| Multiplex.Moneycard Ltd | Professional & scientific | 2010 |
| Multix Holding Ltd | Administrative & support | 2024 |
| Mumanyi Enterprises Limited | Wholesale & retail | 2025 |
| Mumology Movement Limited | Health & social care | 2019 |
| Mumtaz Kitchen Ltd | Hospitality | 2025 |
| Munchieskebab Ltd | Hospitality | 2025 |
| Mundays Caravan Parks Limited | Hospitality | 1954 |
| Mundus Group Ltd | Water & waste | 2021 |
| Munro Bowman Limited | Professional & scientific | 2023 |
| Munro Hughson Limited | Information & communication | 2009 |
| Munyamamina Healthcare Ltd | Health & social care | 2021 |
| Murat 10 Ltd | Real estate | 2026 |
| Murcia Management Limited | Professional & scientific | 2010 |
| Muscliff Primary School | Education | 2015 |
| Muscliffe Commercial Finance Limited | Financial services | 2022 |
| Museum of Contemporary Art Limited | Real estate | 1994 |
| Mushroom Marketing Limited | Professional & scientific | 2005 |
| Music IS Life Instrument Retail Limited | Wholesale & retail | 2010 |
| Musical Storybox Ltd | Education | 2022 |
| Musicality Ltd | Other services | 2009 |
| Musicon Ltd | Transport & logistics | 2024 |
| Muskoka Group Ltd | Construction | 2024 |
| Mustachio Holdings Limited | Financial services | 2025 |
| Mutual Securities Limited | | 1984 |
| Muwanguzi Price's Limited | Health & social care | 2021 |
| Muya Consultancy Ltd | Professional & scientific | 2021 |
| MV Coaching Limited | Professional & scientific | 2024 |
| MV Property Management Ltd | Real estate | 2026 |
| MVB Property Investments Ltd | Construction | 2026 |
| MW Group Holdings Limited | Financial services | 2016 |
| MW Holdings South West Limited | Professional & scientific | 2019 |
| MW9 Consultancy Ltd | Professional & scientific | 2023 |
| MWM Properties Ltd | Real estate | 2021 |
| MX Sales & Services Ltd | Wholesale & retail | 2022 |
| Mxjqnn Ltd | Professional & scientific | 2018 |
| My Bar and PUB Limited | Hospitality | 2023 |
| My BED Ltd | Professional & scientific | 2010 |
| My Car Coach Limited | Professional & scientific | 2011 |
| My Chef Catering Ltd | Hospitality | 2014 |
| My Club Web Services Limited | Information & communication | 2013 |
| My Connected Home Limited | Wholesale & retail | 2019 |
| My Credit Options Ltd | Financial services | 2026 |
| My Essential Goods Ltd | Wholesale & retail | 2026 |
| My Father Christmas Limited | Information & communication | 2010 |
| My Fire Door Limited | Households | 2023 |
| My House Key Properties Ltd | Real estate | 2024 |
| My Kind of Care Ltd | Health & social care | 2022 |
| My Laundry Ltd | Information & communication | 2023 |
| My Linh Tran Ltd | Information & communication | 2019 |
| My Month.Ai Limited | Information & communication | 2026 |
| My Movement Medicine C.I.C. | Health & social care | 2025 |
| My One Landlord Ltd | Hospitality | 2023 |
| My Perfect Garden Studio Ltd | Construction | 2022 |
| My Rackets Ltd | Administrative & support | 2017 |
| My Tech (London) Ltd | Wholesale & retail | 2022 |
| My Think Space Ltd | Professional & scientific | 2026 |
| My Training POD Ltd | Arts & recreation | 2023 |
| My Venue Assistant (Myva) Ltd | Administrative & support | 2024 |
| My VIP Shisha Ltd | Hospitality | 2025 |
| Mychatsworth Limited | Real estate | 2020 |
| Mydeas PVT Limited | Professional & scientific | 2018 |
| Myers Bond Ltd | Real estate | 2024 |
| MYF Festival UK Limited | Arts & recreation | 2022 |
| Myflo Ltd | Wholesale & retail | 2020 |
| Myfriend Ltd | Hospitality | 2024 |
| Myhi Limited | Wholesale & retail | 2024 |
| Myhome International Limited | Real estate | 2021 |
| Myjama Ltd | Wholesale & retail | 2019 |
| Mykey BH Ltd | Administrative & support | 2025 |
| Mykidneycoach Limited | Information & communication | 2026 |
| Myla Investments Ltd | Other services | 2025 |
| Mylexa Ltd | Transport & logistics | 2022 |
| Mylocal Drainage Services Ltd | Water & waste | 2025 |
| Mylu Limited | Construction | 2024 |
| Myplant Biotechnologies UK Ltd | Other services | 2018 |
| Myriam Kniveton Limited | Professional & scientific | 2012 |
| Myrtle Healthcare Limited | Administrative & support | 2020 |
| Mysa Coffee Ltd | Hospitality | 2024 |
| Mysteron Training & Security Limited | Extraterritorial | 2004 |
| Mythos Poole Ltd Ltd | Hospitality | 2025 |
| Mytribe Health Limited | Financial services | 2022 |
| Mytrip by Passenger Limited | Information & communication | 1995 |
| N G Richards Limited | Real estate | 2009 |
| N GUY Properties Ltd | Real estate | 2026 |
| N H Developments Limited | Construction | 1993 |
| N R Sharland & Co Limited | Professional & scientific | 2010 |
| N R Technology Enterprises Limited | Professional & scientific | 2026 |
| N Richards Property Ltd | Real estate | 2021 |
| N T Construction Limited | Construction | 2025 |
| N W Grainger Services Limited | Information & communication | 2020 |
| N Waters Ltd | Financial services | 2021 |
| N&M Property Investment Ltd | Real estate | 2018 |
| N&R GL Group Ltd | Construction | 2023 |
| N. S. Consult Limited | Construction | 1998 |
| N.C./J.O. Holding Co Limited | Financial services | 2016 |
| N.I.C.E. (New Independent Conference Experts) Limited | Administrative & support | 2000 |
| Nabaz & Nick Limited | Wholesale & retail | 2021 |
| Nabeka Teaching Limited | Education | 2024 |
| Nabla Electrical Limited | Construction | 2015 |
| Nabs Construction Ltd | Construction | 2011 |