| MBW Plumbing and Heating Ltd | Construction | 2026 |
| MC Design and Planning Ltd | Professional & scientific | 2026 |
| MC Dynamics Limited | Information & communication | 2024 |
| Mcannor Optical Ltd | Health & social care | 2015 |
| Mceg Services Limited | Education | 2024 |
| Mcgrigor Consulting Limited | Professional & scientific | 2014 |
| Mcgrigor Publishing Limited | Hospitality | 2014 |
| MCH Accountants Ltd | Professional & scientific | 2019 |
| MCH Software Solutions Ltd | Information & communication | 2021 |
| Mcpl Property Limited | Households | 2023 |
| MCR Autorepair Ltd | Wholesale & retail | 2021 |
| MCS Probuild Ltd | Construction | 2025 |
| Mdanaila Ltd | Wholesale & retail | 2024 |
| Mead Event Catering Limited | Hospitality | 2008 |
| Meat and VEG Company Ltd | Hospitality | 2021 |
| Mechwise Ltd | Information & communication | 2020 |
| Medic One EMS Limited | Health & social care | 2021 |
| Mediclinic PVT Ltd | Other services | 2022 |
| Medipharma Group Ltd | Financial services | 2016 |
| Medipharma Limited | Wholesale & retail | 1991 |
| Megamixfit Ltd | Arts & recreation | 2020 |
| Meon Hill Farms (Stockbridge) Limited | Real estate | 1990 |
| Merityre Properties Limited | Real estate | 1958 |
| Merityre Specialists Limited | Wholesale & retail | 1961 |
| Merlin Property Portfolio Limited | Real estate | 2025 |
| MET7 Limited | Transport & logistics | 2018 |
| Meticulous Movements Transport (MMT) Ltd | Transport & logistics | 2025 |
| Mezra Enterprise Ltd | Wholesale & retail | 2023 |
| MG Cavill & Co Services Ltd | Construction | 2023 |
| MH4.0 Training & Consulting Limited | Professional & scientific | 2018 |
| MHS Design Limited | Professional & scientific | 2016 |
| MHS Equities Limited | Financial services | 2020 |
| Miami Mobile Ltd | Wholesale & retail | 2019 |
| Mibranta Limited | Extraterritorial | 2015 |
| Michael Allen Limited | Professional & scientific | 2020 |
| Michael J Miles IC Limited | Financial services | 1987 |
| Mick Cooper Couriers Ltd | Transport & logistics | 2020 |
| Mickey- Transport Ltd | Transport & logistics | 2021 |
| Micra Services Ltd | Information & communication | 2024 |
| Micro Installation Services Limited | Information & communication | 1984 |
| Mide Property Solution Ltd | Real estate | 2022 |
| Midpoint Consultants Limited | Professional & scientific | 1996 |
| Mike and Warren Burgess Limited | Wholesale & retail | 2016 |
| Mike Pagett Limited | Construction | 2007 |
| Mike's Consultants Ltd | Administrative & support | 2016 |
| Miles Electronics Limited | Manufacturing | 1996 |
| Mills Marine Consultants Ltd | Transport & logistics | 2020 |
| Millway Heating and Plumbing Solutions Ltd | Construction | 2022 |
| Miltech Developments Limited | Wholesale & retail | 2002 |
| Milton Cable Management Systems Limited | Professional & scientific | 2018 |
| Milux Ltd | Information & communication | 2019 |
| Mimmi Healthcare Services Ltd | Health & social care | 2023 |
| Mind & Muscle (Andover) Limited | Manufacturing | 2017 |
| Mind of Baits Ltd | Wholesale & retail | 2023 |
| Mind Over Matter Ltd | Other services | 2026 |
| Minrva&Co Limited | Professional & scientific | 2025 |
| Mira Drinks Limited | Financial services | 2021 |
| Mirek Transport Ltd | Transport & logistics | 2021 |
| Miss DIG Ltd | Administrative & support | 2019 |
| Misskad Ltd | Wholesale & retail | 2025 |
| Mjph Ltd | Real estate | 2005 |
| MK Town Properties Ltd | Real estate | 2023 |
| MKC Associates Limited | Real estate | 1986 |
| Mkcx Limited | Transport & logistics | 2026 |
| MKS Engineering Services Ltd | Manufacturing | 2022 |
| ML Group Holdings Limited | Financial services | 2017 |
| MLC Enterprises Ltd | Hospitality | 2023 |
| Mmarepairsandcustom Ltd | Wholesale & retail | 2025 |
| MNB Roofing and Construction Ltd | Construction | 2022 |
| Mobile Enterprise Ltd | Information & communication | 2000 |
| Moco FX Ltd | Information & communication | 2015 |
| Modern Standard Coffee Limited | Manufacturing | 2014 |
| Modern Standard Service Limited | Wholesale & retail | 2018 |
| Modutreat Ltd | Manufacturing | 2025 |
| Moenviron Limited | Professional & scientific | 2025 |
| Molewell Holdings Limited | Financial services | 2023 |
| Momentum Netball Ltd | Education | 2024 |
| Momentum Sports Technology Ltd | Information & communication | 2026 |
| Monitorlux Limited | Information & communication | 2026 |
| Monkey Business Holdings Ltd | Financial services | 2020 |
| Monks Acre Management Company Limited | Administrative & support | 2005 |
| Monopolising Ltd | Professional & scientific | 2023 |
| Monster Tree Services Limited | Administrative & support | 2021 |
| Monte Rosa Capital Limited | Financial services | 2013 |
| Montgomery & Storm Investments Limited | Financial services | 2025 |
| Montgomery Scott Ltd | Financial services | 2023 |
| Montgomery Scott Services Ltd | Financial services | 2023 |
| Monxton & Grateley Golf Centre Ltd | Arts & recreation | 2020 |
| Mooch Trading Limited | Wholesale & retail | 2004 |
| Moores Maintenance Services Limited | Construction | 2017 |
| Mooreso Ltd | Health & social care | 2013 |
| More Good Times Limited | Information & communication | 2025 |
| Morph ICT Ltd | Information & communication | 2015 |
| Morris Rawnson & Taylor Group Limited | Financial services | 2018 |
| Mosaique Holistic Beauty & Image Limited | Other services | 2008 |
| Motive One SIX Ltd | Arts & recreation | 2024 |
| Moto-Lita Limited | Manufacturing | 1964 |
| Motorvate Limited | Wholesale & retail | 2006 |
| Mott. Estate Agents Limited | Real estate | 2025 |
| Movin Monkeez Limited | Arts & recreation | 2012 |