| Constone Facility Management Ltd | Aberdeen | 2025 |
| Construction & Civil Site Services Ltd | Southampton | 2011 |
| Construction Builders Clean Ltd | Birmingham | 2020 |
| Construction Recycling Services Limited | Rochdale | 2008 |
| Construction Resource Recycling Ltd | Loughton | 2025 |
| Construction Waste Services Limited | Birmingham | 2022 |
| Constructive Recycling Ltd | Canvey Island | 2012 |
| Constructo 7 Limited | Nantwich | 2024 |
| Consulting Building Service Limited | London | 2015 |
| Container Fumigation Services Limited | Southampton | 2003 |
| Containment Logic Limited | Orpington | 2025 |
| Contaminant Removal Solutions Ltd | Holmfirth | 2022 |
| Contemporary Tech Solutions Ltd | Harrow | 2026 |
| Continuous Waste Management Ltd | Kent | 2004 |
| Contract Services DGN Ltd | Dungannon | 2006 |
| Contract Waste Management Limited | Isleworth | 2022 |
| Control Pollution Limited | Newhaven | 2011 |
| Convert Recycling Ltd | London | 2003 |
| Convert Water Limited | Hertford | 2015 |
| Converter Limited | Liverpool | 2020 |
| Conway Operations Ltd | Lees | 2026 |
| Conway Traders Limited | Mitcheldean | 2025 |
| Cookham Waste Ltd | London | 2021 |
| Cooks Wastekare Ltd | Stowmarket | 2000 |
| Cooksey Reclamation Limited | Dudley | 2002 |
| Cookswood Utilities Ltd | Glastonbury | 2026 |
| Cool Munchkin Ltd | High Wycombe | 2014 |
| Cooler Options Limited | Crewe | 2014 |
| Cooper Holdings Group Limited | Solihull | 2019 |
| Cooper Skip Hire Limited | West Byfleet | 2013 |
| Cooper Specialist Groundworks Ltd | Solihull | 2016 |
| Cooperm Home Improvements Limited | Peterborough | 2020 |
| Coopers Recycling Limited | Cannock | 2018 |
| Coopers Waste Ltd | Edgbaston | 2021 |
| Coopers Waste Management Services (Staffordshire) Limited | Stafford | 2018 |
| Copia Metals Limited | Orpington | 2017 |
| Copia Metals London Ltd | Dartford | 2019 |
| Copia Recycling Ltd | Dartford | 2019 |
| Coporod Ltd | Walsall | 2026 |
| Copper Matters Limited | Tunbridge Wells | 2025 |
| Coprec Ltd | Ruislip, | 2025 |
| Coraxe Cleaning Services Ltd | Ongar | 2023 |
| Corby (Northants) and District Water Company Limited | London | 2016 |
| Core Clean Ltd | Heanor | 2020 |
| Core Fusion Limited | Colchester | 2010 |
| Core Fusion Recycling Limited | Colchester | 2022 |
| Core Values Services Ltd | Swadlincote | 2021 |
| Core Waste Management Ltd | Cardiff | 2020 |
| Core Water Solutions Limited | Okehampton | 2026 |
| Coredwell Ltd | Birmingham | 2026 |
| Cores Environment UK Limited | London | 2016 |
| Corguard Ltd | London | 2018 |
| Cornbrook Metal Recycling Limited | Manchester | 2003 |
| Cornelsen Limited | Bristol | 2003 |
| Corner Stone Group Property Solutions UK Ltd | London | 2025 |
| Corner Traders Limited | London | 2025 |
| Cornhill Environmental Solutions Ltd | Porthmadog | 2005 |
| Cornish Grab Co Ltd | Plymouth | 2024 |
| Cornwall Computers and Tech CIC | Truro | 2026 |
| Cornwall Cullet Limited | Redruth | 2009 |
| Cornwall Drains Ltd | Penzance | 2016 |
| Cornwall Energy Recovery Ltd | Maidenhead | 2006 |
| Cornwall Plastic Recycling Ltd | Bodmin | 2019 |
| Cornwall Skip Hire Ltd | Bexley | 2026 |
| Cornwall Waste Care Ltd. | Truro | 2018 |
| Cornwall Waste Solutions Limited | St. Austell | 2016 |
| Corporations Cleaning Limited | Leeds | 2016 |
| Corrie Skips Limited | Bo'Ness | 2022 |
| Corsham Waste Collections Limited | Chippenham | 2022 |
| Cortec (MRS) Ltd | Cranbrook | 2018 |
| Cory Barking Operations Limited | London | 1981 |
| Cory Environmental Limited | London | 1896 |
| Coseley Resources Ltd | Bilston | 2025 |
| Cosmic Waste Management Ltd | Dartford | 2024 |
| Cosmy Solutions Ltd | London | 2025 |
| Cosy Window Cleaning Ltd | Poole | 2018 |
| Cotooclean Ltd | London | 2021 |
| Cotswold Clearance Ltd | Swindon | 2022 |
| Cotswold Drain Services Limited | Staverton | 1998 |
| Cotswold Grab Hire Ltd | Gloucester | 2019 |
| Cotswold Recycling Company Limited | Bristol | 2001 |
| Cotswold Waste Limited | Chipping Norton | 2024 |
| Cotton Skips Ltd | Leamington Spa | 2026 |
| Cottonopoly Ltd | Manchester | 2023 |
| Couly Exports Ltd | Cardiff | 2016 |
| Country Clearance Ltd | Dorchester | 2020 |
| Country Compost Limited | Northwood | 2000 |
| Country Life Upholstery Limited | | 1983 |
| Country Mini Skips Ltd | Bradford On Avon | 2016 |
| Countrystyle Group Limited | Ashford | 2006 |
| Countrystyle Recycling Limited | Sittingbourne | 2004 |
| Countrywide Metals Ltd | Coventry | 2020 |
| County Cleansing Limited | Newton Abbot | 2003 |
| County Clearance Limited | Gloucester | 2014 |
| County Drain Care Ltd | Ferndown | 2018 |
| County Drain Services Limited | Cheltenham | 2022 |
| County Drains Maintenance Limited | Whaley Bridge | 2020 |
| County Durham Furniture Help Scheme | Ferryhill | 2005 |
| County Skip Hire Limited | Exeter | 1999 |
| County Tyre Recycling Ltd | Winchcombe | 2025 |