| Northern Drainage Ltd | Leeds | 2025 |
| Northern Effluent Solutions Limited | North Shields | 2017 |
| Northern Fallen Stock Ltd | Workington | 2008 |
| Northern Ireland Water Alpha Limited | Crumlin | 2004 |
| Northern Ireland Water Limited | Belfast | 2005 |
| Northern Logistics Group Ltd | Sheffield | 2019 |
| Northern Pallet Management Limited | Bradford | 2021 |
| Northern Plasterboard Recycling Ltd | Bacup | 2018 |
| Northern Premier Solutions Ltd | Ilkley | 2024 |
| Northern Recycling & Waste Limited | Wilmslow | 2011 |
| Northern Recycling Co Ltd | Bradford | 2022 |
| Northern Recycling Solutions Ltd | Glasgow | 2008 |
| Northern Refine Ltd | Leeds | 2019 |
| Northern Resilience Ltd | Carlisle | 2025 |
| Northern Solutions Ltd | Middlesbrough | 2021 |
| Northern Trading (Cumbria) Limited | Penrith | 2008 |
| Northern Waste Management Ltd | Carlisle | 2014 |
| Northern Waste Recycling Ltd | Newton Aycliffe | 2016 |
| Northern Waste Solutions Ltd | Cleckheaton | 2026 |
| Northern Water Services Limited | Warrington | 2003 |
| Northern Way Services Limited | Accrington | 2026 |
| Northern Welsh Recycling Ltd | Porthmadog | 2015 |
| Northgate Waste Services Ltd | Witham | 2025 |
| Northstarmed GB Ltd | London | 2023 |
| Northtech Recycling & Aggregates Limited | Arbroath | 2025 |
| Northumberland Energy Recovery Ltd | Maidenhead | 2006 |
| Northumberland Waste Management Limited | Maidenhead | 1991 |
| Northumberland Waste Removals Ltd | Whitley Bay | 2026 |
| Northumbria Recycling Limited | Bedlington | 2007 |
| Northumbria Waste Recycling Ltd | Ashington | 2024 |
| Northumbrian Water Limited | Pity Me | 1989 |
| Northvg Ltd | Glasgow | 2015 |
| Northwest Asset Solutions Ltd | Bolton | 2026 |
| Northwest Drainage 24/7 Ltd | Bolton | 2026 |
| Northwest Waste and Garden Maintenance Ltd | London | 2026 |
| Northwestspecialistcleaning Limited | Liverpool | 2025 |
| Northwich Drain Unblocking Limited | Northwich | 2026 |
| Northwich Recycle and Demolition Ltd | Northwich | 2020 |
| Northwich Recycling & Demolition Limited | Rudheath, Northwich | 2019 |
| Northwood Recycling Limited | Stockport | 2009 |
| Norton Office Cleaning Ltd | Hereford | 2007 |
| Norven Polymers Ltd | Rugby | 2026 |
| Norvite,Limited | Sunderland | 1951 |
| Norwaste Environmental Limited | Liverpool | 2002 |
| Norwich Drain Services Ltd | Norwich | 2022 |
| Norwich Scrap Metals Ltd. | Norwich | 2016 |
| Norwich Waste Disposal Ltd | Norwich | 2016 |
| Norwood Construction Group Limited | Saffron Walden | 2021 |
| Norwood Metals Limited | Sheffield | 1997 |
| Norwood Waste Ltd | Liverpool | 2025 |
| Nosha Solutions Limited | Leeds | 2025 |
| NOT Waste Milverton CIC | Bromley | 2020 |
| Notec Ltd | Eastbourne | 2015 |
| Nott Contracting Limited | Birmingham | 2010 |
| Nottingham & Mansfield Drains Ltd | Mansfield | 2023 |
| Nottingham Recycling Limited | Coventry | 1996 |
| Nottingham Sleeper Company Limited | Retford,Notts. | 1965 |
| Nouvelle Generation Limited | London | 2020 |
| Nova Client Management Ltd | Redcar | 2025 |
| Nova Waste Management Ltd | London | 2025 |
| Novadumps Ltd | Glasgow | 2025 |
| Novareon Technologies Limited | London | 2024 |
| Novatech Services Limited | New Addington | 2006 |
| Novem Car Interior Design Limited | Cardiff | 1985 |
| Novum Waste Recycling Limited | Crewe | 2021 |
| Novus Business Consultants Limited | Melksham | 2020 |
| NOW Drainage & Plumbing Services Ltd | Bournemouth | 2024 |
| NOW! Charity Group Ltd | Lewes | 1995 |
| Nozama.Green Ltd | London | 2019 |
| NP Facilities Ltd | Enfield | 2021 |
| NP Niki Services Limited | Dagenham | 2019 |
| NPL Waste Management Holdings Ltd | Manchester | 2005 |
| NPL Waste Management Limited | Manchester | 2007 |
| NPT Waste Solutions Ltd | Cwmbran | 2010 |
| NPW Services Limited | Liss | 2015 |
| NRC Industrial Services Limited | Birkenhead | 2023 |
| NRG Environmental Ltd | Potters Bar | 2016 |
| NRG Powerjet Ltd | Hemel Hempstead | 2018 |
| NRJ Consultants Limited | Leamington Spa | 2014 |
| NRS Bancroft Aggregates Limited | Meriden | 2021 |
| Ns-Teck Limited | Darlington | 2025 |
| NSI Industrial O&M Solutions Ltd | Truro | 1990 |
| NSI Mobile Water Solutions UK Limited | Stoke On Trent | 2022 |
| NSI Water and Wastewater Solutions Ltd | Truro | 2003 |
| NTB Eco OIL Limited | Belfast | 2015 |
| Ntifo Enterprises Ltd | Croydon | 2018 |
| Ntsd Limited | Goudhurst | 2021 |
| Nuffield Salvage Co.Limited | Wallingford | 1960 |
| Nugen Recycling & Environmental Solutions Ltd | Broxburn | 2019 |
| Nugents Waste Management Services Limited | Bracknell | 2015 |
| Nulam Holdings Limited | London | 2026 |
| Nulam Technologies Limited | London | 2026 |
| Nunnery Stables (Management Company) Limited | Hertfordshire | 1982 |
| Nutrient Credits Limited | Tiverton | 2023 |
| Nuvia Limited | Warrington | 1986 |
| Nuwash Ltd | Walsall | 2021 |
| Nuwaste Ltd. | London | 2015 |
| NV Waste Management Ltd | London | 2023 |
| NVA Biotech Co Ltd | London | 2022 |
| NVP Energy UK Limited | Leigh-On-Sea | 2013 |