| MPC Properties (Watford) Ltd | Real estate | 2021 |
| MPG Construction (Bucks) Limited | Construction | 2015 |
| MPR Elec Solutions Ltd | Construction | 2026 |
| MR Data Ltd | Manufacturing | 2022 |
| MR Minted Limited | Professional & scientific | 2009 |
| MR Zaza Limited | Hospitality | 2003 |
| MR76 Ltd | Information & communication | 2026 |
| MRH Business Services Limited | Transport & logistics | 2013 |
| Mrodan Limited | Professional & scientific | 2021 |
| MRS Global Ltd | Wholesale & retail | 2019 |
| MS Builders & Construction Ltd | Construction | 2019 |
| MS Cubed Ltd | Administrative & support | 2022 |
| MS Legal Consultants Ltd | Professional & scientific | 2020 |
| MS Professionals Ltd | Professional & scientific | 2022 |
| Ms-Domus Ltd | Construction | 2014 |
| MSA Accounting Ltd | Professional & scientific | 2022 |
| MSA Consultants Limited | Professional & scientific | 2010 |
| MSG2 Ltd | Real estate | 2025 |
| MSM Estate Ventures Ltd | Real estate | 2025 |
| MSS Nitrogen Limited | Administrative & support | 2010 |
| Msvich Properties & Investments Ltd | Real estate | 2024 |
| Msvich Residential Care Ltd | Health & social care | 2024 |
| MTD Transport Ltd | Transport & logistics | 2021 |
| MTF Properties Limited | Real estate | 2024 |
| MTJ Live Ltd | Wholesale & retail | 2023 |
| Mucksters Properties Ltd | Real estate | 2024 |
| Mudra Builders Ltd | Construction | 2026 |
| Mulberry Close Developments Limited | Households | 2021 |
| Mulberry Close Properties Limited | Real estate | 1980 |
| Mulberry Manor (Farsley) Management Company Limited | Real estate | 2016 |
| Mulberry Park (Poringland) Management Company Limited | Households | 2015 |
| Multicare Services (UK) Limited | Health & social care | 2020 |
| Multimode Marketing Limited | Professional & scientific | 2009 |
| Multitrade Continental Ltd | Transport & logistics | 2011 |
| Mumper and Button Ltd | Wholesale & retail | 2025 |
| Muqaisa Boutique Ltd | Wholesale & retail | 2026 |
| Muraspec Decorative Solutions Limited | Manufacturing | 1998 |
| Muraspec EOT Limited | Professional & scientific | 2024 |
| Muraspec Limited | Professional & scientific | 2012 |
| Murphy Property Limited | Real estate | 2011 |
| Murray's Butchers Ltd | Wholesale & retail | 2012 |
| Murray’S and Co. Equestrian and Country Supplies Ltd | Wholesale & retail | 2019 |
| Murville Consultancy Limited | Administrative & support | 2013 |
| Muse Advisory Group Limited | Financial services | 2019 |
| Muse Advisory Limited | Financial services | 2006 |
| Music at ST. Johns Limited | Other services | 2006 |
| Musicality Innovation Limited | Professional & scientific | 2014 |
| Musolini Ltd | Transport & logistics | 2017 |
| Mussel Music Management Ltd | Arts & recreation | 2023 |
| Must BE Live Music Ltd | Extraterritorial | 2021 |
| Mv-Motors Ltd | Wholesale & retail | 2012 |
| MVA Electrical Ltd | Construction | 2024 |
| MVP Holdings Ltd | Administrative & support | 2021 |
| MVP Limited | Construction | 2010 |
| MVU Services Ltd | Other services | 2018 |
| MVW Electrical Ltd | Construction | 2023 |
| MW Prestige Wheels Ltd | Wholesale & retail | 2021 |
| MWS Management Ltd | Information & communication | 2020 |
| MWS Salt Ltd | Water & waste | 2024 |
| MWY Installations Limited | Construction | 2015 |
| My Accountant Friend Limited | Professional & scientific | 2009 |
| My Accounting Friend Limited | Professional & scientific | 2009 |
| My AI Friend Limited | Information & communication | 2024 |
| My Behaviour Limited | Education | 2013 |
| My Big Greek Green Salad Ltd | Hospitality | 2021 |
| My Body Centre HH Limited | Arts & recreation | 2018 |
| My Club International Ltd | Administrative & support | 2022 |
| My Delivery Professional Ltd | Information & communication | 2025 |
| My Flight Zone Ltd | Administrative & support | 2026 |
| My LY Limited | Professional & scientific | 2016 |
| My Online Assistant Ltd | Administrative & support | 2025 |
| My Sparerooms Ltd | Households | 2021 |
| My Tax Planner Limited | Professional & scientific | 2025 |
| My Travel Agent Ltd | Administrative & support | 2026 |
| My World in Style Limited | Administrative & support | 2019 |
| My.Dar Ltd | Real estate | 2023 |
| MYB Direct Limited | Wholesale & retail | 2014 |
| Mycraft Limited | Households | 1994 |
| Mygirlscloset Ltd | Wholesale & retail | 2024 |
| Myic UK Ltd | Information & communication | 2014 |
| Myly&Oty Trans Ltd | Transport & logistics | 2019 |
| Mystic AI Limited | Manufacturing | 2019 |
| Mystic Lights Ltd | Health & social care | 2024 |
| N Carey Communications Limited | Professional & scientific | 2018 |
| N E Way Communicate Limited | Education | 2015 |
| N P&G Construction Ltd | Construction | 2017 |
| N R Doors Limited | Construction | 2018 |
| N&L Recruiting Ltd | Administrative & support | 2019 |
| N. HOW Limited | Administrative & support | 2021 |
| N.H.G. Accommodations Limited | Real estate | 1958 |
| N.P.S. Builders Limited | Construction | 1965 |
| N2 Properties Ltd | Real estate | 2024 |
| Naaa Properties Ltd | Real estate | 2025 |
| Nachalah Limited | Financial services | 2020 |
| Nad's Muddy Paws Ltd | Other services | 2025 |
| Nademiz Ltd | Hospitality | 2026 |
| Naijatutors Konnect Ltd | Education | 2023 |
| Nail JAM Ltd | Other services | 2025 |
| Naimon Limited | Administrative & support | 2023 |
| Naked Angels Ltd | Information & communication | 2021 |