| Cyfarthfa Structures Limited | Merthyr Tydfil | 2007 |
| Cygnet Laboratory Furniture Limited | Mosley Street | 1951 |
| Cygnet P. F. & F. Limited | | 1994 |
| Cymru LAN Cyfyngedig | Gaerwen | 2002 |
| CYN Organics Ltd | Wigan | 2019 |
| Cynon Valley Waste Disposal Company Limited | Rhondda Cynon Taff | 1991 |
| Cynosure Partners Ltd | Broadstone | 2018 |
| Cysgod-Y-Gaer Management Company Limited | Lampeter | 2007 |
| CZ & Sons Limited | Bishops Stortford | 2025 |
| D & B Remediation Limited | Nantwich | 2011 |
| D & B Supplies Limited | Leeds | 2015 |
| D & E Scrap Metals Limited | Newport | 2012 |
| D & J Rubbish Removal Limited | Staines-Upon-Thames | 2014 |
| D & K (East Scotland) Limited | Glasgow | 2015 |
| D & L Contract Services Limited | Luton | 2010 |
| D & M Leftly & Sons Ltd | Canvey Island | 2007 |
| D & M Recycling & Waste Management Limited | Bicester | 2002 |
| D & M Tankers Ltd | Leicestershire | 2007 |
| D & P Paper Recycling Ltd | West Bromwich | 2024 |
| D & P Waste Paper & Plastic Recycling Limited | Wolverhampton | 1995 |
| D & S Drainage Limited | King'S Lynn | 2013 |
| D & S Metals Ltd | Wednesbury | 2011 |
| D & S Valeting and Detailing Services Limited | London | 2022 |
| D & T Rubbish & Rubble Limited | Blackpool | 2023 |
| D & T Waste Ltd | London | 2025 |
| D a Culling Scrap Metals Ltd. | Norwich | 2017 |
| D a Tippers Ltd | Potters Bar | 2025 |
| D and a Services Chesterfield Limited | Chesterfield | 2007 |
| D and B Utilities Limited | Oswestry | 2007 |
| D B Waterworks Limited | Telford | 2014 |
| D Best Waste Limited | Loughton | 2024 |
| D D (Outwell) Limited | Downham Market | 2015 |
| D D E Remediation Solutions Limited | Cleethorpes | 2025 |
| D Deep Cleaning Services Ltd | Accrington | 2021 |
| D E G Simpson & Sons Limited | Buntingford | 2016 |
| D F Stewart Services Limited | Corby | 2002 |
| D H Traders Limited | Bradford | 2019 |
| D Harrison and Sons Ltd | Nottingham | 2020 |
| D Hughes Demolition & Excavation Limited | Altrincham | 1998 |
| D J Cleaning Limited | York | 2002 |
| D J Haulage Kilsyth Limited | Glasgow | 2019 |
| D J Hinton & Co Limited | Kidderminster | 2002 |
| D J Laing Recycling Solutions Limited | Carnoustie | 2011 |
| D J Recycling Ltd | Worthing | 2022 |
| D J S Waste Ltd | Manchester | 2024 |
| D J Tippers & Grab Hire Limited | Dagenham | 2013 |
| D K Remediation Ltd | Londonderry | 2011 |
| D L Hughes Limited | Conwy | 2001 |
| D L T Waste Water Treatment Ltd | Herefordshire | 2007 |
| D Lloyd Jones Plumbing & Heating Ltd | Oswestry | 2012 |
| D M Boyles Limited | Market Rasen | 2003 |
| D M Drainage Ltd | Braintree | 2013 |
| D N R Maintenance Ltd | Harrow | 2020 |
| D O'Keefe Limited | Ilford | 2019 |
| D P Newton Limited | St. Albans | 2021 |
| D R Brown Contracts Ltd | Dereham | 2022 |
| D Robinson & Co Limited | Desborough | 2012 |
| D S Cooper Limited | Shelley | 1940 |
| D S Waste Limited | Luton | 2023 |
| D Sheps Ltd | Chigwell | 2014 |
| D Vaughan Waste Services Limited | Swalwell | 2024 |
| D W P (Recycling) Limited | Swanley Village | 2005 |
| D Weatheritt Plumbing Services Limited | Norwich | 2016 |
| D&A Water Hygiene Solutions Ltd | Broadstairs | 2024 |
| D&D Removals & Logistics Ltd | Crawley | 2025 |
| D&H Property Solutions Ltd | Benfleet | 2026 |
| D&L 86 Limited | Motherwell | 2025 |
| D&L Recycling Ltd | Hemel Hempstead | 2023 |
| D&L Waste Ltd | Feltham | 2025 |
| D&M Asbestos Removal Ltd | Stourbridge | 2024 |
| D&P Industrial Services Limited | Pontefract | 2025 |
| D&P Removals Ltd | London | 2017 |
| D&R Drain Services Limited | Ruislip | 2015 |
| D&S Clean and Clear Ltd | Brecon | 2023 |
| D&S Services (SW) Ltd | Cheddar | 2016 |
| D&S Skips Limited | Ilford | 2017 |
| D&S Waste Management Ltd | Walsall | 2025 |
| D&S Waste Recycling Ltd | Rainham | 2023 |
| D&T Investments Limited | Milton Keynes | 2007 |
| D&T Waste Solutions Limited | Ivybridge | 2026 |
| D. Body Limited | Rochester | 2007 |
| D. C. Drains Ltd | Lisburn | 2017 |
| D. Haird & Company Limited | Newmarket | 1974 |
| D. Howell & Sons Limited | Keston | 2011 |
| D. M. R. Recycled Autoparts Limited | Northampton | 1975 |
| D.B Clearances Ltd | Swanley | 2021 |
| D.E.M.C.O Asbestos Removal and Demolition Limited | Morecambe | 2024 |
| D.F.C. Water Services Ltd | Manchester | 2010 |
| D.H.A. Pollution Control Ltd. | Bristol | 1997 |
| D.Harrison (U.K) Limited | Nottingham | 2013 |
| D.I. Evans Cyfyngedig | Dyfed | 2001 |
| D.L.H. Autorecyclers Limited | Norwich | 2007 |
| D.M Drainage & Property Solutions Ltd | London | 2025 |
| D.M.E. Tyres Limited | Lichfield | 2005 |
| D.N.A. Reynolds Services Limited | Attleborough | 2013 |
| D.P. Skip Hire Limited | Newcastle-Under-Lyme | 1995 |
| D.R Water Ltd | Cannock | 2024 |
| D.R.F Waste Removals Limited | Neath | 2025 |
| D.S.M. Asbestos Consultants Ltd | London | 2006 |
| D.Z.H Environmental Services Ltd | Basildon | 2021 |