| Nalits Ltd | Information & communication | 2006 |
| Nana VFX Ltd | Information & communication | 2016 |
| Nano Infrastructure Advisors Ltd | Professional & scientific | 2023 |
| Narnia Land Limited | Real estate | 2025 |
| Naru Consultancy Limited | Professional & scientific | 2024 |
| Nasir Enterprise Ltd | Wholesale & retail | 2023 |
| Nassington Consultancy Services Ltd | Professional & scientific | 2017 |
| National Accident Repair Ltd | Wholesale & retail | 2023 |
| Natural Windows Limited | Construction | 2009 |
| NB Capital Property Limited | Real estate | 2026 |
| NCP Plumbing & Heating Ltd | Construction | 2019 |
| NE Healthcare Ltd | Health & social care | 2014 |
| Neat CUT Limited | Construction | 2004 |
| Nelson Jane Recruitment Limited | Administrative & support | 2007 |
| Nereus Services LLP | | 2021 |
| Network Data Ltd | Information & communication | 2024 |
| Network DRY Cleaners Limited | Other services | 2021 |
| Neuroimaging Solutions Ltd | Health & social care | 2023 |
| Neuron Consulting Ltd | Professional & scientific | 2017 |
| Neurorad Limited | Health & social care | 2014 |
| Neuroscan Ltd | Health & social care | 2012 |
| Never Alone Studio Ltd | Information & communication | 2023 |
| New Foundations Propco Ltd | Real estate | 2024 |
| New Leaf Search Limited | Administrative & support | 2004 |
| Nexora Consulting Ltd | Professional & scientific | 2024 |
| Nextbid Limited | Real estate | 2009 |
| Nextcase Limited | Real estate | 2006 |
| NFP Street Limited | Professional & scientific | 2022 |
| Nhac Limited | Construction | 2018 |
| Nick Bodyworks Limited | Wholesale & retail | 2015 |
| Nick Perfect Cleaner Ltd | Administrative & support | 2021 |
| Nigel Edwards Consulting Ltd | Professional & scientific | 2026 |
| Nigerian Schools Foundation (UK) | Education | 2018 |
| Night & Day London Ltd | Arts & recreation | 2015 |
| Niikins Services Ltd | Other services | 2026 |
| Niko Investments Limited | Real estate | 2023 |
| Nikolaos Fotiadis Limited | Health & social care | 2013 |
| Nila Technology Limited | Information & communication | 2019 |
| Niratha Technologies Ltd. | Information & communication | 2013 |
| NJM HR and Compliance Ltd | Administrative & support | 2025 |
| NK Power & Engineering Ltd | Construction | 2026 |
| NLG Flooring Ltd | Construction | 2026 |
| NLP Project Services Limited | Professional & scientific | 2017 |
| Nmaj Holdings Limited | Households | 2022 |
| NN Medical Limited | Health & social care | 2025 |
| Noir Drive Ltd | Transport & logistics | 2025 |
| Nooch Creative Ltd | Information & communication | 2022 |
| Noosa International Ltd | Wholesale & retail | 2008 |
| Noosa Investments Limited | Real estate | 2016 |
| North Green Trans Ltd | Transport & logistics | 2019 |
| Northgate Traders (City) Limited | Extraterritorial | 1940 |
| Northwest London Maintenance Limited | Real estate | 2023 |
| Northwood Restaurant Limited | Hospitality | 2023 |
| Notiotech Limited | Administrative & support | 2017 |
| Novahealth Limited | Wholesale & retail | 2004 |
| NOW Gyms Limited | Arts & recreation | 2006 |
| Npro Construction Ltd | Construction | 2024 |
| Nrky Ltd | Wholesale & retail | 2026 |
| NSA Real Estates Ltd | Real estate | 2021 |
| NSN Traders Limited | Wholesale & retail | 2017 |
| NSV Solutions Limited | Construction | 2016 |
| Ntrh Ltd | Construction | 2025 |
| Nyarko Holdings Limited | Administrative & support | 2019 |
| O KAY Development Ltd | Construction | 2026 |
| O.T.Client Services Limited | Information & communication | 2017 |
| Oak Homecare Ltd | Health & social care | 2022 |
| Oakgrane Ltd | Construction | 2010 |
| Oakhurst Capital Ltd | Real estate | 2023 |
| Oakwood (HC) Limited | Financial services | 2019 |
| Oakwood (Insurances) Limited | Financial services | 1965 |
| Oakwood Premium Finance Limited | Financial services | 2012 |
| OC Property Holdings Ltd | Real estate | 2024 |
| Odontic Ltd | Health & social care | 2022 |
| Odysseus and Penelope Investing Ltd | Construction | 2022 |
| Oflynnservices Ltd | Information & communication | 2024 |
| OGC Contracts Ltd | Construction | 2019 |
| Olley Beauty Limited | Wholesale & retail | 2019 |
| OM Heating and Plumbing Ltd | Construction | 2018 |
| OM Nithansi Limited | Health & social care | 2019 |
| OM SAI Skandha Investment Ltd | Real estate | 2022 |
| Omega Chauffeurdrive Limited | Transport & logistics | 2018 |
| Omni Health and Fitness Ltd | Arts & recreation | 1998 |
| ON Screen JM London Ltd. | Arts & recreation | 2015 |
| ON SET Scenery Ltd | Construction | 2025 |
| One Dental Holdings Ltd | Health & social care | 2021 |
| One Integrated Management Ltd | Construction | 2024 |
| Onestop IPC Ltd | Professional & scientific | 2024 |
| ONETECH365 Ltd | Information & communication | 2022 |
| OOB Latinoamericana Ltd | Wholesale & retail | 2018 |
| Open Mind Building Services Ltd | Administrative & support | 2014 |
| Opulent Seven Ltd | Administrative & support | 2022 |
| Orange Circle Investments Limited | Real estate | 2017 |
| Orbis Lata Capital UK Ltd | Other services | 2024 |
| Orbiter Limited | Wholesale & retail | 2006 |
| Orca Financial Planning Ltd | Extraterritorial | 2012 |
| Ordenado Ltd | Construction | 2023 |
| Orex Consultancy Limited | Information & communication | 2014 |
| Orinoco Associates Ltd | Professional & scientific | 2025 |
| Orirose Ltd | Real estate | 2025 |
| Orixa Transport Ltd | Transport & logistics | 2026 |