| MR Simms Henley Ltd | Wholesale & retail | 2020 |
| MS Medical Practice Ltd | Health & social care | 2023 |
| MSS Financial Ltd | Professional & scientific | 2025 |
| MTL Technical Services Ltd | Information & communication | 2025 |
| Muddy Productions Limited | Arts & recreation | 2013 |
| Mulberry Place (Witney) Management Company Limited | Households | 2008 |
| Multi-Tip Designs Limited | Extraterritorial | 2004 |
| Muntjac Limited | Professional & scientific | 1996 |
| Mvdb Property Investments Ltd | Real estate | 2024 |
| MVP Management Ltd | Professional & scientific | 2009 |
| MW Business Development Limited | Financial services | 2021 |
| MW Home Farm Ltd | Agriculture & fishing | 2024 |
| MWA Projects Group Limited | Financial services | 2024 |
| MWA Projects Limited | Professional & scientific | 2002 |
| MYZ London Ltd | Construction | 2025 |
| N-Tegra (UK) Limited | Information & communication | 2003 |
| NA Enterprises London Ltd | Wholesale & retail | 2013 |
| Naked Planet Ltd | Wholesale & retail | 2018 |
| Narragansett Limited | Real estate | 2020 |
| Narwhal Technologies UK Limited | Information & communication | 2019 |
| NASH2MEDIA Limited | Information & communication | 2003 |
| Natural Earth Plasters Ltd | Construction | 2016 |
| Nature's Kisses Limited | Health & social care | 2014 |
| Naughty Mutt Nice Limited | Wholesale & retail | 2016 |
| Navigate Performance Limited | Professional & scientific | 2022 |
| Nebu Group Ltd | Professional & scientific | 2025 |
| Nectar Talent Solutions Limited | Administrative & support | 2024 |
| Neejam 165 Limited | Construction | 1993 |
| Neil Powell Land and Property Ltd | Real estate | 2011 |
| Nesdtz Limited | Real estate | 2024 |
| NET Lofts Residents Management Company Limited | Households | 1998 |
| Nettlebed Creamery Limited | Manufacturing | 2013 |
| Nettlebed Holdings Ltd | Real estate | 2022 |
| Neuro-Procare Limited | Health & social care | 2014 |
| New Barn Place Management Company Limited | Households | 2000 |
| New Horizon Deliveries Ltd | Information & communication | 2024 |
| New Leys Court (Witney) Management Company Limited | Households | 2012 |
| Newark Capital Ltd | Financial services | 2024 |
| Newlyn Contact Centre Services Limited | Professional & scientific | 1999 |
| Newlyn Group EOT Trustees Limited | Financial services | 2025 |
| Newlyn Group Holding Ltd | Administrative & support | 2018 |
| Newlyn PLC | Administrative & support | 1999 |
| Newnham Hill Consultants Limited | Professional & scientific | 2012 |
| NFG Finance Limited | Financial services | 2016 |
| NFG Holdings Limited | Wholesale & retail | 2015 |
| Niagara Midco 2 Limited | Financial services | 2021 |
| Niblie Limited | Information & communication | 2026 |
| Nicola Taylor Consulting Ltd | Professional & scientific | 2025 |
| Niels Dagless Solicitors Limited | Professional & scientific | 2026 |
| Nigel Sheldon Limited | Information & communication | 2015 |
| Nightingale Gardens (Moreton) Management Company Limited | Households | 2021 |
| Niki Schafer Interior Design Ltd | Administrative & support | 2009 |
| Ninetysix Holdings Limited | Construction | 2024 |
| Nomorestrobe Ltd | Professional & scientific | 2025 |
| Nomos Expert Reports LLP | | 2023 |
| Nordyx Scientific Ltd | Professional & scientific | 2026 |
| Norspring Development Limited | Construction | 2016 |
| Norspring Properties Ltd | Real estate | 2021 |
| North Star Leadership Consulting Ltd | Professional & scientific | 2021 |
| Northfield END Food & Wine Limited | Wholesale & retail | 2024 |
| Northforma Entertainment Ltd. | Information & communication | 2015 |
| Northridge Way Management Company Limited(The) | Real estate | 1983 |
| Notch Furniture Ltd | Manufacturing | 2016 |
| Noted Productions Ltd | Arts & recreation | 2026 |
| November Financial Services Limited | Financial services | 2004 |
| NTL Biocell Limited | Manufacturing | 2022 |
| NTL Biologica Limited | Manufacturing | 2015 |
| NTL Subco 2017 Limited | Professional & scientific | 2017 |
| Nubodi Pilates Limited | Other services | 2019 |
| Numerically Ltd | Professional & scientific | 2017 |
| Nurture Care Holdings Limited | Health & social care | 2024 |
| Nutrifuel Ltd | Wholesale & retail | 2025 |
| Nuvo Pharma Ltd | Professional & scientific | 2021 |
| Nzuri Sana Accessories Ltd | Wholesale & retail | 2020 |
| O a M Projects Limited | Professional & scientific | 2007 |
| O'Neil Project Management Limited | Information & communication | 2007 |
| Oak Legal Group Ltd | Professional & scientific | 2026 |
| Oakfields Renovations Limited | Construction | 2024 |
| Oakstone International Holdings Ltd | Administrative & support | 2026 |
| Oakwood Howe Consulting Ltd | Professional & scientific | 2020 |
| Objective Communications Limited | Extraterritorial | 2004 |
| Occasio Managed Services Limited | Administrative & support | 2023 |
| Oceanwide Limited | Professional & scientific | 2023 |
| Ocgd Online Limited | Education | 2009 |
| Ocsb Limited | Real estate | 2026 |
| Octant Consulting Limited | Professional & scientific | 2014 |
| Octavia Mews Residents Association Limited | Real estate | 2006 |
| Offer More Options Limited | Financial services | 2011 |
| Ohpm RTM Company Limited | Households | 2025 |
| Ollie Phillips Limited | Information & communication | 2014 |
| Olney Court Management Company Limited | Households | 2004 |
| Olympus Tutoring Ltd | Education | 2026 |
| Omalime Limited | Administrative & support | 1977 |
| Omnipath.Ai Ltd | Information & communication | 2022 |
| One Delorme Street Management Company Limited | Real estate | 2005 |
| One Health RIS AI Technologies Accelerator Limited | Professional & scientific | 2023 |
| One Louder Productions Limited | Information & communication | 2024 |
| Onework Consulting Limited | Professional & scientific | 2019 |
| Oparo Social 1 Ltd | Other services | 2020 |
| Oparo Social 1A Limited | Construction | 2020 |