll Solutions Ltd | Administrative & support | 2025 |
| Clearview Radiology Ltd | Health & social care | 2023 |
| Clearvisions Consulting Limited | Professional & scientific | 2025 |
| Clearvoice Transcription Ltd | Administrative & support | 2024 |
| Clearwater Payroll Services Ltd | Administrative & support | 2015 |
| Clearway Court Residents Company Limited | Households | 2009 |
| Clearwell Recruitment Ltd | Administrative & support | 2019 |
| Cleator Pizza Limited | Hospitality | 2025 |
| Clee Meadows Ltd | Construction | 2017 |
| Cleen Green Energy Limited | Professional & scientific | 2012 |
| Clefax Ltd | Health & social care | 2018 |
| Clemeans Ltd | Wholesale & retail | 2022 |
| Clement Creatives LLP | | 2025 |
| Clement Hill Limited | Professional & scientific | 2014 |
| Clement Inc PC | | 2018 |
| Clements & Co Solicitors Limited | Professional & scientific | 2021 |
| Clementy Ltd | Wholesale & retail | 2020 |
| Clenew Ltd | Wholesale & retail | 2020 |
| Cleolilith Ltd | Wholesale & retail | 2025 |
| Cleopatra Cardiff Ltd | Hospitality | 2020 |
| Cleopatra Ltd | Professional & scientific | 2019 |
| Cles Fonctionnel Limited | Mining & quarrying | 2021 |
| Clevar Technology Ltd | Information & communication | 2019 |
| Cleve Construction Design & Build Ltd | Construction | 2019 |
| Cleveland Shotblasting Limited | Wholesale & retail | 1976 |
| Clever Construction Solutions Ltd. | Construction | 2012 |
| Clever Rise Ltd | Professional & scientific | 2019 |
| Clever Spaces Ltd | Manufacturing | 2009 |
| Cleverchefs Catering Limited | Hospitality | 2025 |
| Cleverchefs Commercial Catering Limited | Hospitality | 2026 |
| Cleverchefs Group Holdings Ltd | Hospitality | 2016 |
| Cleverly Done Studios Ltd | Information & communication | 2026 |
| Clevni Ltd | Wholesale & retail | 2025 |
| Clevo Technology Co., Ltd. | Administrative & support | 2020 |
| Clevora Global Ltd | Wholesale & retail | 2025 |
| Clevoro Ltd | Wholesale & retail | 2025 |
| Clevver Estate & Letting Agents Limited | Real estate | 2021 |
| Click a Brick Ltd | Real estate | 2020 |
| Click and Collect Cars Limited | Administrative & support | 2017 |
| Click on Herts Limited | Other services | 2013 |
| Click Search Media Limited | Financial services | 2011 |
| Click Vision Marketing Ltd | Professional & scientific | 2019 |
| Click-Away Shop Ltd | Wholesale & retail | 2024 |
| Clickcart INT Ltd | Wholesale & retail | 2025 |