| Comfort Water Treatment Limited | Witham | 2016 |
| Comfy Direct Limited | London | 1996 |
| Commercial Alloys Batteries & Residues Limited | London | 2019 |
| Commercial Domestic Rubbish Glasgow Limited | Glasgow | 2021 |
| Commercial Drainage Services (Essex) Ltd | Basildon | 2017 |
| Commercial Drainage Services Limited | Basildon | 2018 |
| Commercial Environmental Services Ltd | Fair Oak | 2024 |
| Commercial Industrial Cleaning Services Ltd | Bradford | 2024 |
| Commercial IT Recycling Ltd | Nottingham | 2017 |
| Commercial Recycling (Southern) Limited | Wimborne | 2008 |
| Commercial Recycling Ltd | London | 2020 |
| Commercial Recycling Solutions Ltd | London | 2026 |
| Commercial Scrap Solutions Ltd | Huddersfield | 2020 |
| Commercial Services Kent Limited | West Malling | 2006 |
| Commercial Trading & Engineering Ltd | Ruislip | 2023 |
| Commercial Vehicle Roofs Limited | Manchester | 1974 |
| Commercial Waste and Recycling Ltd | London | 2014 |
| Commercial Waste Clearance Ltd | Huddersfield | 2025 |
| Commercial Waste Management Ltd | Bristol | 2025 |
| Commercial Waste Recycling Limited | Leicester | 2012 |
| Commercial Waste Solutions Ltd | Bristol | 2025 |
| Commercial Water Solutions Ltd | Edinburgh | 2006 |
| Commercialbincleaningg Ltd | London | 2024 |
| Commissioning Services (South East) Limited | Cardiff | 2019 |
| Commodity Creations Ltd | Nottingham | 2017 |
| Commodity Metal Exchange Ltd | Wembley | 2024 |
| Community Metal Recycling CIC | London | 2022 |
| Community Minibuses Limited | Newcastle Upon Tyne | 2000 |
| Community Transport | Newcastle Upon Tyne | 1987 |
| Compact and Bale Limited | Sittingbourne | 2000 |
| Compact Cases Limited | Maidenhead | 1965 |
| Companion Clearance Limited | Thornton Heath | 2023 |
| Compass DUE North Ltd | Nottingham | 2021 |
| Compass Environmental Services Limited | Durham | 2014 |
| Compass Skip Hire Ltd | London | 2019 |
| Complete Auto Recycling Ltd | London | 2025 |
| Complete Biohazard & Trauma Cleaning Ltd | Hinckley | 2022 |
| Complete Clearances (North West) Ltd | Chester | 2021 |
| Complete Consultant Services Ltd | London | 2026 |
| Complete Drain Services Limited | Burnley | 2002 |
| Complete Drainage Norfolk Ltd | Norwich | 2026 |
| Complete Drainage Solutions Ltd | Liphook | 2014 |
| Complete Industrial Cleaning Ltd | Wilmslow | 2023 |
| Complete Metal Recycling Limited | Willenhall | 2014 |
| Complete Pools and Leisure Ltd | Bangor | 2018 |
| Complete Remediation Solutions Limited | Stanmore | 2025 |
| Complete Rubbish Ltd | Maidenhead | 2020 |
| Complete Sewer Connections Ltd | Stockbridge | 2017 |
| Complete Shredding Limited | Newcastle Upon Tyne | 2022 |
| Complete Washroom Solutions Limited | Coventry | 2004 |
| Complete Waste Management Ltd | Leigh-On-Sea | 2023 |
| Complete Waste Services London Ltd | Loughton | 2019 |
| Complete Wasters Limited | Loughborough | 1997 |
| Complete Water Care Ltd | London | 2022 |
| Complete Water Solutions UK Ltd | Chandler'S Ford | 2005 |
| Complete Water Treatment Ltd | Conlig | 2018 |
| Complete Wood Recycling Ltd | Dudley | 2021 |
| Completed Services Limited | Brentwood | 2022 |
| Completely Clear Limited | Wickford | 2017 |
| Complex Waste Solutions Ltd. | Ashford | 2025 |
| Compli Digital Ltd | Mansfield | 2025 |
| Compliance Management Group Ltd | Craigavon | 2016 |
| Compliant Asbestos Removal Ltd | Adlington | 2019 |
| Compliant Water Solutions Ltd | Liverpool | 2019 |
| Compliant Water Systems Ltd | London | 2018 |
| Complycycle Ltd | London | 2025 |
| Compost Club Ltd | Heathfield | 2021 |
| Compost Collective CIC | Crediton | 2024 |
| Compost Mentis Limited | Braunton | 2021 |
| Compost Works (UK) Ltd | Liverpool | 2019 |
| Compostator Ltd | London | 2020 |
| Computer Salvage Specialists (Special Waste) Limited | Newbury | 2001 |
| Computer Waste Recycling Ltd | Leicester | 2024 |
| Computex Recycling Ltd | Maidstone | 2025 |
| Concept Environmental Solutions Limited | Manchester | 2013 |
| Concept Waste Management (SW) Limited | Torquay | 2025 |
| Concept Waste Management Limited | Sutton | 2013 |
| Concept Waste Solutions Ltd | Chichester | 2019 |
| Concorde Plant and Waste Ltd | Glasgow | 2019 |
| Concorde Sign Company Limited | Brodick | 1999 |
| Conder Environmental Solutions Ltd | Weybridge | 1969 |
| Confidential Document Destruction Limited | Sheerness | 2017 |
| Confidential Information Destruction Limited | Rotherham | 2001 |
| Confidential Services Ireland Limited | Londonderry | 2015 |
| Confidential Waste Solutions Limited | Woodhall Spa | 2014 |
| Confined Space Group Ltd | London | 2024 |
| Confluency AI Ltd | London | 2026 |
| Connected Waste Management Ltd | St. Albans | 2024 |
| Connell Brothers Demolition Limited | Salford, Manchester | 2007 |
| Connex Digital Limited | Harpenden | 2024 |
| Conqueror Refuse and Waste Ltd | Hastings | 2021 |
| Conro and Sons Environmental Solutions Ltd | Shrewsbury | 2025 |
| Conroy's Recycling Limited | Skegness | 2008 |
| Conscruit Construction Limited | London | 2024 |
| Consensus Facilities Management Ltd | Wembley | 2025 |
| Conservaqua Limited | Leatherhead | 2019 |
| Conserve Hygiene Ltd | Eastleigh | 2016 |
| Considered Cleaner Ltd | Orpington | 2023 |
| Consolidated Logistics Services Limited | Feltham | 2008 |
| Constant Hygiene Limited | Lingfield | 2007 |