| Millgarden Estates Ltd | Hospitality | 2015 |
| Mimase Limited | Professional & scientific | 2017 |
| Mindful Reputation Limited | Professional & scientific | 2018 |
| Minerva Regulatory Consulting Limited | Professional & scientific | 2026 |
| Minster Design and Construction Limited | Construction | 2002 |
| Mirador Capital Holdings Limited | Financial services | 2024 |
| Miramar Security Limited | Administrative & support | 2010 |
| Misk Consultancy and Project Management Ltd | Professional & scientific | 2022 |
| Mislex (318) Limited | Professional & scientific | 2001 |
| Mission Adventure Community CIC | Education | 2025 |
| Mistweave Media Limited | Information & communication | 2015 |
| Mitchell Evans LLP | | 2009 |
| MK Tunnelling Limited | Professional & scientific | 2019 |
| ML Powell Ltd | Professional & scientific | 2024 |
| Mmjr LLP | | 2025 |
| MNA Creative Ltd | Information & communication | 2010 |
| Mobile Motorhome Maintenance Ltd | Wholesale & retail | 2026 |
| Mockingbird UK Tour Limited | Arts & recreation | 2024 |
| Modal Data Limited | Professional & scientific | 2016 |
| Molemba Limited | Construction | 2017 |
| Momentum Cloud AI Ltd | Information & communication | 2023 |
| Monika the Label Limited | Wholesale & retail | 2020 |
| Monty&Ridge Ltd | Wholesale & retail | 2021 |
| Monument Media Limited | Information & communication | 2011 |
| Mooveroo Ltd | Information & communication | 2026 |
| Moran Property and Electrical Services Ltd | Manufacturing | 2021 |
| More to Life Coach Ltd | Other services | 2024 |
| MORE2SCREEN Limited | Information & communication | 2006 |
| Morian Ltd | Real estate | 2016 |
| Morpheus Fluid Ltd | Information & communication | 2023 |
| Morphis Design Limited | Professional & scientific | 2017 |
| Morrelly Limited | Administrative & support | 2025 |
| Mortimore Designs Ltd | Wholesale & retail | 2019 |
| Mosaic Management Consultancy Ltd | Professional & scientific | 2025 |
| Motivational Maps Limited | Administrative & support | 2006 |
| Motormotion Ltd | Arts & recreation | 2018 |
| Motte and Bailey Construction Ltd | Construction | 2008 |
| Moukie Design Limited | Professional & scientific | 2012 |
| Mount House Godalming Limited | Households | 2002 |
| Mountain Dynamics International Ltd | Administrative & support | 2024 |
| Movarai Ltd | Information & communication | 2026 |
| Moveformal Property Management Limited | Administrative & support | 1994 |
| Moxie MOO Limited | Professional & scientific | 2024 |
| Moyo Partners Limited | Information & communication | 2026 |
| Mref Allegra Care Holdings Limited | Health & social care | 2022 |
| MRS Holdings Limited | Financial services | 2024 |
| MSB Design Ltd | Professional & scientific | 2021 |
| Msdp Developments Ltd | Construction | 2021 |
| MTJ3 Wealth Property Investor Ltd | Real estate | 2024 |
| Multiversant Ltd | Information & communication | 2018 |
| Munstead Horse Trials Ltd | Arts & recreation | 2015 |
| Murray Greenan Ltd | Other services | 2014 |
| Mush CR8TIVE Ltd | Information & communication | 2025 |
| Mushroom House Projects Ltd | Hospitality | 2025 |
| MW Psychology Ltd | Health & social care | 2023 |
| My Blue Rose Limited | Wholesale & retail | 2019 |
| My Physio London Ltd | Health & social care | 2010 |
| Myfootprint CIC | Education | 2013 |
| MYN Jazeel Consulting Limited | Professional & scientific | 2024 |
| Myparty Ltd | Wholesale & retail | 2010 |
| Myvytalcare Limited | Health & social care | 2018 |
| MZ Decorations Limited | Construction | 2012 |
| N a Berrill Limited | Information & communication | 2018 |
| N N Traders Ltd | Wholesale & retail | 2018 |
| N R Diamond Productions Ltd | Information & communication | 2016 |
| N R Sampson Limited | Professional & scientific | 2023 |
| N-Select Limited | Professional & scientific | 2001 |
| Nabava Consulting Ltd | Professional & scientific | 2023 |
| National Society Against Factory Farming Limited(The) | Other services | 1977 |
| Natter Cafe Limited | Hospitality | 2015 |
| Natural Data Insight Ltd | Information & communication | 2017 |
| Natural Habitat Developments Limited | Construction | 2002 |
| Natural Habitat Finance Limited | Construction | 2008 |
| Natural Products Factory Ltd | Manufacturing | 2011 |
| Nature's Ideas Limited | Arts & recreation | 2016 |
| Natures Partner Ltd | Hospitality | 2019 |
| NAU Limited | Information & communication | 2006 |
| Navicula Ltd | Administrative & support | 2019 |
| Navitas Brokers Limited | Financial services | 2011 |
| Navitas Management Services Limited | Financial services | 2009 |
| NCM Property Group Ltd | Real estate | 2023 |
| NDB Legal Consulting Ltd | Professional & scientific | 2014 |
| Nebula Programmes Limited | Information & communication | 2023 |
| Nectar Verde Ltd | Wholesale & retail | 2026 |
| Need to Know Digital Limited | Information & communication | 2011 |
| Neil MRU Ltd | Health & social care | 2022 |
| Neo-Tel Limited | Other services | 2004 |
| Neom Coaching Ltd | Education | 2023 |
| Neon Minnow Ltd. | Professional & scientific | 1999 |
| Nest Home and Cafe Limited | Wholesale & retail | 2012 |
| Netherley Property Co Limited | Real estate | 1962 |
| Netherwood Court Management Company Limited | Households | 1970 |
| New Start Systems Ltd | Information & communication | 2019 |
| Newnes-Smith Consulting Ltd | Professional & scientific | 2022 |
| Newsham Gray Ltd | Construction | 2025 |
| Nextred Ltd | Information & communication | 2014 |
| NF Care Holdings Limited | Health & social care | 2020 |
| Niall Mcconkey Limited | Professional & scientific | 2006 |
| Niche MHS Ltd | Real estate | 2012 |
| Niche PCM Limited | Hospitality | 2017 |