| Clear Future Wealth Management Limited | Financial services | 2014 |
| Clear Line Assets Limited | Administrative & support | 2016 |
| Clear Line Holdings Ltd | Financial services | 2012 |
| Clear Line Limited | Construction | 1997 |
| Clear Line Maintenance Ltd | Construction | 1999 |
| Clear Logic Group Consulting Limited | Professional & scientific | 2024 |
| Clear Pill Ltd | Health & social care | 2014 |
| Clear Plumbing Solutions Limited | Construction | 2018 |
| Clear View Cleaning Ltd | Administrative & support | 2026 |
| Clearance and Clean UP Limited | Water & waste | 2011 |
| Clearcover Limited | Financial services | 2013 |
| Clearer Prospects Consultancy Limited | Health & social care | 2016 |
| Clearflow Products Ltd | Construction | 2007 |
| Clearfuture Limited | Real estate | 1986 |
| Clearlase Leeds Limited | Other services | 2024 |
| Clearlase Limited | Other services | 2022 |
| Clearlight Data Science Ltd | Information & communication | 2020 |
| Clearline Communications Limited | Information & communication | 1989 |
| Clearly Different Dentistry Limited | Health & social care | 2011 |
| Clearstep Podiatry & Chiropody Ltd | Health & social care | 2025 |
| Clearview Cloud Accounting Ltd | Professional & scientific | 2022 |
| Clearview Cloud Financial Limited | Professional & scientific | 2025 |
| Clearview Force Ltd | Administrative & support | 2025 |
| Clearview MED UK Limited | Manufacturing | 2010 |
| Clearview Property Solutions Ltd | Real estate | 2024 |
| Clearwater Industries Limited | Construction | 2005 |
| Clearwater Plumbing & Heating (South Yorkshire) Limited | Construction | 2006 |
| Clearwater Residentials Limited | Real estate | 2024 |
| Cleary Property Development Limited | Wholesale & retail | 2001 |
| Clee Hospitality Ltd | Hospitality | 2026 |
| Clegg Consultancy Ltd | Professional & scientific | 2019 |
| Clerewell Limited | Real estate | 1984 |
| Clever Clogs Children’S Shoes Ltd | Wholesale & retail | 2025 |
| Clflower Ltd | Wholesale & retail | 2025 |
| Clgc Ltd | Professional & scientific | 2016 |
| CLH Aesthetics Ltd | Other services | 2020 |
| CLH Landscaping Ltd | Administrative & support | 2020 |
| Click Hive Ltd | Professional & scientific | 2021 |
| Click IT Training Limited | Information & communication | 2008 |
| Click N Dispatch Ltd | Wholesale & retail | 2025 |
| Click Surge Ltd | Information & communication | 2025 |
| Clicklearner Ltd | Information & communication | 2012 |
| Clicknpick 365 Limited | Wholesale & retail | 2023 |
| Clickpromogifts Limited | Professional & scientific | 2007 |
| Clicksy Ltd | Information & communication | 2021 |
| Client Sphere Ltd | Other services | 2022 |
| Cliffe Motors Ltd | Wholesale & retail | 2024 |
| Clifton Builders Limited | Construction | 2011 |
| Clifton Car Exchange Limited | Wholesale & retail | 1996 |
| Clifton Cognate Properties Ltd | Construction | 2020 |
| Clifton Hill Property & Investments Limited | Real estate | 2022 |
| Clifton LV Ltd | Financial services | 2025 |
| Clifton Park Developments Limited | Construction | 2013 |
| Clifton Park View Residents Company Limited | Real estate | 2015 |
| Clima Heating Services Limited | Construction | 2015 |
| Climaclean Ltd T/A Green Machine Ltd | Administrative & support | 2021 |
| Climafleet UK Ltd | Energy | 2018 |
| Climate 2025 Limited | Professional & scientific | 2019 |
| Climate Warriors 4U Ltd | Construction | 2022 |
| Climb Hire Limited | Arts & recreation | 2013 |
| Climb Recruitment Limited | Administrative & support | 2019 |
| Climb the River Ltd | Professional & scientific | 2024 |
| Climbing Consultancy Limited | Professional & scientific | 2013 |
| Clindr Ltd | Professional & scientific | 2017 |
| Clinetics Medispa Limited | Administrative & support | 2018 |
| Clinical & Personal Care Ltd | Health & social care | 2019 |
| Clinics Operations Limited | Health & social care | 2021 |
| Clinker Estates Ltd | Real estate | 2021 |
| Clinker Wood Limited | Agriculture & fishing | 2025 |
| Clintec Holdings Ltd | Real estate | 2024 |
| Clintec Ltd. | Energy | 2015 |
| Clinton Anaesthesia Ltd | Health & social care | 2019 |
| Clinton Woods Enterprises Ltd | Arts & recreation | 2010 |
| Clip (South West) Limited | Health & social care | 2019 |
| CLIQ5 Technologies Ltd | Information & communication | 2026 |
| Clique Payment Tech Limited | Information & communication | 2022 |
| Clive Eyre Limited | Real estate | 1960 |
| CLL Engineering Ltd | Professional & scientific | 2014 |
| CLM Digital Marketing Ltd | Professional & scientific | 2023 |
| Clmachin Ltd | Hospitality | 2026 |
| CLO Pubs Ltd | Hospitality | 2019 |
| Cloathgate Limited | Real estate | 1976 |
| Clocek Ltd | Wholesale & retail | 2024 |
| Clock Tower (York) Management Company Limited | Real estate | 2022 |
| Clockworkation Ltd | Professional & scientific | 2025 |
| Clothes the Loop Ltd | Wholesale & retail | 2025 |
| Cloud 9 (Central) Ltd | Other services | 2023 |
| Cloud 9 Digital Ltd | Administrative & support | 2013 |
| Cloud 9 Funerals (East Midlands) Ltd | Financial services | 2020 |
| Cloud 9 Funerals (Hampshire) Ltd | Financial services | 2023 |
| Cloud 9 Funerals Ltd | Financial services | 2020 |
| Cloud 9 Holdings Ltd | Financial services | 2020 |
| Cloud 9 Transfers & Holidays Ltd | Transport & logistics | 2025 |
| Cloud Companies Ltd | Hospitality | 2019 |
| Cloud Electronics Holdings Limited | Professional & scientific | 2008 |
| Cloud Electronics Limited | Manufacturing | 1980 |
| Cloud Grid Ltd | Information & communication | 2025 |
| Cloud Kubed Ltd | Information & communication | 2021 |
| Cloud Nine Decor Limited | Arts & recreation | 2018 |
| Cloud Recruiting Software Limited | Information & communication | 2018 |