| NSC Land and Property Consultants Limited | Professional & scientific | 2012 |
| NSI Solutions Ltd | Information & communication | 2023 |
| Nsum Ltd | Health & social care | 2019 |
| NSW Civil Engineering Ltd | Construction | 2008 |
| NT Service Designs Limited | Information & communication | 2024 |
| NT Subsea Engineering Limited | Administrative & support | 2024 |
| NTB Engineering Services Ltd | Professional & scientific | 2023 |
| Ntegral Limited | Information & communication | 2020 |
| Ntsw Property Ltd | Real estate | 2019 |
| NTT Telecoms Limited | Information & communication | 2018 |
| NU Bros Ltd | Information & communication | 2024 |
| NU Build Consulting Limited | Professional & scientific | 2023 |
| NU Concepts Limited | Professional & scientific | 2011 |
| NU Life Consulting Ltd | Professional & scientific | 2023 |
| Nubiggs Limited | Information & communication | 2015 |
| Nuclear Associates Ltd. | Administrative & support | 2007 |
| Nuclear Restoration Services Limited | Other services | 1988 |
| Nuclear Risk Management Limited | Professional & scientific | 2015 |
| Nuclear Ventilation Services Limited | Professional & scientific | 2021 |
| Nudle Media Ltd | Information & communication | 2026 |
| Nuera Limited | Construction | 2017 |
| Nugenx Limited | Wholesale & retail | 2019 |
| Nugeri Engineering Ltd | Professional & scientific | 2021 |
| Nugget Marketing Ltd | Professional & scientific | 2021 |
| Nuhawi Limited | Real estate | 2013 |
| Nuko Planning Ltd | Professional & scientific | 2020 |
| Number 9 Cafe Limited | Hospitality | 2024 |
| Number 9 Events Limited | Hospitality | 2026 |
| Numbersixtyeight Limited | Professional & scientific | 2023 |
| Nummi Design LAB Limited | Wholesale & retail | 2026 |
| Nurture by Natalie Ltd | Education | 2024 |
| Nurture in Care Ltd | Health & social care | 2025 |
| Nurturenest Family Care and Coaching Ltd | Administrative & support | 2024 |
| Nurturepro Healthcare Limited | Health & social care | 2025 |
| Nuso Limited | Wholesale & retail | 2019 |
| Nut-Locker Services Limited | Construction | 2013 |
| Nutri Kitchen Ltd | Hospitality | 2022 |
| Nutriwise Education Ltd | Professional & scientific | 2025 |
| Nutty Boltfesssor Ltd | Wholesale & retail | 2024 |
| Nutty Racing Ltd | Professional & scientific | 2025 |
| Nuvi HR Limited | Administrative & support | 2025 |
| Nuvia Limited | Water & waste | 1986 |
| Nuvia Pensions Limited | Financial services | 2021 |
| Nuvu Development Limited | Construction | 2018 |
| Nuvu Living (Wavertree) LLP | | 2018 |
| Nuvu Living LLP | | 2018 |
| NV Cloud Solutions Limited | Information & communication | 2023 |
| NV Consultancy Limited | Administrative & support | 2016 |
| NVB Wrexham Ltd | Wholesale & retail | 2015 |
| NW Boilers Ltd | Construction | 2020 |
| NW E Bikes Limited | Wholesale & retail | 2025 |
| NW Firecontrol Limited | Public administration | 2007 |
| NW Piping Design Limited | Professional & scientific | 2017 |
| Nwabudike Ltd | Health & social care | 2024 |
| Nwardyfitness Ltd | Information & communication | 2025 |
| Nwdf Ltd | Transport & logistics | 2013 |
| NWF (Energy & Environmental Technologies) LP | | 2010 |
| Nwfc Limited | Arts & recreation | 2024 |
| NWP Whitby Ltd | Hospitality | 2025 |
| NX Property Limited | Real estate | 2023 |
| Nxgen Lifting Ltd | Construction | 2021 |
| Nyembua Financial Ltd | Financial services | 2022 |
| Nykan Aerotech Limited | Professional & scientific | 2018 |
| Nyland Construction Limited | Construction | 2015 |
| Nylese Limited | Administrative & support | 2016 |
| Nyree Ellison Anjos Consultants Limited | Administrative & support | 2014 |
| Nyved Clinical Services Ltd | Administrative & support | 2025 |
| N’Genius Technology Limited | Extraterritorial | 1993 |
| O&M Medical Service Limited | Health & social care | 2014 |
| O'BRIEN88 Business Services Limited | Public administration | 2018 |
| O'Connor Consulting Ltd | Professional & scientific | 2025 |
| O'Connor Project Management Limited | Other services | 2017 |
| O'Hara Building Services Ltd | Construction | 2023 |
| O'Hare Stress Consultancy Limited | Professional & scientific | 2016 |
| O'Laribo Business Solutions Ltd | Wholesale & retail | 2017 |
| O'Malleys Gym Limited | Arts & recreation | 2024 |
| O.B.Y.Limited | Construction | 1967 |
| O.W.Fast Engineering Ltd | Professional & scientific | 2016 |
| Oak Psychological Services Ltd | Health & social care | 2025 |
| Oaka Medserve Ltd | Professional & scientific | 2018 |
| Oakburn Developments Limited | Real estate | 2015 |
| Oakland Consultancy Ltd | Professional & scientific | 2025 |
| Oaklands Safety Consulting Limited | Administrative & support | 2016 |
| Oakleaf Developments (NW) Limited | Construction | 2018 |
| Oakmead Building Services Limited | Construction | 2014 |
| Oaktrack Ltd | | 1999 |
| Oaktree Engineering Services Ltd | Professional & scientific | 2022 |
| Oakwell Digital Ltd | Wholesale & retail | 2022 |
| Oakwood Elite Cleaning Services Ltd | Administrative & support | 2024 |
| Oakwood Upholstery Limited | Manufacturing | 1990 |
| Oana Andrei Ltd | Professional & scientific | 2018 |
| Oasis Tanning Rooms Limited | Arts & recreation | 2016 |
| Oates Estates Ltd | Real estate | 2023 |
| Oates Recovery Ltd. | Transport & logistics | 2017 |
| OB Futures Ltd | Professional & scientific | 2019 |
| OB IT Tech Services Limited | Information & communication | 2024 |
| Obcelca Limited | Information & communication | 2017 |
| OBD Electrical Ltd | Construction | 2016 |
| OBD Instrumentation Ltd | Professional & scientific | 2020 |
| Objective Decisions Ltd | Information & communication | 2015 |