| Northern Mill Engine Society Limited (the) | Arts & recreation | 1973 |
| Northern Monkey Group Ltd | Hospitality | 2024 |
| Northern Oak Developments Limited | Real estate | 1999 |
| Northern Rockhopper Limited | Wholesale & retail | 2020 |
| Northern Trust Company Limited | Real estate | 1962 |
| Northern Trust Group 1 Limited | Professional & scientific | 2014 |
| Northern Trust Group 2 Limited | Professional & scientific | 2014 |
| Northern Trust Group Limited | Professional & scientific | 1993 |
| Northern Trust Land Limited | Real estate | 1987 |
| Northern Trust Properties Limited | Extraterritorial | 1985 |
| Northern V Properties Limited | Real estate | 2008 |
| Northern Victorian Pier Limited | Arts & recreation | 2011 |
| Northlands Property Lettings Ltd | Real estate | 2012 |
| Northmoor Trading Ltd | Wholesale & retail | 2026 |
| Northstar Creative Design Ltd | Professional & scientific | 2012 |
| Northwest Affordable Housing Limited | Construction | 2025 |
| Northwest Dairies Ltd | Wholesale & retail | 2012 |
| Northwest Delight Limited | Hospitality | 2025 |
| Northwest Developments Chorley Ltd | Administrative & support | 2018 |
| Northwest Drainage Supplies Limited | Wholesale & retail | 2025 |
| Northwest Driver Services Ltd | Transport & logistics | 2021 |
| Northwest Electrical and Property Services Ltd | Construction | 2021 |
| Northwest Firewood Supplies Ltd | Agriculture & fishing | 2026 |
| Northwest Hydraulic & Pneumatics Ltd | Manufacturing | 2018 |
| Northwest Network Services Limited | Information & communication | 2009 |
| Northwest Roofbox Hire Limited | Administrative & support | 2016 |
| Nouvo Recruitment Limited | Administrative & support | 2019 |
| Nova Building and Developments Ltd | Construction | 2019 |
| Nova Technical Services Ltd | Other services | 2022 |
| Novadawn Studios Ltd | Information & communication | 2019 |
| Novasoft Solutions Ltd | Information & communication | 2024 |
| Noventre UK Limited | Information & communication | 2025 |
| NOW Clare (Properties) Limited | Real estate | 2003 |
| Nowonco Limited | Wholesale & retail | 2025 |
| NR Local Retail Ltd | Wholesale & retail | 2025 |
| NRD Mailboxes Limited | Administrative & support | 2020 |
| NRD Media Limited | Information & communication | 2015 |
| NRI Security Ltd | Administrative & support | 2021 |
| NSB (NW) Limited | Other services | 2018 |
| NSB Installations Limited | Real estate | 2003 |
| NSB Property Holdings Limited | Administrative & support | 2012 |
| NSG Business Planning Limited | Administrative & support | 2009 |
| NSG Environmental Limited | Manufacturing | 1992 |
| NSJ Property Solutions Limited | Real estate | 2025 |
| NSP NSC Ltd | Real estate | 2023 |
| NT1 Construction Ltd | Construction | 2016 |
| NTC Medical Ltd | Other services | 2010 |
| NTI Construction Ltd | Construction | 2021 |
| NTN Properties (NW) Ltd | Real estate | 2024 |
| Ntsl Electrical Ltd | Construction | 2012 |
| Nubes Services Ltd | Professional & scientific | 2017 |
| Nuclear and Manufacturing Excellence Ltd | Professional & scientific | 2013 |
| Nugget Design Ltd. | Professional & scientific | 2012 |
| Nuhat Holdings Limited | Real estate | 2024 |
| Nuhat Projects Limited | Administrative & support | 2014 |
| Nuovo Sidcup Limited | Hospitality | 2021 |
| Nuthatch Estates Limited | Real estate | 2017 |
| Nutridive Ltd | Education | 2025 |
| Nuts About Health (Wigan) Ltd | Extraterritorial | 2024 |
| Nuts Bolts Limited | Professional & scientific | 2010 |
| NV Physiotherapy Limited | Health & social care | 2022 |
| NVQ Assessment Ltd | Education | 2025 |
| Nvunge Ltd | Education | 2026 |
| NW Concrete Services Limited | Construction | 2023 |
| NW Groundworks and Civils Limited | Construction | 2018 |
| NW Ultrasound Services Limited | Health & social care | 2012 |
| Nwems Ltd | Health & social care | 2025 |
| Nwfs Training Facilities Ltd | Construction | 2025 |
| Nysa International Ltd | Wholesale & retail | 2017 |
| O'Neill Primary Care Limited | Health & social care | 2024 |
| O'Neill Property Rental Limited | Real estate | 2026 |
| O.S PVT Ltd | Wholesale & retail | 2025 |
| Oak Car Sales Ltd | Wholesale & retail | 2013 |
| Oak Green Spice Ltd | Hospitality | 2023 |
| Oak Tree Tiles & Bathrooms Limited | Wholesale & retail | 2014 |
| Oak Vale (Whittle) Management Co Limited | Real estate | 2018 |
| Oakfield Fisheries Limited | Agriculture & fishing | 2025 |
| Oakfields Property Limited | Households | 2026 |
| Oakhouse Foods West Midlands Limited | Wholesale & retail | 2017 |
| Oakmill Care Ltd | Health & social care | 2018 |
| Oakridge Lettings Limited | Real estate | 2026 |
| OB Soundcrew Ltd | Information & communication | 2011 |
| OBS Medics Ltd | Health & social care | 2014 |
| Obvius Advantage Ltd | Extraterritorial | 2008 |
| OC Cleaning Solutions Limited | Administrative & support | 2011 |
| Ocean Capital Credit Ltd | Financial services | 2015 |
| Ochibo Spirit Limited | Professional & scientific | 2005 |
| OCM Properties Limited | Real estate | 2016 |
| Octv Limited | Information & communication | 2008 |
| Odaat Group Ltd | Construction | 2026 |
| Odie Transport Limited | Transport & logistics | 2015 |
| ODO Consultancy Ltd | Wholesale & retail | 2021 |
| Office Comfort Creations Limited | Wholesale & retail | 2025 |
| Office GEM Limited | Administrative & support | 2011 |
| Office Heaven Limited | Wholesale & retail | 2008 |
| Offshore Maritime Services Limited | Transport & logistics | 2018 |
| Offshore Wind Solutions Ltd | Manufacturing | 2026 |
| Offsite Design Solutions Ltd | Professional & scientific | 2011 |
| Ogea Properties Limited | Real estate | 2024 |
| OJ Building Solutions Limited | Construction | 2025 |