| Move Fast Storage Limited | Transport & logistics | 1996 |
| Move Nest Ltd | Transport & logistics | 2025 |
| Movie Mother Ltd | Information & communication | 2019 |
| Moving on UP Construction Limited | Construction | 2025 |
| Mower Master Limited | Manufacturing | 2025 |
| Mp-Mobile Ltd | Professional & scientific | 2025 |
| Mpaka Distributors Ltd | Wholesale & retail | 2025 |
| MPB Catering Ltd | Hospitality | 2025 |
| MPB LET Properties Ltd | Real estate | 2026 |
| MPH Assets Ltd | Real estate | 2023 |
| MPH Holdings Ltd | Financial services | 2023 |
| MPM Interior Solutions Limited | Other services | 2012 |
| Mpmis Limited | Construction | 2025 |
| MPS Business Supplies Limited | Wholesale & retail | 2018 |
| MPS Group Ltd | Wholesale & retail | 2024 |
| MR Assignment Ltd | Wholesale & retail | 2025 |
| MR Designs Ltd | Professional & scientific | 2025 |
| MR Fade Barbers Ltd | Other services | 2026 |
| MR Memory Limited | Extraterritorial | 2012 |
| MR. Crisp Limited | Wholesale & retail | 1993 |
| Mran Ltd | Wholesale & retail | 2013 |
| MRC Garden and Estate Management Limited | Hospitality | 2014 |
| Mrcd Pharma Services Limited | Professional & scientific | 2015 |
| MS Audio Ltd | Manufacturing | 2012 |
| MS International Holding Limited | Financial services | 2020 |
| MS Paving Ltd | Professional & scientific | 2025 |
| Msgm Ltd | Administrative & support | 2011 |
| MSP Consultancy Limited | Professional & scientific | 2018 |
| MT Food & Drink Ltd | Hospitality | 2017 |
| MT Social Studio Ltd | Information & communication | 2026 |
| MTM: Make the Most Ltd | Education | 2024 |
| Mtsm Ltd | Construction | 2023 |
| Muchas Music Ltd | Information & communication | 2019 |
| Mulberry Hollow Limited | Households | 2005 |
| Mulberry Park Estates Limited | Real estate | 2021 |
| Mulberry Property Investment Management Limited | Real estate | 2000 |
| Mulligan Brothers Holdings Ltd | Financial services | 2019 |
| Mulligan Brothers Ltd | Administrative & support | 2016 |
| Multipanel Fire Protection Limited | Public administration | 2023 |
| Multiplexx Technologies Limited | Administrative & support | 1995 |
| Multiversal Energy Ltd | Health & social care | 2019 |
| Munz Made IT Ltd | Information & communication | 2021 |
| Murch Road Creative Limited | Information & communication | 2021 |
| Murmuration Media Ltd | Information & communication | 2022 |
| Murrell Trading International Limited | Wholesale & retail | 2023 |
| Muscovado Ltd | Professional & scientific | 2018 |
| Musnai Ltd | Transport & logistics | 2020 |
| MVMT42 Limited | Arts & recreation | 2018 |
| Mwaruwari Limited | Information & communication | 2016 |
| Mwjh Legal Limited | Professional & scientific | 2025 |
| MX Metalworks Ltd | Manufacturing | 2020 |
| MX Steel Erectors Limited | Construction | 2017 |
| MXT Rydon Swimming School Limited | Arts & recreation | 2013 |
| My Barbers (London) Ltd | Other services | 2024 |
| My Body Jewellery Ltd | Extraterritorial | 2015 |
| My Estates Management Limited | Extraterritorial | 2015 |
| My Little Farm Holdings Limited | Financial services | 2026 |
| My Little Farm Sussex Holdings Limited | Financial services | 2026 |
| My Little Farm Sussex Operations Ltd | Financial services | 2026 |
| My Phone in Ltd | Wholesale & retail | 2024 |
| My Sales Limited | Financial services | 2015 |
| My Twentyeight Ltd | Wholesale & retail | 2024 |
| Mycapers Limited | Health & social care | 2010 |
| Mycrum Media Limited | Information & communication | 2013 |
| Mytappyplace Ltd | Information & communication | 2025 |
| Mzuli M Heating and Water Solutions Ltd | Other services | 2017 |
| N & L Seals Limited | Manufacturing | 2012 |
| N & R Webb Brickwork Limited | Construction | 2007 |
| N D Therapy Services Limited | Health & social care | 2024 |
| N Gatenby Consulting Limited | Professional & scientific | 2020 |
| N Property Investments Limited | Real estate | 2025 |
| N R Gatenby Construction Ltd | Construction | 2003 |
| N S Marine Limited | Administrative & support | 2001 |
| N W Computer Services Limited | | 2012 |
| N&T Livewire Ltd | Information & communication | 2019 |
| N-Kal Management Limited | Construction | 2021 |
| N.A. Petitt Builders Limited | Construction | 2003 |
| N.Burton Limited | Professional & scientific | 2011 |
| N.P.G. Home Grown Limited | Agriculture & fishing | 1980 |
| N23A Consulting Ltd | Professional & scientific | 2023 |
| N23A Ltd | Professional & scientific | 2023 |
| N8 Consulting Limited | Administrative & support | 2024 |
| N8 Media Ltd | Information & communication | 2019 |
| N8.BUSINESS Ltd | Professional & scientific | 2016 |
| Naail Amilah Holdings Limited | Real estate | 2016 |
| Nagu & Daughters Limited | Wholesale & retail | 2017 |
| Nagu & SON Ltd | Other services | 2017 |
| Nailed Down Properties Ltd | Real estate | 2025 |
| Naima Indian Takeaway Ltd | Hospitality | 2018 |
| Namesake Films Ltd | Information & communication | 2017 |
| Nana JAN Knits Ltd | Manufacturing | 2018 |
| Nanteos Developments Limited | Professional & scientific | 2015 |
| Narkose Limited | Health & social care | 2013 |
| Narnia Homes Ltd | Construction | 2023 |
| Narnoc Ltd | Professional & scientific | 2024 |
| Nasgp - National Association of Sessional GPS | Other services | 1999 |
| Nash Property 2017 LLP | | 2017 |
| Natalie O'Neill Limited | Information & communication | 2024 |
| Natalie Shering Ltd | Professional & scientific | 2019 |
| Nathan Burstow Ltd | Construction | 2026 |