| Clarkes of Melton Ltd | Nr Rushden | 2006 |
| Clarkes UK Drainage Specialists Limited | Spalding | 2024 |
| CLARKES.RECOVERY247 Ltd | Birmingham | 2017 |
| Clarkeson Recycling Limited | Grimsby | 2006 |
| Clarks Advanced Shredding Limited | Sudbury | 2009 |
| Clarkson Waste Ltd | London | 2026 |
| Clas Haulage Limited | Rotherham | 2017 |
| Class a Property Solutions Ltd | Canvey Island | 2025 |
| Clauscarsaleandrecovery Limited | Peterborough | 2025 |
| Claverdon Salvage and Parts Ltd | Coventry | 2024 |
| Clay Cross Land Limited | Bourne | 2006 |
| Clay Flatts Autospares Limited | Cumbria | 2003 |
| Claydon Skip Hire Ltd | Ipswich | 2006 |
| Claymead Limited | London | 1993 |
| Clays Wood Reclamation Limited | Lydney | 1980 |
| Clayton Waste Services Ltd | Acocks Green | 2019 |
| Claytons Plumbing Limited | Nottingham | 2010 |
| CLC Recycling Services Limited | Penrith | 2023 |
| Clean & Carry Ltd | London | 2026 |
| Clean & Clear Southern Ltd | Portsmouth | 2019 |
| Clean 365 Limited | Chester | 2009 |
| Clean 4 Today Limited | Waltham Abbey | 2017 |
| Clean a Drain Ltd | Newcastle | 2021 |
| Clean Air Roads Limited | Cardiff | 2017 |
| Clean and Green Preston Limited | Preston | 2025 |
| Clean and Serene Ltd | Billericay | 2013 |
| Clean Co Waste Removals Ltd | Barry | 2025 |
| Clean Drain Limited | Chelmsford | 1980 |
| Clean Earth Waste Solutions Ltd | Rushden | 2025 |
| Clean Flow Water Limited | Leeds | 2010 |
| Clean GAS Technologies Ltd | Sutton Coldfield | 2012 |
| Clean Green Recycling Ltd | Saltburn-By-The-Sea | 2014 |
| Clean Green Waste Limited | London | 2019 |
| Clean Ground Solutions Ltd | London | 2023 |
| Clean Island Limited | Fareham | 2016 |
| Clean IT Cardiff Rubbish Removals and Recycling Ltd | Cardiff | 2021 |
| Clean Machine and Clearance Limited | Sheffield | 2020 |
| Clean My Waste Ltd | Bolton | 2024 |
| Clean Nation Ltd | Loughton | 2010 |
| Clean OUR Oceans Limited | Ascot | 2018 |
| Clean PAK Limited | Normanton | 2012 |
| Clean Planet Northwest Ltd | Bolton | 2024 |
| Clean Planet Recycling Ltd | Acton | 2024 |
| Clean Planet Teesside Ltd | London | 2020 |
| Clean Slate Disposal Ltd | London | 2024 |
| Clean Slate SW Ltd | Plymouth | 2025 |
| Clean Sweep (Cheshire) Limited | Crewe | 2011 |
| Clean Waste Limited | Nottingham | 2010 |
| Clean Waste Services Ltd | Hexham | 2018 |
| Clean Water International (UK) Limited | Swaffham | 2007 |
| Clean Water International Limited | Swaffham | 2004 |
| Clean Water Services Ltd | Tamworth | 2015 |
| Clean Water Wave C.I.C. | Edinburgh | 2017 |
| Clean Your Junk Ltd | London | 2025 |
| CLEAN4ALL Ltd | Rochester | 2025 |
| CLEAN4GREEN Ltd | Barnet | 2024 |
| Cleanbuild Environmental Contractors Ltd | Coventry | 2026 |
| Cleanco (Highland) Holdings Ltd | Inverness | 2021 |
| Cleancyclers Limited | Enfield | 2023 |
| Cleandust Ltd | Plymouth | 2019 |
| Cleaned UP London Limited | London | 2024 |
| Cleaners Management Ltd | London | 2025 |
| Cleaners World Limited | Canvey Island | 2016 |
| Cleaning Champions Limited | Bedworth | 2016 |
| Cleaning Roofs, Garden and Waste Collection Limited | Leicester | 2022 |
| Cleanmet Limited | Halifax | 1964 |
| Cleanngreen Waste Ltd | Norwich | 2025 |
| Cleanscape Waste and Hygiene Ltd | Didcot | 2026 |
| Cleansing Service Group (Recovery) Limited | Fareham | 1962 |
| Cleansing Service Group (Wilton) Limited | Fareham | 2010 |
| Cleansweepsolutionscss Ltd | Dudley | 2024 |
| Cleantank Limited | Normanton | 2010 |
| Clear & Recycle Ltd | Surbiton | 2021 |
| Clear - Stream Drainage Solutions Ltd | Falmouth | 2024 |
| Clear 365 Limited | London | 2025 |
| Clear a Space EA Ltd | Snetterton | 2025 |
| Clear ALL Limited | Lichfield | 2026 |
| Clear and Clean (Clacton) Ltd | Leigh-On-Sea | 2025 |
| Clear and Clean (Sussex) Ltd | Brighton | 2025 |
| Clear and Clean House Clearance Ltd | Gloucester | 2025 |
| Clear and Go Limited | Hayes | 2024 |
| Clear and Go Skips Limited | Reading | 2021 |
| Clear Away Junk Ltd | London | 2025 |
| Clear Balance Debt Recovery Ltd | Dartford | 2026 |
| Clear Boss Waste Limited | Gravesend | 2026 |
| Clear Business Water Limited | Glasgow | 2013 |
| Clear Clog Ltd | West Malling | 2025 |
| Clear Conscience Ltd | Farnham | 2025 |
| Clear Direction Consulting Ltd | Redditch | 2025 |
| Clear Drain (North East) Ltd | Durham | 2022 |
| Clear Drain Services Limited | Ellesmere Port | 2010 |
| Clear Drain Solutions Group Ltd | Christchurch | 2025 |
| Clear Drain Solutions Ltd | Christchurch | 2024 |
| Clear Drainage Solutions Ltd | Congleton | 2024 |
| Clear Drains Drainage and Plumbing Ltd | Cheadle | 2017 |
| Clear Drains Northwest Limited | Warrington | 2020 |
| Clear Earth Management Ltd | Torquay | 2019 |
| Clear Environmental Services Limited | Cheshire | 2011 |
| Clear Flow Water Limited | Meopham | 2023 |
| Clear Flow Water Solutions Limited | London | 2012 |