| Multi Trade Builders Ltd | Administrative & support | 2025 |
| Multidata and Electrical Limited | Construction | 2020 |
| Multiphase Flow Technologies Ltd | Professional & scientific | 2012 |
| Mulvihill Academy Group Limited | Arts & recreation | 2024 |
| Mulvihill Academy of Irish Dance Limited | Arts & recreation | 2010 |
| Munich 72 Trophies & Engraving Limited | Administrative & support | 2008 |
| Munnelly Sales Ltd | Information & communication | 2019 |
| Mura Consulting Ltd | Information & communication | 2012 |
| Murray Downs Freehold Limited | Households | 2020 |
| Murray Lift Group Limited | Financial services | 2015 |
| Murray Lift Maintenance Limited | Construction | 2015 |
| Murray Lift Services Limited | Manufacturing | 2005 |
| Murray Mobility Limited | Manufacturing | 2015 |
| Mushroom Media Services Limited | Professional & scientific | 2023 |
| Music Crowns Group Limited | Financial services | 2017 |
| Music for Joy Ltd | Education | 2025 |
| Musictime UK Limited | Administrative & support | 1997 |
| Mussell Group Ltd | Professional & scientific | 2024 |
| Muttley BOO Limited | Wholesale & retail | 2021 |
| Mvpl Limited | Transport & logistics | 2024 |
| MW Consultancy (London) Limited | Administrative & support | 2019 |
| My Home Competitions Ltd | Information & communication | 2025 |
| My Home PA Ltd | Administrative & support | 2025 |
| My Home PS Ltd | Construction | 2024 |
| My Mom's Recipe Ltd | Hospitality | 2026 |
| Mybc Limited | Construction | 2024 |
| Myed Fire & Construction Limited | Manufacturing | 2021 |
| Myeyehealth Ltd | Health & social care | 2025 |
| Mypowerhouse Limited | Transport & logistics | 2024 |
| Myria Marketing Ltd | Professional & scientific | 2026 |
| Myvouchers Limited | Administrative & support | 2019 |
| Mōrena Coffee Ltd | Hospitality | 2023 |
| N & S London Limited | Hospitality | 2020 |
| N a Butler Ltd | Manufacturing | 2011 |
| N P & M Ltd | Construction | 2024 |
| N S Access International Limited | Construction | 2017 |
| Naab Assets Limited | Administrative & support | 2002 |
| NAHUK1 Limited | Professional & scientific | 2022 |
| Nails Spa Blackfen Limited | Other services | 2025 |
| Nails UK (Blackfen) Limited | Other services | 2023 |
| NAJ Carpentry Limited | Construction | 2007 |
| Nana Berchie Limited | Arts & recreation | 2026 |
| Napier (OPS) Limited | Real estate | 2023 |
| Narz Consultancy Limited | Professional & scientific | 2020 |
| Nasenbatti's Limited | Health & social care | 2015 |
| Nash Build Limited | Construction | 2025 |
| Nateldaa Limited | Health & social care | 2020 |
| Native French Teachers (Private Tuition) Limited | Administrative & support | 1997 |
| Natural Light Installations Ltd | Administrative & support | 2023 |
| Naveed Syed and Associates Limited | Health & social care | 2011 |
| Nazzkeys Properties Ltd | Real estate | 2023 |
| NBN Design Ltd | Wholesale & retail | 2025 |
| NBR Electrical Ltd | Construction | 2021 |
| NC Bailey Developments & Services Limited | Real estate | 2017 |
| NCC Surveying Limited | Professional & scientific | 2022 |
| NCC Surveying Services Limited | Administrative & support | 2026 |
| ND Football Agents Ltd | Arts & recreation | 2020 |
| Ndidi Kareem Feruke-Bello CIC | Education | 2025 |
| Ndpatel Ltd | Real estate | 2021 |
| Neat Control Systems Limited | Professional & scientific | 2015 |
| Nebo Group Limited | Manufacturing | 2025 |
| Nectarine House Ltd | Wholesale & retail | 2022 |
| NED Siuipys Lighting Ltd | Arts & recreation | 2025 |
| Nedeoglo Ltd | Construction | 2018 |
| Nedleif Limited | Professional & scientific | 2018 |
| Needham RTM & Property Services Limited | Real estate | 2025 |
| Neil Convey Limited | Other services | 2014 |
| NEJ Catering Limited | Professional & scientific | 2018 |
| Nekkanti Solutions Limited | Information & communication | 2014 |
| Nelson Cleaning Ltd | Administrative & support | 2025 |
| Nelson Family Transport Ltd | Transport & logistics | 2022 |
| Neocad Limited | Professional & scientific | 2007 |
| Neon Electric London Ltd | Arts & recreation | 2022 |
| Nephi Construction Limited | Real estate | 2001 |
| Nest and Cozy Ltd | Wholesale & retail | 2024 |
| Netherhall Management Company (Sidcup) Limited | Households | 1995 |
| Netorg Limited | Information & communication | 2011 |
| Netstrata Ltd | Professional & scientific | 2016 |
| Nettle Homes Limited | Real estate | 2025 |
| Neuro Shroom Ltd | Manufacturing | 2024 |
| Neutron Solutions Limited | Administrative & support | 2011 |
| Neves Garage Limited | Wholesale & retail | 1956 |
| Neves Test Centre Limited | Wholesale & retail | 2020 |
| New Chapter Cleaning Services Ltd | Administrative & support | 2018 |
| New Eltham Dance School Ltd | Arts & recreation | 2017 |
| New England UK Limited | Other services | 2004 |
| New Generation Church Trust | Other services | 2006 |
| New Generation IT Service Ltd | Information & communication | 2025 |
| New Generation Schools Trust | Education | 2012 |
| New Landscape Ltd | Real estate | 2018 |
| New Leaf Electrical Limited | Construction | 2019 |
| New London Barbers Limited | Other services | 2021 |
| New Look Building Services Limited | Professional & scientific | 2005 |
| New Look Building Solutions Limited | Construction | 2016 |
| New Tech Building Services Ltd | Administrative & support | 2017 |
| New World Peking Ltd | Hospitality | 2018 |
| Newark Ltd | Information & communication | 2011 |
| Newco 2012 Limited | Construction | 2012 |
| Newlands IT Limited | Information & communication | 2017 |
| Newmark Services Ltd | Professional & scientific | 2021 |