| North Greetwell Developments Limited | Construction | 2024 |
| North Kesteven Academy | Education | 2011 |
| North Lincs Construction Ltd | Construction | 2025 |
| North Parade Management Services Ltd | Real estate | 2024 |
| North Scarle Property Ltd | Real estate | 2019 |
| North Warren Road Properties Limited | Households | 1995 |
| North West London Rheumatology Limited | Health & social care | 2017 |
| Northgate Court (Louth) Management Company Limited | Households | 1996 |
| Northgate Newark Limited | Construction | 2013 |
| Northseek HDD Services Ltd | Construction | 2025 |
| Northwick (South) Limited | Construction | 2025 |
| Northwick Group Ltd | Financial services | 2023 |
| Northwick Horizon Ltd | Wholesale & retail | 2026 |
| Northwick Limited | Construction | 2013 |
| Northwood (Lincs) Ltd | Real estate | 2012 |
| Northwood Banks & Co Limited | Professional & scientific | 2005 |
| Norwich Hand Clinic Ltd | Health & social care | 2026 |
| Norwich Hand Surgery Ltd | Health & social care | 2017 |
| Nostalgia Games Ltd | Wholesale & retail | 2022 |
| Nostalgia Resurrected Limited | Construction | 2024 |
| Nostos Consulting Ltd | Professional & scientific | 2019 |
| NOT Dead Tech Ltd | Administrative & support | 2017 |
| NOT That Kind of Community Interest Company | Health & social care | 2023 |
| Nottingham Oncology Services LLP | | 2014 |
| Nottingham Property Company Limited | Real estate | 2018 |
| Nottingham ST Anns Limited | Construction | 2013 |
| Nottingham Tamil Sports Club Ltd | Arts & recreation | 2025 |
| Nottingham Urology LLP | | 2019 |
| Nottingham Writers' Studio C.I.C. | Arts & recreation | 2008 |
| Nova Homes Ltd | Real estate | 2021 |
| Nova Talent Ltd | Administrative & support | 2022 |
| Novacenter Ltd | Wholesale & retail | 2024 |
| Novaminis Ltd | Extraterritorial | 2015 |
| Novello Care Ltd | Health & social care | 2023 |
| Novelty Event Vehicles Ltd | Other services | 2020 |
| Novix Ltd | Wholesale & retail | 2023 |
| Novobooks Limited | Information & communication | 2023 |
| Novus Power Holdings Limited | Financial services | 2025 |
| Nowack Transportation Limited | Transport & logistics | 2023 |
| NOX Labs Limited | Wholesale & retail | 2025 |
| Noxen Clothing Ltd | Wholesale & retail | 2025 |
| NPK Limited | Wholesale & retail | 2025 |
| NR Brickwork Ltd | Construction | 2024 |
| NR Health Ltd | Health & social care | 2025 |
| Nsdq Legal Limited | Professional & scientific | 2026 |
| NSH Partners Ltd | Health & social care | 2025 |
| Nude Food Events Ltd | Hospitality | 2025 |
| Number One Hair and Beauty Limited | Other services | 2011 |
| Nurtra Ltd | Information & communication | 2026 |
| Nutkins Property Limited | Real estate | 2022 |
| Nutrapharma Limited | Professional & scientific | 2014 |
| Nutritional Planning Ltd | Administrative & support | 2017 |
| NV8 Projects Limited | Construction | 2013 |
| Nvelope Recruitment Ltd | Administrative & support | 2023 |
| NW (Lincs) Holdings Ltd | Real estate | 2025 |
| NW Counselling Hub CIC | Health & social care | 2017 |
| NW Countryside Services Ltd | Agriculture & fishing | 2020 |
| Nwortho Ltd | Health & social care | 2019 |
| Nyathi Properties Ltd | Extraterritorial | 2015 |
| O Clarke Designs Ltd | Professional & scientific | 2021 |
| O Rourke Bespoke Joinery Ltd | Construction | 2013 |
| O&O Cleaning Solutions Ltd | Administrative & support | 2025 |
| O'Boyle Brothers Limited | Construction | 2009 |
| O'Connells Transport Ltd | Transport & logistics | 2024 |
| O'Marley Roofing Contractors Ltd | Construction | 2026 |
| O'Meara Holdings Ltd | Financial services | 2024 |
| O'Rourke Property Ltd | Real estate | 2024 |
| O-Cube Limited | Health & social care | 2022 |
| O-Perspective Ltd | Professional & scientific | 2020 |
| OA Property Management Ltd | Real estate | 2024 |
| Oak Chimney Services Ltd | Administrative & support | 2021 |
| Oak Farm Geotechnical Services Ltd. | Construction | 2014 |
| Oak Farm Properties Limited | Real estate | 2017 |
| Oak View (Lincoln) Management Company Limited | Real estate | 2008 |
| Oakbar Ltd | Manufacturing | 2024 |
| Oakdene Developments (Lincs) Limited | Construction | 2016 |
| Oakeaston Holdings Limited | Financial services | 2023 |
| Oakheart Joinery Ltd | Construction | 2018 |
| Oakhill Leisure Ltd | Hospitality | 2015 |
| Oakhouse Architecture Limited | Professional & scientific | 2020 |
| Oakley & Hudson Ltd. | Hospitality | 2018 |
| Oakley Medical Limited | Health & social care | 2016 |
| Oakmoor Interiors Ltd | Wholesale & retail | 2024 |
| Oakridge (GF) Ltd | Construction | 2026 |
| Oakridge (TW) Ltd | Construction | 2026 |
| Oakridge (WR) Ltd | Construction | 2025 |
| Oakstone Realty Ltd | Real estate | 2026 |
| Oakwell Homes Limited | Real estate | 2003 |
| Oakwood Building Consultancy Services Limited | Professional & scientific | 2015 |
| Oakwood Contracting Services Limited | Construction | 2016 |
| Oakwood Residential Developments Limited | Construction | 2014 |
| Oasis (Lincoln) Ltd | Arts & recreation | 2009 |
| Oatz & Stokes Limited | Hospitality | 2025 |
| OB Brothers Holdings Limited | Financial services | 2023 |
| OB Plumbing & Heating Limited | Construction | 2021 |
| Obam Domestic Lifts Services Limited | Other services | 2000 |
| Obam Holdings Limited | Financial services | 2023 |
| Obholzer ENT Skull Base Ltd | Health & social care | 2016 |
| Object & Line Ltd | Wholesale & retail | 2009 |
| Obsession Engineering Ltd | Wholesale & retail | 2011 |