| Nutech Consultancy Ltd | Information & communication | 2025 |
| Nutmeg Group Limited | Professional & scientific | 2017 |
| Nutraflus Limited | Wholesale & retail | 2024 |
| Nutri Life Vending Ltd | Hospitality | 2019 |
| Nutribioticals Ltd | Wholesale & retail | 2012 |
| Nutrimends Ltd | Hospitality | 2025 |
| Nutriop Limited | Wholesale & retail | 2019 |
| Nutrisky Ltd | Wholesale & retail | 2023 |
| Nutristate Ltd | Manufacturing | 2025 |
| Nutrivolt Ltd | Wholesale & retail | 2018 |
| Nutrix Academia Ltd | Education | 2025 |
| Nuttall Caravan Site (Horton) Limited | Households | 1967 |
| Nutu Express Limited | Other services | 2019 |
| Nutu Transport Ltd | Transport & logistics | 2021 |
| Nuur Cosmetics Ltd | Wholesale & retail | 2022 |
| Nuvaixa Ltd | Wholesale & retail | 2025 |
| Nuvantahr Ltd | Administrative & support | 2021 |
| Nuvatra Technologies Limited | Professional & scientific | 2025 |
| Nuvessa Limited | Wholesale & retail | 2025 |
| Nuvolt Group Ltd | Financial services | 2023 |
| Nuvolt Ltd | Construction | 2021 |
| Nuvolt OMM Ltd | Households | 2023 |
| NV Cardiff Limited | Hospitality | 2022 |
| NV Products Limited | Information & communication | 2016 |
| NVA Construction Ltd | Manufacturing | 2018 |
| Nvite Group Limited | Information & communication | 2018 |
| NVK Facilities Group Ltd | Administrative & support | 2025 |
| Nvng Technology Limited | Other services | 2011 |
| NVT Properties Ltd | Real estate | 2021 |
| NW Consultancy Solutions Ltd | Professional & scientific | 2014 |
| NW Cosmetics Ltd | Wholesale & retail | 2018 |
| NWB11:11 Ltd | Administrative & support | 2024 |
| Nwdent Limited | Health & social care | 2026 |
| Nwhavna Mart Ltd | Wholesale & retail | 2025 |
| NWK Properties Ltd | Real estate | 2017 |
| NWL Contractors Ltd | Construction | 2025 |
| NWP Ecosse Limited | Real estate | 2025 |
| NWP Sameday Ltd | Transport & logistics | 2021 |
| NWR Ltd | Construction | 2015 |
| NWS Fabrications Ltd | Manufacturing | 2017 |
| Nwwc Training Ltd | Education | 2024 |
| NX Programming Ltd | Manufacturing | 2015 |
| NXT GEN Sports Ltd | Wholesale & retail | 2021 |
| NXT LVL Combat Academy Ltd | Arts & recreation | 2024 |
| Ny-Do Design Limited | Professional & scientific | 2010 |
| NYD Vegan Foods Ltd | Manufacturing | 2020 |
| Nyen Consulting Ltd | Professional & scientific | 2019 |
| Nyikai Property Ltd | Real estate | 2019 |
| NYK29 Logistics Limited | Transport & logistics | 2015 |
| Nyka Crafts Ltd | Wholesale & retail | 2026 |
| Nylander Couture Limited | Manufacturing | 2017 |
| Nynch Ltd | Information & communication | 2026 |
| NYO Metaverse Ltd | Information & communication | 2021 |
| Nyon Capital International Services Limited | Professional & scientific | 2025 |
| Nyon Capital Limited | Financial services | 2025 |
| Nyoni & SON Ltd | Health & social care | 2024 |
| Nysk Investments Ltd | Real estate | 2024 |
| Nysya Ltd | Transport & logistics | 2019 |
| Nytech Audio Ltd | Manufacturing | 2013 |
| Nyuzi Brands Limited | Wholesale & retail | 2020 |
| Nyuzi Limited | Wholesale & retail | 2020 |
| Nyuzione Limited | Other services | 2021 |
| Nyva Ltd | Wholesale & retail | 2026 |
| Nyxsolutions Ltd | Information & communication | 2025 |
| Nzuri Projects Limited | Professional & scientific | 2021 |
| N’Luxe Sparkle Service Ltd | Administrative & support | 2025 |
| O & H Services Limited | Wholesale & retail | 2007 |
| O a Mahmood Contracting Ltd | Professional & scientific | 2019 |
| O MI Learning Community Interest Company | Education | 2021 |
| O My COD 2018 Ltd | Hospitality | 2018 |
| O Pippin Decorators Limited | Construction | 2015 |
| O Squared Ltd | Real estate | 2024 |
| O&A Property Holdings Ltd | Real estate | 2024 |
| O&B Productions Ltd | Manufacturing | 2017 |
| O&G Safety Training (UK) Ltd | Energy | 2018 |
| O&P Constructions Ltd | Construction | 2015 |
| O' Donoghue Roofing and Property Maintainance Limited | Construction | 2010 |
| O'Brien & Partners KVE Ltd | Professional & scientific | 2018 |
| O'Brien Marketing Services Ltd | Professional & scientific | 2026 |
| O'Connell Bhatia Ltd | Wholesale & retail | 2019 |
| O'Connell Building Ltd | Construction | 2016 |
| O'Connor Transport Limited | Transport & logistics | 2004 |
| O'Ds Contract Services Ltd | Administrative & support | 2016 |
| O'Hara's Coffee House Limited | Hospitality | 2017 |
| O'Neill & Sons Building Services Ltd | Construction | 2015 |
| O'Neill Property Holdings Ltd | Real estate | 2023 |
| O'Regan Civils Ltd | Construction | 2021 |
| O-Moda Ltd | Wholesale & retail | 2017 |
| O-Motion Ltd | Administrative & support | 2021 |
| O-Stores Ltd | Wholesale & retail | 2020 |
| O. L. O. L. Ventures Limited | Administrative & support | 2016 |
| O. M. Charles Limited | Health & social care | 2018 |
| O.G Suppliers Ltd | Manufacturing | 2023 |
| O.J. Developments Limited | Construction | 1987 |
| O.R.G. Installations Ltd | Construction | 2018 |
| O.R.T. Services (UK) Limited | Construction | 2013 |
| O.S.D Group Limited | Real estate | 2018 |
| O.V. Bartlett & Sons (Cardiff) Limited | Construction | 1963 |
| O2S Group Ltd | Wholesale & retail | 2021 |
| O3 Financial Ltd | Information & communication | 2018 |