| MK Plumbing Services Ltd | Households | 2026 |
| MKR Wholesale Supplies Ltd | Wholesale & retail | 2022 |
| ML Chambers Media Limited | Information & communication | 2026 |
| ML Woodchurch Limited | Hospitality | 2024 |
| MLC Capital Holdings Ltd | Financial services | 2025 |
| MLG Wagon Works Ltd | Transport & logistics | 2026 |
| MM Property Links Limited | Construction | 2023 |
| Mmcg Digital Limited | Professional & scientific | 2024 |
| Mmil Investments Limited | Real estate | 2020 |
| MMS London Properties Limited | Construction | 2016 |
| MN Cleaning Solution UK Ltd | Administrative & support | 2026 |
| Mncikigai Ltd | Professional & scientific | 2026 |
| MO Barber Birkenhead Ltd | Other services | 2025 |
| Mo'Mina NW Ltd | Hospitality | 2020 |
| Mobile Testing Solutions Ltd | Other services | 2013 |
| Mocan's Innovation Ltd | Transport & logistics | 2023 |
| Mode Mwah Limited | Manufacturing | 2014 |
| Modi Stores Limited | Wholesale & retail | 2014 |
| Modified Central Ltd | Professional & scientific | 2023 |
| Momentum Property Solutions Ltd | Professional & scientific | 2017 |
| Monaf Spice & Grill Ltd | Hospitality | 2019 |
| Mongkokcateringuk Ltd | Manufacturing | 2023 |
| Monsieurz Ltd | Wholesale & retail | 2026 |
| Montador Motor Engineers Ltd | Wholesale & retail | 2013 |
| Montahud Estates Ltd | Hospitality | 2019 |
| Montanablue Holdings Limited | Administrative & support | 2024 |
| Montanablue Limited | Administrative & support | 2013 |
| Moorcroft Electrical Services Ltd | Construction | 2022 |
| Moorfields Lets Ltd | Hospitality | 2019 |
| Mores Property Ltd | Real estate | 2023 |
| Moreton Alarms Supplies (MAS) Limited | Wholesale & retail | 2002 |
| Morpho Skin N Soul Ltd. | Manufacturing | 2023 |
| Moscrops Estate Agents Limited | Real estate | 2014 |
| Mosey Investments Ltd | Financial services | 2025 |
| Mosey Joynson Group Ltd | Financial services | 2024 |
| Mother Deli & Store Limited | Wholesale & retail | 2022 |
| Motion Picture Designs Ltd | Wholesale & retail | 2024 |
| Moto CJ Imports Limited | Wholesale & retail | 2026 |
| Motorcare (Powys) Limited | Wholesale & retail | 2004 |
| Mountwood Consulting Limited | Professional & scientific | 2025 |
| Moved Removals & Storage Limited | Transport & logistics | 2017 |
| MPE Interiors Holdings Limited | Financial services | 2024 |
| MPL Technologies Limited | Information & communication | 2026 |
| Mplifyd Consulting Limited | Information & communication | 2023 |
| MPS Security Limited | Administrative & support | 2000 |
| MR Waffle Desserts Ltd | Wholesale & retail | 2026 |
| MR Waffle Milkshakes Ltd | Hospitality | 2020 |
| MR Yummie Ltd | Hospitality | 2026 |
| MSH Partnership (UK) Limited | Professional & scientific | 2012 |
| MTN Installations and Security Ltd | Construction | 2017 |
| Mukund Limited | Health & social care | 2024 |
| Mums Care Ltd | Health & social care | 2019 |
| Munaza Group of Services Limited | Wholesale & retail | 2025 |
| Murphy's Construction and Development Ltd | Construction | 2016 |
| Murphy's Crow Flies Travel Ltd | Transport & logistics | 2025 |
| Murphys Airlink Ltd | Transport & logistics | 2010 |
| Muximus Ltd | Real estate | 2019 |
| MW Paving Ltd | Construction | 2025 |
| MW Sports C.I.C. | Education | 2014 |
| MWP Joinery Limited | Construction | 2025 |
| MX9 Ltd | Information & communication | 2003 |
| My Glass Ltd | Construction | 2024 |
| My Zing Limited | Hospitality | 2025 |
| N D Couriers Limited | Transport & logistics | 2020 |
| N W Trading Limited | Transport & logistics | 1999 |
| N&D Haus of Aesthetics Ltd | Other services | 2026 |
| N.M.L. Admin Services Ltd | Administrative & support | 2017 |
| N7K Limited | Wholesale & retail | 2021 |
| Nafs Ltd. | Wholesale & retail | 2025 |
| Naga Investments Limited | Real estate | 2021 |
| Naga PVT Limited | Wholesale & retail | 2019 |
| Nagaa Retails Ltd | Wholesale & retail | 2025 |
| Naic Investment Company | Financial services | 2021 |
| Nails by Sofia Lily Ltd | Other services | 2025 |
| Nails of Distinction Limited | Other services | 2003 |
| Nails Studio Brikenhead Ltd | Other services | 2023 |
| Naiso Investment Company | Financial services | 2022 |
| Nalyd Investment Company | Financial services | 2021 |
| Namax Capital Limited | Professional & scientific | 2022 |
| Namax Investments Limited | Professional & scientific | 2022 |
| Namax Properties Limited | Real estate | 2022 |
| Nathan John Ltd. | Real estate | 2017 |
| Nathan Moody Ltd | Real estate | 2023 |
| National PHS Group Ltd | Construction | 2026 |
| Natural Earth Limited | Wholesale & retail | 2023 |
| Natural Leaders Limited | Professional & scientific | 2009 |
| NB Recruitment Limited | Administrative & support | 2021 |
| NBA Transport Ltd | Transport & logistics | 2025 |
| ND Renovations Limited | Construction | 2024 |
| NDA Holdings Ltd | Real estate | 2026 |
| Neat Investments 2000 Limited | Wholesale & retail | 2002 |
| Need for Tunes Ltd | Wholesale & retail | 2025 |
| NEEN73 Ltd | Wholesale & retail | 2025 |
| Nefera Limited | Education | 2026 |
| Neil Hayes Painting & Decorating Limited | Construction | 2004 |
| Neil Menear Wealth Management Limited | Professional & scientific | 2011 |
| Nekonyan Ltd | Information & communication | 2017 |
| NELSONS2014 Limited | Wholesale & retail | 2019 |
| Neobohemia Limited | Wholesale & retail | 2022 |
| Neonatal Expert Limited | Professional & scientific | 2016 |