| Nova Petfoods Limited | Wholesale & retail | 2024 |
| Nova Properties Group Ltd | Real estate | 2021 |
| Nova Safety Ltd | Professional & scientific | 2024 |
| Nova Skin Clinic Limited | Other services | 2022 |
| Nova Smiles Centre Limited | Health & social care | 2025 |
| Novafronts Ltd | Manufacturing | 2025 |
| Novakeys Home Stays Limited | Real estate | 2026 |
| Novel Business Management Solutions Ltd | Administrative & support | 2017 |
| Novexis Logistics Ltd | Transport & logistics | 2026 |
| Novo Music Limited | Arts & recreation | 2025 |
| Novoget Limited | Construction | 2023 |
| NOW International Limited | Wholesale & retail | 2019 |
| Nowak Logistics Ltd | Transport & logistics | 2026 |
| NP Key Services Limited | Real estate | 2020 |
| NR Sons Group Ltd | Transport & logistics | 2026 |
| NRU FM Services Ltd | Administrative & support | 2023 |
| NRY Ltd | Information & communication | 2024 |
| NS Enterprises Limited | Transport & logistics | 2010 |
| NS Global Limited | Information & communication | 2010 |
| NSB Partners Ltd | Real estate | 2022 |
| NSD Wholesale Ltd | Wholesale & retail | 2024 |
| NSG Property Investment Ltd | Real estate | 2022 |
| Nsir Ltd | Wholesale & retail | 2024 |
| NST Builders Ltd | Construction | 2026 |
| NST Foods UK Ltd | Hospitality | 2021 |
| NT Homes Limited | Real estate | 2024 |
| NT Khehra Limited | Real estate | 2024 |
| NT Security Ltd | Administrative & support | 2026 |
| NTF International Ltd | Manufacturing | 2022 |
| NTR Biosensors Limited | Manufacturing | 2025 |
| NU Real Estate Ltd | Real estate | 2022 |
| Nucura Ltd | Health & social care | 2025 |
| Numnore Limited | Information & communication | 2018 |
| Numus Ltd | Information & communication | 2025 |
| NUR49 Ltd | Hospitality | 2026 |
| Nurture Pathways Limited | Health & social care | 2022 |
| Nush Medical Services Ltd | Health & social care | 2025 |
| Nush Properties Ltd | Households | 2018 |
| Nusumu IT Solutions Ltd | Information & communication | 2018 |
| Nuvana Services Ltd | Other services | 2025 |
| NV Strong Ltd | Construction | 2025 |
| NVN3 Ltd | Construction | 2022 |
| NW Building London Ltd | Construction | 2014 |
| NW Home Exteriors Ltd | Construction | 2025 |
| NW10 Music Ltd | Information & communication | 2013 |
| Nwsb Trading Limited | Construction | 2025 |
| Nxkerr Limited | Health & social care | 2021 |
| Nyabo's Ltd | Wholesale & retail | 2025 |
| Nyle Ventures Ltd | Professional & scientific | 2026 |
| Nynindustries Ltd | Wholesale & retail | 2025 |
| Nysdill Group Limited | Hospitality | 2020 |
| Nysdill Hotel Heathrow Ltd | Hospitality | 2025 |
| Nysdill Hotel Management Ltd | Hospitality | 2022 |
| Nysdill Hotel Norwich Ltd | Hospitality | 2024 |
| Nyse Ventures Ltd | Wholesale & retail | 2020 |
| Nūma&Co Limited | Health & social care | 2025 |
| O & S Assets Ltd | Real estate | 2021 |
| O Beirut Limited | Construction | 2020 |
| O&S Airspace Limited | Real estate | 2021 |
| O'Natural Ltd | Manufacturing | 2020 |
| O'Sullivan Building Performance Limited | Construction | 2026 |
| O-K-Sta Ltd | Wholesale & retail | 2025 |
| O2 Scaffolding Limited | Construction | 2024 |
| Oak Heights Group Ltd | Financial services | 2025 |
| Oak Heights Management Limited | Real estate | 2025 |
| Oakley Towers Ltd | Real estate | 2022 |
| Oakmere Retail Ltd | Wholesale & retail | 2025 |
| Oakmont Realty Ltd | Real estate | 2025 |
| Oakmonts Ventures Ltd | Information & communication | 2025 |
| Oaknova Ltd | Construction | 2026 |
| Oaksmont Ventures Ltd | Professional & scientific | 2025 |
| Oasco Limited | Wholesale & retail | 2023 |
| Oasis Consultants and ERP Solutions Limited | Construction | 2009 |
| Obelix Training Limited | Professional & scientific | 1997 |
| OBS Fruit and Vegetables Limited | Wholesale & retail | 2025 |
| Obsess Boutique Ltd | Manufacturing | 2015 |
| Occassionz Ltd | Administrative & support | 2020 |
| Ocdiala Ltd | Professional & scientific | 2013 |
| Ocean Across Ltd | Transport & logistics | 2025 |
| Ocean Childcare and Nanny Ltd | Education | 2015 |
| Ocean First Cargo Limited | Transport & logistics | 2020 |
| Ocean Horizon London Limited | Administrative & support | 2022 |
| Ocean Horizon Shipping Limited | Administrative & support | 2009 |
| Ocean Transport & Shipping (UK) Ltd | Administrative & support | 2014 |
| OCG Assessing Limited | Education | 2010 |
| Octopus Property Maintenance Ltd | Households | 2022 |
| Odai Takeaway Ltd | Hospitality | 2026 |
| Oddball Motion Pictures (UK) Limited | Information & communication | 2021 |
| Odoreme Ltd | Wholesale & retail | 2025 |
| Officely Limited | Administrative & support | 2024 |
| OH Crumbs London Limited | Hospitality | 2026 |
| OH the Thinks YOU CAN Think! Limited | Professional & scientific | 2019 |
| OHA Investment Ltd | Real estate | 2021 |
| Oksi Ltd | Wholesale & retail | 2019 |
| Olaru Art Ltd | Transport & logistics | 2025 |
| Old Lady Ventures Ltd | Transport & logistics | 2023 |
| Old Oscott Essentials Limited | Wholesale & retail | 2023 |
| Old Park Mews (West) Management Company Limited | Households | 1981 |
| Old Park Mews Management Co. Ltd. | Households | 2004 |
| Old Town Design Ltd | Construction | 2012 |