| Ncfed Training LP | | 2021 |
| ND Mediation and People Ltd | Administrative & support | 2020 |
| Neda Solutions Limited | Administrative & support | 2019 |
| Nefaceaesthetics Ltd | Other services | 2025 |
| Neil Minter & Associates Limited | Health & social care | 2010 |
| Nelsun Teck Ltd | Administrative & support | 2022 |
| Neon Pharma Ltd | Health & social care | 2010 |
| Neonurture Physiotherapy Ltd | Health & social care | 2025 |
| Neruda Limited | Financial services | 2012 |
| Neuro Logic Health Ltd | Health & social care | 2025 |
| Neurocharge Medical Devices Limited | Manufacturing | 2024 |
| New Clear Visuals Ltd | Information & communication | 2012 |
| New Globe Homes Limited | Construction | 2015 |
| New North Limited | Professional & scientific | 2025 |
| New Road Esher Ltd | Households | 2018 |
| New York Habitat London Limited | Real estate | 2002 |
| Nick Beardshaw Consultancy Ltd | Professional & scientific | 2025 |
| Nick Stafford Pubs Ltd | Hospitality | 2025 |
| Nightingales Property Ltd. | Real estate | 2015 |
| Nitska Limited | Wholesale & retail | 2024 |
| NJ Growth Ltd | Financial services | 2024 |
| NJ Media Ltd | Wholesale & retail | 2024 |
| NO. 1 ST. Andrew's Road Management Company Limited | Households | 1995 |
| NO.4 Boutique Limited | Wholesale & retail | 2024 |
| Noblecrest Care Limited | Health & social care | 2025 |
| Nomad Neuroscience Ltd | Professional & scientific | 2025 |
| Noontime Limited | Wholesale & retail | 2026 |
| Northumberland House Limited | Hospitality | 2004 |
| Norwood Consulting Services Limited | Professional & scientific | 2018 |
| Novaway Limited | Wholesale & retail | 2026 |
| Novitas Capital Advisors Limited | Financial services | 2019 |
| NOW Services Ltd | Financial services | 2008 |
| Number 34 Entertainment Ltd | Information & communication | 2022 |
| Nurse Georgie Limited | Health & social care | 2025 |
| Nutmeg Consulting Limited | Real estate | 2017 |
| NVM Ltd | Information & communication | 2026 |
| NW Anaesthetics Ltd | Health & social care | 2021 |
| Nyewood One Limited | Professional & scientific | 2020 |
| O H Associates Limited | Professional & scientific | 2003 |
| Oakhill (Surbiton) Residents Association Limited | Other services | 1962 |
| Oakwood Kuoni House Developments Limited | Construction | 2019 |
| Oakwood Real Estate Limited | Other services | 2012 |
| Obanmar Consulting Limited | Information & communication | 2023 |
| Objectiviti Ltd | Professional & scientific | 2022 |
| Octopoda Research Ltd | Financial services | 2021 |
| Octowork Renovations Limited | Construction | 2025 |
| OEM Support Solutions Ltd | Professional & scientific | 2021 |
| OGL Properties Ltd | Real estate | 2015 |
| OHM Media Ltd | Professional & scientific | 2025 |
| Ojas Origins Ltd | Administrative & support | 2022 |
| Oldthorpe Residents Association Limited | Households | 1994 |
| Ombu & Cedar Ltd | Wholesale & retail | 2025 |
| ON the Rocks Mixology Ltd | Hospitality | 2025 |
| ON Your Business Limited | Professional & scientific | 2016 |
| One Down Four UP Ltd | Professional & scientific | 2024 |
| One Milton Road Limited | Households | 2007 |
| One Solution Construction Ltd | Construction | 2012 |
| Ontology Limited | Professional & scientific | 2020 |
| Ontrack Remove and Services Limited | Construction | 2018 |
| Oodles Trading Limited | Wholesale & retail | 2000 |
| Open Spaces Limited | Administrative & support | 1997 |
| Optic Interiors Limited | Professional & scientific | 1999 |
| Optical Character Recognition | | 1997 |
| Optimal Mechanics Solutions Ltd | Construction | 2025 |
| Optisale Limited | Real estate | 2018 |
| Optym Consulting Ltd | Professional & scientific | 2023 |
| Oracle Finance Limited | Professional & scientific | 2003 |
| Orange Financial Limited | Real estate | 2015 |
| Orange Zest Ltd | Health & social care | 2022 |
| Orchard Way Residents Limited | Other services | 1981 |
| ORE Investments Limited | Real estate | 2019 |
| Organised Chaos London Limited | Arts & recreation | 2021 |
| Oriental Business Link Ltd. | Administrative & support | 2016 |
| Oriental Carpet Warehouse Limited(The) | Wholesale & retail | 1987 |
| Origins Design Limited | Manufacturing | 2011 |
| Orthofuse Ltd | Professional & scientific | 2024 |
| Ortholux Limited | Health & social care | 2020 |
| Osprey Ridge LP | | 2023 |
| Osteopaths for Industry Limited | Health & social care | 1987 |
| Otcysec Consultancy Limited | Information & communication | 2025 |
| Othello Investment (UK) Limited | Financial services | 2013 |
| Othello Properties Limited | Real estate | 2023 |
| Othello’S Collection LLP | | 2023 |
| Othen Enterprises Limited | Water & waste | 2022 |
| Ottis (UK) Limited | Financial services | 2011 |
| Ourbuk Ltd | Information & communication | 2020 |
| Outport Limited | Professional & scientific | 2025 |
| Over Exposed Ltd | Information & communication | 2015 |
| Over Exposed Property Ltd | Real estate | 2020 |
| OYB Investments Ltd | Real estate | 2015 |
| P a H Trading Limited | Wholesale & retail | 1985 |
| P50 Consulting Ltd | Other services | 2015 |
| Paces Blackhorse Ltd | Administrative & support | 2021 |
| Paces Greenwich Ltd | Administrative & support | 2025 |
| Paces Holdco RT Ltd. | Administrative & support | 2020 |
| Paces Holdings Ltd. | Administrative & support | 2020 |
| Paces Holdings PF Ltd | Administrative & support | 2020 |
| Paces Kingsway Ltd | Administrative & support | 2022 |
| Paces Leeds Ltd | Administrative & support | 2021 |
| Paces LPI Ltd | Hospitality | 2020 |