| NR Fornax LLP | | 2019 |
| Nraj Investments Ltd | Financial services | 2021 |
| NRD Movers Ltd | Transport & logistics | 2023 |
| Nrma Accounting Ltd | Professional & scientific | 2020 |
| NS Consultancy and Management Ltd | Professional & scientific | 2021 |
| NS International Limited | Wholesale & retail | 1994 |
| NS Properties Limited | Real estate | 1990 |
| Nsgalore Ltd | Other services | 2024 |
| NSH Building Services Ltd | Construction | 2022 |
| NSH Ltd | Hospitality | 2026 |
| NSL Promotions Ltd | Professional & scientific | 2023 |
| Nsmv Property Holdings Ltd | Real estate | 2017 |
| NSR Property Investments Limited | Real estate | 2016 |
| NST Logistics Ltd | Transport & logistics | 2025 |
| Ntec (UK) Ltd | Construction | 2009 |
| Ntifo Enterprises Ltd | Water & waste | 2018 |
| Ntoni Consulting Limited | Real estate | 2016 |
| Ntoni Property Limited | Real estate | 2017 |
| NTR Property Limited | Real estate | 2026 |
| Ntra Construction Limited | Construction | 2022 |
| NU Addiscombe Limited | Wholesale & retail | 2015 |
| NU Addiscombe Property Limited | Real estate | 2021 |
| Nu-Shine Residential Limited | Administrative & support | 2017 |
| Nubooks Limited | Information & communication | 2020 |
| Nudge Factory Ltd | Professional & scientific | 2011 |
| Nuevo Wellness Limited | Arts & recreation | 2021 |
| Nugent Strategies Limited | Wholesale & retail | 2026 |
| Number Management Limited | Professional & scientific | 2011 |
| Number Ninety-Two Tenants Association Limited | Households | 1963 |
| Number One Business Limited | Transport & logistics | 2020 |
| Numtech Business Services Limited | Professional & scientific | 2018 |
| Nunnery Fields (Management NO.1) Limited | Households | 2005 |
| Nunnery Fields (Management) Limited | Households | 2004 |
| Nunu Construction Ltd | Real estate | 2013 |
| NUP Addiscombe Limited | Wholesale & retail | 2026 |
| Nurash Associate Ltd | Manufacturing | 2019 |
| Nuredini Properties Limited | Real estate | 2025 |
| Nuronyx Ltd | Administrative & support | 2023 |
| Nuten Limited | Real estate | 2020 |
| Nutfield Contractors NW Ltd | Construction | 2019 |
| Nutfield Contractors SW Ltd | Construction | 2019 |
| Nutley's Kitchen Gardens Ltd | Wholesale & retail | 2006 |
| Nutra Supplements Ltd | Wholesale & retail | 2022 |
| Nutrifix Health Ltd | Wholesale & retail | 2018 |
| Nutrigenic Group Limited | Manufacturing | 2025 |
| Nutriharvest CIC | Hospitality | 2025 |
| Nutrition for Thought Ltd | Health & social care | 2021 |
| Nuts for... Limited | Information & communication | 2004 |
| Nuush Solutions Ltd | Information & communication | 2006 |
| Nuvantis Group Limited | Information & communication | 2024 |
| NV Plumbing Ltd | Construction | 2018 |
| Nventors Ltd | Information & communication | 1998 |
| Nvubu Limited | Real estate | 2025 |
| Nwanyinnewi Nigerian Home Kitchen Limited | Hospitality | 2025 |
| NWL Radiology Limited | Health & social care | 2016 |
| NWS Consultants Limited | Professional & scientific | 2022 |
| Nxgen Computers | | 1993 |
| Nyamekye's Kitchen Ltd | Hospitality | 2022 |
| NYR Properties Limited | Real estate | 2021 |
| Nysa Investments Ltd | Professional & scientific | 2023 |
| NZS Medicals Ltd | Health & social care | 2018 |
| NZS Property Limited | Real estate | 2020 |
| O & a EPM Ltd | Real estate | 2017 |
| O D Empire Limited | Wholesale & retail | 2024 |
| O T Callout Services Limited | Other services | 2021 |
| O' Maranese Ltd | Hospitality | 2024 |
| O'Brien Haulage Services Ltd. | Construction | 2016 |
| O'Connor Sokolowski Partners Ltd | Professional & scientific | 2012 |
| O'Kelzcollections Ltd | Professional & scientific | 2026 |
| O'Neill Surveying Services Ltd | Professional & scientific | 2014 |
| O'Red Care Solution Limited | Health & social care | 2021 |
| O'Sullivan Civil Engineering Limited | Construction | 2000 |
| O'Sullivan Management Company Limited | Administrative & support | 2008 |
| O.K Bailey Limited | Construction | 2014 |
| O.K.Build Solution Ltd | Construction | 2025 |
| O.P. Catering Limited | Hospitality | 2005 |
| O.Z Property Ltd | Administrative & support | 2012 |
| Oak After-School Care Limited | Health & social care | 2025 |
| Oak Court (1995) Limited | Households | 1996 |
| Oak Financial Management Ltd | Financial services | 2010 |
| Oak Green Management Company Limited | Households | 2005 |
| Oak Heights (Northiam) Residents Management Company Limited | Households | 2016 |
| Oak Hill Mews Management Company Limited | Households | 2016 |
| Oak Mount Management Company (UK) Limited | Households | 2002 |
| Oak Nest Children's Homes Ltd | Health & social care | 2023 |
| Oak Terrace Properties Ltd | Real estate | 2018 |
| Oak Tree Drive (Guildford) Management Company Limited | Households | 2007 |
| Oak View RTM Company Limited | Households | 2024 |
| Oak-Company Ltd | Financial services | 2016 |
| Oakbank (Prestwich) Management Limited | Households | 1988 |
| Oakcroft Care Limited | Financial services | 2016 |
| Oakdale (Updown Hill) Management Company Limited | Households | 2003 |
| Oakdene Finishes Limited | Administrative & support | 2010 |
| Oakfield Contractors and Decorators Limited | Construction | 2011 |
| Oakfield Court Limited | Households | 2002 |
| Oakfields Care Limited | Financial services | 2003 |
| Oakfirst Limited | Construction | 1992 |
| Oakfleet 2000 Limited | Arts & recreation | 1999 |
| Oakhurst (Balsall Common) NO1 Management Company Limited | Households | 2001 |
| Oakhurst (Christchurch) Management Limited | Real estate | 2001 |