| Claudia Sabina Wellness Limited | Health & social care | 2022 |
| Claudio Chimienti Ltd | Information & communication | 2017 |
| Claudiu Tanase Ltd | Transport & logistics | 2019 |
| Claw App Ltd | Information & communication | 2023 |
| Claw N Disorder Ltd | Professional & scientific | 2025 |
| Clay Creators Derby Limited | Education | 2021 |
| Clay Creators Limited | Education | 2016 |
| Clay Creators Loughborough Limited | Education | 2024 |
| Clay Creators Manchester Limited | Education | 2025 |
| Clay Creators Retail Limited | Wholesale & retail | 2020 |
| Clay-Shooter Ltd | Wholesale & retail | 2023 |
| Claye Buildings Limited | Real estate | 2020 |
| Clayton Ecology Ltd | Professional & scientific | 2023 |
| Clayton Hunt Ltd | Professional & scientific | 2005 |
| Claytons Plumbing Limited | Water & waste | 2010 |
| Clayton’S Yard Limited | Hospitality | 2021 |
| CLB Performance Ltd | Other services | 2014 |
| CLC Projects Limited | Construction | 2023 |
| CLD Architecture Ltd | Professional & scientific | 2022 |
| CLE Events Ltd | Administrative & support | 2022 |
| Clea Innovations Ltd | Administrative & support | 2024 |
| Clean & Co Limited | Administrative & support | 2003 |
| Clean & More Ltd | Administrative & support | 2025 |
| Clean & Shine Specialist Cleaning Services Ltd | Administrative & support | 2024 |
| Clean Cladding Ltd | Administrative & support | 2024 |
| Clean Consulting Ltd | Professional & scientific | 2020 |
| Clean CUT Barbershop 28 Ltd | Other services | 2026 |
| Clean Excellence Limited | Administrative & support | 2021 |
| Clean Living Housekeeping Ltd | Administrative & support | 2019 |
| Clean Notts Limited | Other services | 2014 |
| Clean Pipe Renewables Ltd | Construction | 2025 |
| Clean Slate Roofing Limited | Construction | 2023 |
| Clean Sweep N Co Limited | Wholesale & retail | 2025 |
| Clean Thinking Ltd | Professional & scientific | 2020 |
| Clean Waste Limited | Water & waste | 2010 |
| Cleanfast&Go Limited | Administrative & support | 2025 |
| Cleaning & Environmental Solutions Ltd | Administrative & support | 2013 |
| Cleaning & Maintanance Ltd | Administrative & support | 2025 |
| Cleaning Buzau Limited | Administrative & support | 2025 |
| Cleaning Network Ltd | Administrative & support | 2020 |
| Cleankwest Ltd | Administrative & support | 2025 |
| Cleanmovesolutions Ltd | Administrative & support | 2024 |
| Cleanmyhome Ltd | Administrative & support | 2026 |
| Cleanpro Services Ltd | Administrative & support | 2025 |
| Cleansed Life Ltd | Construction | 2022 |
| Cleansing Cleans Ltd | Administrative & support | 2022 |
| Cleansmart Limited | Wholesale & retail | 2005 |
| Cleansmart Properties Limited | Real estate | 2018 |
| Cleansoft Ltd | Information & communication | 2025 |
| Cleantech Holdings Limited | Professional & scientific | 2017 |
| Clear and Bright Consultancy Limited | Extraterritorial | 2012 |
| Clear and Bright Limited | Professional & scientific | 2012 |
| Clear Brew Leic & Rutland Ltd | Administrative & support | 2018 |
| Clear Choice Mortgages Limited | Administrative & support | 2005 |
| Clear Crystal Consultancy Ltd | Professional & scientific | 2015 |
| Clear Direction Housing Community Interest Company | Hospitality | 2015 |
| Clear Momentum Ltd | Professional & scientific | 2026 |
| Clear Ocean Trade Ltd | Wholesale & retail | 2024 |
| Clear Rock Legal Ltd | Information & communication | 2026 |
| Clear Steps Divorce Coaching Ltd | Health & social care | 2025 |
| Clear Vision Counselling Ltd | Health & social care | 2020 |
| Clearance Flooring Ltd | Wholesale & retail | 2021 |
| Clearbrook Educational Psychology Ltd | Education | 2021 |
| Clearco Group Ltd | Water & waste | 2025 |
| Clearcut Safety Solutions Limited | Professional & scientific | 2026 |
| Clearer Hearingcare Ltd | Wholesale & retail | 2017 |
| Clearglaze (Midlands) Limited | Construction | 2011 |
| Clearglaze Conservatories Limited | Construction | 2012 |
| Clearing Cilcles Ltd | Information & communication | 2025 |
| Clearing Group Holdings Limited | Financial services | 2026 |
| Clearlane IT Ltd | Information & communication | 2023 |
| Clearlogic Consulting Limited | Information & communication | 2012 |
| Clearmark Solutions Limited | Professional & scientific | 2001 |
| Clearside Solutions Limited | Construction | 2020 |
| Clearstones Services UK London Limited | Other services | 2018 |
| Cleartone Nottingham Limited | Information & communication | 2014 |
| Clearvia Limited | Information & communication | 2016 |
| Clearwater Associates Ltd | Professional & scientific | 2015 |
| Clearway (Midlands) Limited | Other services | 2002 |
| Clearzone Property Assets Ltd | Construction | 2021 |
| Clegg Accommodation Solutions Limited | Construction | 2005 |
| Clegg Construction Limited | Construction | 1960 |
| Clegg EBT Limited | Administrative & support | 2017 |
| Clegg EOT Limited | Professional & scientific | 2021 |
| Clegg Food Projects Consultants Limited | Professional & scientific | 2012 |
| Clegg Food Projects Limited | Construction | 1998 |
| Clegg Group Limited | Professional & scientific | 1998 |
| Clegg Holdings Limited | Professional & scientific | 2007 |
| Clegg Homes Limited | Construction | 2003 |
| Clegg Nominees Limited | Administrative & support | 2007 |
| Clegg Small Projects Limited | Construction | 2005 |
| Clegg Special Projects Limited | Extraterritorial | 1997 |
| Clemelectrical Limited | Manufacturing | 2019 |
| Clement Ogilvie Limited | Health & social care | 2014 |
| Clement Pianos Limited | Manufacturing | 2007 |
| Clement’S Property Maintenance Ltd | Construction | 2025 |
| Clemfield Consulting Ltd | Information & communication | 2023 |
| Clemzoma Services Ltd | Health & social care | 2014 |
| Cleo Lacey Homes Limited | Real estate | 2024 |
| Cleos Cafe Ltd | Hospitality | 2021 |