| Northallerton Specsavers Limited | Wholesale & retail | 1999 |
| Northampton Specsavers Hearcare Limited | Wholesale & retail | 2018 |
| Northampton Weedon Road Specsavers Limited | Wholesale & retail | 2017 |
| Northamptonshire Newmedica Limited | Health & social care | 2019 |
| Northend Retail Ltd | Wholesale & retail | 2012 |
| Northern Star VA Ltd | Administrative & support | 2021 |
| Northfield Specsavers Limited | Wholesale & retail | 1999 |
| Northfield Visionplus Limited | Wholesale & retail | 1999 |
| Northumberland Domi Audiology Specsavers Limited | Wholesale & retail | 2024 |
| Northwood (Romford) Limited | Real estate | 2000 |
| Northwood Symonds Limited | Financial services | 1999 |
| Norton Close (Southwick) Management Limited | Households | 2004 |
| Norton Specsavers Limited | Wholesale & retail | 2017 |
| Norwich 1 Domiciliary Specsavers Limited | Wholesale & retail | 2013 |
| Norwich Domi Audiology Specsavers Limited | Wholesale & retail | 2023 |
| Norwich New Build Snagging Ltd | Construction | 2007 |
| Norwich Pound Lane Specsavers Limited | Wholesale & retail | 2022 |
| Norwich Specsavers Limited | Wholesale & retail | 1993 |
| Norwich Visionplus Limited | Wholesale & retail | 1993 |
| Nostalgia Tea Rooms Limited | Hospitality | 2022 |
| NOT for Cats Ltd | Wholesale & retail | 2016 |
| Notimefoodie Ltd | Professional & scientific | 2026 |
| Nottingham Newmedica Limited | Health & social care | 2022 |
| Nottingham Specsavers Hearcare Limited | Wholesale & retail | 2003 |
| Nottingham Specsavers Limited | Wholesale & retail | 2003 |
| Nottingham Visionplus Limited | Wholesale & retail | 1999 |
| Nottinghamshire 2 Domiciliary Specsavers Limited | Wholesale & retail | 2014 |
| Nourish & Harmony Therapy Limited | Health & social care | 2025 |
| Nova Planning Limited | Professional & scientific | 2018 |
| Nova Planning Services Ltd | Professional & scientific | 2022 |
| Novatus Ltd | Real estate | 2010 |
| Novel Editing Limited | Information & communication | 2024 |
| Novicom Consulting Ltd | Information & communication | 2010 |
| Novus Design Ltd | Manufacturing | 2017 |
| NOW Legal LLP | | 2006 |
| Noyce Business Solutions Limited | Professional & scientific | 2022 |
| Noyce Enterprises Limited | Real estate | 2017 |
| Noyce Heating Ltd | Construction | 2020 |
| NP Administrative GP LLP | | 2016 |
| Npep Invest I LLP | | 2020 |
| NPM Consulting (UK) Ltd | Professional & scientific | 2012 |
| NR Supply Ltd | Administrative & support | 2022 |
| NRG1600 Consulting Limited | Administrative & support | 2018 |
| Nson Limited | Financial services | 2023 |
| NT (UK) Business Solutions Ltd | Information & communication | 2003 |
| Nubis Associates Limited | Information & communication | 2017 |
| Nuclear Technologies PLC | Professional & scientific | 1994 |
| Nugen Group Ltd | Real estate | 2020 |
| Nugen Properties Ltd | Construction | 2020 |
| Nulife Investments Ltd | Financial services | 2025 |
| Nulife Zumba Ltd | Arts & recreation | 2025 |
| Nulook Group Ltd | Construction | 2020 |
| Numberology Ltd | Professional & scientific | 2021 |
| Nuneaton Specsavers Hearcare Limited | Wholesale & retail | 2003 |
| Nurturing Minds Psychology Ltd | Health & social care | 2017 |
| NV Engineering Ltd | Construction | 2021 |
| Nwodo Asset Management Limited | Real estate | 2026 |
| Nwodo Ventures Limited | Real estate | 2017 |
| NWS Corporate Ltd | Financial services | 2024 |
| NXT Futures Ltd | Education | 2022 |
| NXT Group Ltd | Health & social care | 2021 |
| NXT Skills Ltd | Health & social care | 2020 |
| O Trewavas Engineering Ltd | Professional & scientific | 2026 |
| O&S Superstores Ltd | Wholesale & retail | 2026 |
| O'Neill Construction (Fareham) Limited | Construction | 1992 |
| O.M Beef Limited | Hospitality | 2026 |
| Oadby Specsavers Limited | Wholesale & retail | 2017 |
| Oak & Thread Ltd | Manufacturing | 2025 |
| Oak Court (Fareham) Management Services Limited | Households | 2001 |
| Oak Homes Ltd | Real estate | 2020 |
| Oak Tree Day Centre Ltd | Health & social care | 2026 |
| Oak Underwriting PLC | Financial services | 1999 |
| Oakbridge Agility Limited | Professional & scientific | 2026 |
| Oakham Specsavers Limited | Wholesale & retail | 2017 |
| Oakland Grove Limited | Wholesale & retail | 2025 |
| Oaklands Energy Ltd | Professional & scientific | 2010 |
| Oakleaf Property Company Limited | Real estate | 1979 |
| Oakridge Carpentry and Construction Limited | Construction | 2009 |
| Oakstone Property 1 Limited | Real estate | 2026 |
| Oaktree & Partners Ltd | Real estate | 2026 |
| Oakvista Limited | Construction | 2013 |
| Oakwood Specsavers Limited | Wholesale & retail | 2017 |
| OAN Travel Ltd | Professional & scientific | 2026 |
| Oasis Property Solutions Limited | Real estate | 2024 |
| Obam Limited | Construction | 2013 |
| Oban Specsavers Limited | Wholesale & retail | 2004 |
| Obelisk Power Systems UK Limited | Construction | 2016 |
| OBK Installations Ltd | Construction | 2019 |
| Obsequio Limited | Manufacturing | 2016 |
| OC Digital Ltd | Information & communication | 2013 |
| Occupational Hygienist Services Ltd | Professional & scientific | 2020 |
| Ocean Bathrooms London Ltd | Wholesale & retail | 2016 |
| Ocean Bathrooms.Com Limited | Wholesale & retail | 2003 |
| Ocean City Cars Ltd | Wholesale & retail | 2025 |
| Ocean City Property Investments Limited | Real estate | 2026 |
| Ocean Engineered Ltd | Manufacturing | 2023 |
| Ocean Environmental Limited | Construction | 1999 |
| Ocean Plaice (Fareham) Limited | Hospitality | 2021 |
| Ocean Safeguarding Ltd. | Administrative & support | 2016 |
| Ocean Views Residence Ltd | Real estate | 2022 |