| Nani's Pizza Ltd | Hospitality | 2025 |
| Nasfa UK Limited | Real estate | 2022 |
| Nattsvart Records Ltd | Information & communication | 2023 |
| Natural Poem Studio Ltd | Manufacturing | 2024 |
| Nauvoo Ventures Limited | Professional & scientific | 2016 |
| NB Food Services Ltd Ltd | Extraterritorial | 2021 |
| NBS Construction Limited | Construction | 2020 |
| Neel 1 UK Ltd | Wholesale & retail | 2026 |
| Neuro Align Ltd | Health & social care | 2021 |
| Neuromod Ltd | Extraterritorial | 2024 |
| New Broad Street Motors Ltd | Wholesale & retail | 2003 |
| New Garden Barry 118 Limited | Hospitality | 2019 |
| New LED Light Limited | Manufacturing | 2008 |
| New Yang's Limited | Hospitality | 2017 |
| Newbaron Accountancy Services Limited | Professional & scientific | 2006 |
| Newell Human Factors Ltd | Professional & scientific | 2020 |
| Nexus Lasers & Robotics Ltd | Manufacturing | 2024 |
| Nexus Protection Service UK Ltd | Administrative & support | 2025 |
| NIA Eira Healthcare Limited | Health & social care | 2016 |
| Nichola Jones Associates Ltd | Professional & scientific | 2022 |
| Nicums NUM Nums CYF | Manufacturing | 2021 |
| Nigel Hughes CYF | Information & communication | 2022 |
| Nigel Morgan Rail Ltd | Construction | 2017 |
| Nima-Q CYF | Wholesale & retail | 2025 |
| Nisray Limited | Administrative & support | 2023 |
| Niveza Ltd | Real estate | 2018 |
| Njspackman Ltd. | Information & communication | 2016 |
| NLE Financial Contractors Ltd | Financial services | 2015 |
| NM66 Limited | Real estate | 2026 |
| Nobeear Limited | Real estate | 2000 |
| Noblecourt Limited | Health & social care | 2009 |
| Nobody Here Film Ltd | Information & communication | 2020 |
| Nomah Dance Ltd | Arts & recreation | 2026 |
| Northberry Limited | Health & social care | 2009 |
| Northcote Developments Limited | Hospitality | 1964 |
| NOS DA Ltd | Real estate | 2019 |
| Nostravia Ltd | Professional & scientific | 2025 |
| Noyztoyz.Com Limited | Information & communication | 2000 |
| NRC Multifinish Ltd | Construction | 2022 |
| Numi Skin Limited | Other services | 2021 |
| Nuvramoe Ltd | Hospitality | 2025 |
| NV Associates Limited | Professional & scientific | 2019 |
| NV Property Investments Limited | Real estate | 2017 |
| NW Environmental Limited | Information & communication | 2015 |
| O S Asset Management Ltd | Financial services | 2018 |
| O'Neill Associates (Search & Selection) Limited | Administrative & support | 2002 |
| O'Shea's Fish and Chip Cafe Limited | Hospitality | 2013 |
| O.K. Scaffolding Limited | Construction | 1982 |
| Oakwater Luxury Lifestyle Living (Elysium) Ltd | Construction | 2023 |
| Oakwater Luxury Lifestyle Living Ltd | Construction | 2018 |
| Ocean Sky Wellness Limited | Other services | 2025 |
| Ockwell Properties Limited | Wholesale & retail | 2024 |
| OGE Properties Limited | Wholesale & retail | 2021 |
| OK Estates Ltd | Real estate | 2015 |
| Okosisi Limited | Health & social care | 2022 |
| OLI Spencer Aesthetics Ltd | Health & social care | 2018 |
| Olivia MAE Grill & Treats Ltd | Hospitality | 2026 |
| Olympus Flooring Contractors Ltd | Construction | 2023 |
| Olynpaidd M&E 2008 Ltd | Construction | 2010 |
| Onboard Logistics Ltd | Transport & logistics | 2025 |
| One Family NO Division CIC | Wholesale & retail | 2026 |
| One Sport Technologies Ltd | Wholesale & retail | 2026 |
| One Stop Garage Barry Limited | Wholesale & retail | 2018 |
| One UP Golf Ltd | Wholesale & retail | 2024 |
| Oneeighty Online Coaching Ltd | Other services | 2025 |
| Online Hearing Aids Fit Limited | Wholesale & retail | 2023 |
| OP Clutterbuck Limited | Financial services | 2024 |
| Optimise Technology Solutions Ltd | Information & communication | 2022 |
| OPTIMUM23 Ltd. | Health & social care | 2024 |
| Orbits IT (South West) Limited | Information & communication | 2020 |
| Orhan Grill & Dessert Ltd | Hospitality | 2024 |
| Original Business IT Solutions Limited | Information & communication | 2009 |
| Orvixo Ltd | Information & communication | 2026 |
| Oshi's World | Education | 2016 |
| Osmo Electrical Limited | Construction | 2026 |
| Otterbourne Orthopaedics Limited | Health & social care | 2016 |
| OUTCOME1 Ltd | Education | 2020 |
| Overtheres Stories CIC | Arts & recreation | 2025 |
| O’Reilly Precast Limited | Manufacturing | 2017 |
| P & CM Construction Consultancy Limited | Professional & scientific | 2013 |
| P Beard Properties Limited | Real estate | 2009 |
| P Douglas Construction Ltd Ltd | Construction | 2024 |
| P Eveleigh Waste Management Limited | Water & waste | 2026 |
| P G Kemp Property Ltd | Real estate | 2024 |
| P H Cooling Ltd | Construction | 2014 |
| P M Contract (Services) Limited | Administrative & support | 2013 |
| P S Instalations Limited | Construction | 2011 |
| P&A Property Solution Ltd | Real estate | 2025 |
| P.E. Bullen (Sheetmetal) Limited | | 1988 |
| P.W. Millar Holdings Limited | Financial services | 2025 |
| Pace-Setters Group Limited | Wholesale & retail | 2025 |
| Pacfrey Properties Limited | Real estate | 2026 |
| Paletta Pizzeria Limited | Hospitality | 2018 |
| Pamwechete Limited | Professional & scientific | 2025 |
| Parca Properties Ltd | Real estate | 2020 |
| Parcel Perfect Ltd | Transport & logistics | 2021 |
| Park Consultants Ltd | Hospitality | 2025 |
| Park Estates & Lettings Ltd | Real estate | 2017 |
| Parkrow Care Limited | Health & social care | 2003 |
| Parsonage Farm Racing Limited | Arts & recreation | 1991 |