| Clean Air Monitoring Solutions Limited | Bridgend | 2023 |
| Clean Air Scotland Limited | Alexandria | 2017 |
| Clean Air Services Ltd | Chester | 2018 |
| Clean and Fresh Deeside Ltd | Aberdeen | 2023 |
| Clean and Shiny (UK) Limited | Aldershot | 2013 |
| Clean and Sparkling Ltd | Grays | 2026 |
| Clean and Wild Food Ltd | Braunton | 2026 |
| Clean Beauty Co Limited | Droitwich Spa | 2015 |
| Clean Bidco Limited | Bristol | 2019 |
| Clean Burner Systems Limited | Livingston | 2007 |
| Clean Carbon Limited | Livingston | 2021 |
| Clean Cell Technologies Ltd | London | 2019 |
| Clean Colour Ltd | London | 2024 |
| Clean Concrete UK Ltd | Bristol | 2021 |
| Clean Condiments Limited | Altrincham | 2020 |
| Clean Connect Group Ltd | London | 2026 |
| Clean Correct Ltd | London | 2026 |
| Clean Courts Ltd | Stamford | 2021 |
| Clean Cozy Ltd | London | 2025 |
| Clean Crops Farm Limited | Bicester | 2025 |
| Clean CUT Solar Services Ltd | Bridgnorth | 2020 |
| Clean Eats Direct Ltd | London | 2025 |
| Clean Energy (Scotland) Ltd | Kelso | 2022 |
| Clean Energy Design Systems Ltd | Stevenage | 2023 |
| Clean Energy Engineering Ltd | Darlington | 2018 |
| Clean Energy Maintenance Ltd | Essex | 2023 |
| Clean Energy Prospector Ltd | Bristol | 2008 |
| Clean Energy Services Limited | Market Drayton | 1999 |
| Clean Entry Locksmith Ltd | Wallington | 2026 |
| Clean Foods UK Meal Prep Limited | Paisley | 2017 |
| Clean Fuel Living Limited | Pulborough | 2025 |
| Clean Goat Co. Ltd | Caernarfon | 2025 |
| Clean Grid NI Ltd | Belfast | 2025 |
| Clean Hearted 24S Ltd | Erith | 2024 |
| Clean Image Hygiene Limited | Rochester | 2004 |
| Clean Immaculate Services Ltd | Stanmore | 2023 |
| Clean Lean Kitchen Ltd | Penarth | 2018 |
| Clean Meals and Fitness Ltd | London | 2026 |
| Clean Medical Ltd | Leatherhead | 2024 |
| Clean Midco Limited | Bristol | 2019 |
| Clean My DPF Ltd | Hounslow | 2026 |
| Clean N Go Ltd | Lochgelly | 2026 |
| Clean Packaging Ltd | Fowey | 2013 |
| Clean Paws Ltd | Borehamwood | 2022 |
| Clean Plastic Limited | London | 2023 |
| Clean Plastic Mouldings Limited | Wetherby | 1960 |
| Clean Power Hydrogen Group Limited | Doncaster | 2016 |
| Clean Power Systems (UK) Limited | Cambridge | 2024 |
| Clean Propulsion Technologies Limited | Exeter | 2024 |
| Clean Rebuild Limited | Glasgow | 2020 |
| Clean Sciences Limited | Leeds | 2012 |
| Clean Seas Technologies Ltd | Brecon | 2018 |
| Clean Skies Limited | London | 2017 |
| Clean Structures (UK) Ltd | Wotton-Under-Edge | 2006 |
| Clean Tech U.K. Limited | Hemswell | 2016 |
| Clean Topco Limited | Bristol | 2019 |
| Clean Water for Homes Ltd | Londonderry | 2022 |
| Clean Wine Limited | Wilmslow | 2020 |
| Clean With Green Ltd | Leicester | 2023 |
| Clean Your Kicks BRO Ltd | London | 2026 |
| Cleanacres Machinery Limited | Cheltenham | 1978 |
| Cleanair Products and Services Limited | Watford | 2024 |
| Cleanar LUX House Ltd | London | 2025 |
| Cleanaura Solutions Limited | Skelmersdale | 2025 |
| Cleanbite Limited | Cardiff | 2016 |
| Cleanbyot Ltd | London | 2024 |
| Cleandynamic Athletica Ltd. | Dagenham | 2025 |
| Cleaner Seas Group Limited | Bude | 2018 |
| Cleangrip Limited | Leamington Spa | 2018 |
| Cleaning Dept Ltd | Smethwick | 2026 |
| Cleaning Equipment Sales and Services Limited | London | 2024 |
| Cleaning Lords Ltd | Middlesbrough | 2026 |
| Cleaning Machinery (K.E.W.) Limited | Somerset. | 1986 |
| Cleaning Supplies Cardiff Limited | Cowbridge | 1971 |
| Cleaning Sweep Ltd | London | 2026 |
| Cleanline Creative Limited | Rugby | 2020 |
| Cleanliness Ltd | Leicester | 2001 |
| Cleanlynk Ltd | Telford | 2025 |
| Cleanological Ltd | London | 2024 |
| Cleanpie Biological Technology Co., Ltd | Evesham | 2022 |
| Cleanprepkitchen Limited | Newcastle Upon Tyne | 2021 |
| Cleanr House and Flants Ltd | London | 2025 |
| Cleanroom Furniture Limited | Rossendale | 2025 |
| Cleanroom Projects Limited | Rossendale | 2007 |
| Cleanrooms Solutions Limited | Manchester | 2024 |
| Cleanse-Oil Limited | Plymouth | 2015 |
| Cleanshet Ltd | Harrow | 2023 |
| Cleansubsea UK Limited | Liverpool | 2025 |
| Cleansup Limited | London | 2025 |
| Cleantec Appliance Services Ltd | Rochdale | 2022 |
| Cleantech Gulf Global Ltd | Ruislip, | 2025 |
| Cleanux Chemicals Ltd | Waltham Abbey | 2017 |
| Cleanwell High Pressure Washers Limited | Kents Avenue Hemel Hempstead | 1983 |
| Cleanwind Ltd | Argyll | 2010 |
| Cleanwright Limited | Mansfield | 2001 |
| Clear 'N' Collect Ltd | Ascot | 2019 |
| Clear - Seal Limited | Aston | 1990 |
| Clear Air Technology Limited | Halifax | 2020 |
| Clear and Clean (Bristol) Limited | Hereford | 2019 |
| Clear Audio Systems Ltd | Glenrothes | 1993 |