| Norway Enpfon International Ltd | Beckenham | 2023 |
| Norway Gwatt International Group Co., Ltd | Cambridge | 2026 |
| Norway Heterun Agricultural Chemical Co., Ltd | Cambridge | 2025 |
| Norway Ipsen Crop Nutrition Co., Ltd | Cambridge | 2026 |
| Norway Karo Crop Science Co., Ltd | Cardiff | 2024 |
| Norway Montreux Fertilizer Ltd | Coventry | 2025 |
| Norway Oprun International Group Co., Ltd | Cambridge | 2026 |
| Norway Osland Plant Nutrition Technology Limited | London | 2024 |
| Norway Oslo Crop Nutrition Co., Ltd | West Midlands, England | 2025 |
| Norway Ranhua Technology Group Co., Ltd | Beckenham | 2024 |
| Norway Saran (USA) Biotechnology Ltd | Cambridge | 2021 |
| Norway Tenmeira Industrial Co., Ltd | Cardiff | 2023 |
| Norway Yabote Chemical Co., Ltd | Cambridge | 2026 |
| Norway Yala Plant Nutrition Co., Ltd | Cardiff | 2026 |
| Norwegian Caribbean International Chemical Co., Ltd | Cambridge | 2026 |
| Norwegian Europeanization Group Ltd | Coventry | 2025 |
| Norwegian Redef Chemical Co., Ltd. | Cambridge | 2026 |
| Norwegian Romdt Chemical Stock Co., Ltd | Cardiff | 2026 |
| Norwegian Tenran Crop Nutrition Co., Ltd | Cambridge | 2026 |
| Norwegian Wagrella Plant Nutrition Technology Co., Ltd | Coventry | 2025 |
| Norwegian Wujikang Fertilizer Ltd | West Midlands, England | 2026 |
| Nostrum OIL & GAS Holding Limited | London | 2022 |
| Nostrum OIL & GAS PLC | London | 2013 |
| NOV Downhole Eurasia Limited | Stonehouse | 2002 |
| Novam Services Ltd | Washington | 2025 |
| Novas Logistics Limited | Stirling | 2024 |
| Novastar Energy Holdings Limited | London | 2023 |
| Novus UK (Indonesian Holdings) Limited | London | 1926 |
| Novus UK (Kakap) Limited | London | 1961 |
| Nozcorp Limited | Ellon | 2017 |
| Nqutu Consulting Ltd | Crymych | 2018 |
| NRC (Non-Ferro Recovery Company) UK Ltd. | Exeter | 2022 |
| NRG Consultancy Limited | Aberdeen | 2008 |
| NRG Well Examination Ltd | Aberdeen | 1998 |
| NRG Well Management Limited | Aberdeen | 2007 |
| Nrlc Ltd | High Wycombe | 2025 |
| NRN Glasgow Ltd | Glasgow | 2017 |
| NRS Bromsgrove Aggregates Limited | Meriden | 2020 |
| NRS Kidderminster Aggregates Limited | Meriden | 2018 |
| NRS Meriden Aggregates Ltd | Meriden | 2019 |
| NRS Saredon Aggregates Limited | Meriden | 2013 |
| NRS Woodcote Aggregates Ltd | Meriden | 2017 |
| NS Investments One (UK) Limited | Weybridge | 2022 |
| NS London Ltd | Loughton | 2017 |
| Nsic Ltd | Great Yarmouth | 2014 |
| Nsmp Operations Limited | London | 2015 |
| Nsnr Holding 1 Limited | Dorking | 2025 |
| NSQ Scotland Limited | Glasgow | 2017 |
| Ntaka Nickel Holdings Limited | London | 2015 |
| Nubian Gold Exploration Limited | London | 2011 |
| Nubian Shield Resources Ltd | Bristol | 2026 |
| Nucleus Energy Ltd | Peterhead | 2025 |
| Nucore Group Ltd. | Aberdeen | 2013 |
| NWP Minerals Limited | Witham | 2018 |
| NXG Drilling Services Limited | Aberdeen | 2016 |
| NXG International Limited | Aberdeen | 2017 |
| NXG Oilfield Services Limited | Aberdeen | 2017 |
| Nylish Ltd | Sutton | 2022 |
| O G F Plumbing and GAS Ltd | Longfield | 2025 |
| O&V&H Ltd | London | 2023 |
| O'Boyle Mining Ltd | London | 2019 |
| O'Brien Aggregate Marsden Limited | Whitburn | 2017 |
| O'Broin Offshore Services Limited | Aberdeen | 2010 |
| O'Jay OIL and GAS Ltd | Nottingham | 2025 |
| O'Kane Equipment Solutions Ltd | Larbert | 2018 |
| O'Sullivan Resources Limited | Norwich | 2008 |
| O.F.M Services Ltd | Newbridge | 2025 |
| Oak Tree (Aberdeen) Limited | Westhill | 2018 |
| Oakdale Garage Limited | Wakefield | 2004 |
| Oakesy Lifting and Rigging Services Ltd | Hull | 2018 |
| Oasis Petroleum Exploration Consultants Limited | Helston | 2000 |
| OBL Aggregates & Excavation Limited | Cleckheaton | 2016 |
| OBM Engineering Services Limited | Bathgate | 2018 |
| Obnisha Limited | Leicester | 2024 |
| Obsidian Resources Limited | Aberdeen | 2006 |
| Occw (Damside) Limited | Durham | 2013 |
| Ocea Energy UK Limited | London | 2023 |
| Ocean AID Medics Ltd | Bridport | 2024 |
| Ocean Blocks and Aggregates Ltd | Nuneaton | 2015 |
| Ocean Diamonds Limited | Falmouth | 2004 |
| Ocean Frontier Services Limited | Inverurie | 2000 |
| Ocean Installer Crewing Limited | Aberdeen | 2012 |
| Ocean Installer Limited | Aberdeen | 2012 |
| Ocean Installer Surf UK Limited | Aberdeen | 2013 |
| Ocean Minerals (SW) Ltd | St. Austell | 2015 |
| Ocean Reef Consulting Ltd | Hull | 2022 |
| Ocean Volt Services Ltd | Wolverhampton | 2025 |
| Oceangrove Geoscience Limited | Glasgow | 1994 |
| Oceanic Trading Limited | | 2004 |
| Oceanographic Technical Services Ltd | Peterhead | 2014 |
| Oceanport Trading International Limited | Bracknell | 2013 |
| Oceansteer Marine Services Limited | Fleetwood | 2018 |
| Oceantechnic Limited | Aberdeen | 2025 |
| OCH Electrical Ltd | Blackpool | 2017 |
| Ocial Commodity Trading Limited | London | 2013 |
| Ockendon Petrophysical Services Ltd | South Ockendon | 2010 |
| Octavia Energy Corporation Limited | London | 2022 |
| Oculus Global Limited | Grangemouth | 2017 |
| OD Contracts & Crushing Ltd | Dungannon | 2024 |
| ODE Asset Management Limited | Great Yarmouth | 2018 |