| Mhelrose Limited | Health & social care | 2025 |
| MIA Horton Interiors Ltd | Professional & scientific | 2025 |
| Miaro Property Limited | Real estate | 2021 |
| Michelle Alexander Aesthetics Limited | Health & social care | 2015 |
| Microsyn Limited | Wholesale & retail | 2013 |
| Middleton Consultancy(Nw) Ltd | Professional & scientific | 2023 |
| MIG Creative Ltd | Professional & scientific | 2022 |
| Migglefinger Clothing Ltd | Wholesale & retail | 2022 |
| Mike Green Furniture Transport Limited | Transport & logistics | 2019 |
| Mike Staniforth Film Ltd | Administrative & support | 2017 |
| Milanov Medical Ltd | Health & social care | 2024 |
| Milesi Property Group Ltd | Real estate | 2019 |
| Mill (Union Road) Management Limited | Households | 1998 |
| Millennium Micros (Altrincham) Limited | Wholesale & retail | 2008 |
| Millennium Micros (Sale) Ltd | Wholesale & retail | 2011 |
| Millway Homes Limited | Real estate | 2020 |
| Minerva House Management (Notts) Ltd | Real estate | 2019 |
| Mini Soil Surveys UK Limited | Construction | 2022 |
| Minikin Designs Ltd | Arts & recreation | 2010 |
| Mint Comms Ltd | Administrative & support | 2017 |
| Mint Deck Limited | Wholesale & retail | 2026 |
| Minute Book Limited | Administrative & support | 2026 |
| Miraya Medics Limited | Health & social care | 2026 |
| Misu Tiramisu Limited | Wholesale & retail | 2025 |
| Mitch Fash Limited | Information & communication | 2020 |
| Mitchell's Online Ltd | Professional & scientific | 2022 |
| MIX Solutions Limited | Information & communication | 2013 |
| MJ Altibi Consultancy Services Limited | Health & social care | 2022 |
| MJ Badham Construction Limited | Construction | 2025 |
| MJ Daly Electrical Limited | Construction | 2018 |
| MJ Powell Consulting Ltd | Administrative & support | 2022 |
| MJ43 Limited | Financial services | 2025 |
| MJU Traders Ltd | Wholesale & retail | 2023 |
| MK Film Service Ltd | Professional & scientific | 2025 |
| MK Lighting Ltd | Professional & scientific | 2018 |
| MK Mechanical Ltd | Construction | 2024 |
| MK Retail Stores Ltd | Wholesale & retail | 2024 |
| MKB Surfacing and Groundworks Limited | Other services | 2023 |
| MKI Building Services Ltd | Construction | 2019 |
| ML Building & Maintenance Ltd | Construction | 2011 |
| ML Process Consultancy Ltd | Professional & scientific | 2017 |
| ML Software Limited | Extraterritorial | 2014 |
| Mlem Consulting Ltd | Professional & scientific | 2024 |
| MLH Bridgewater Physiotherapy Clinic Ltd. | Health & social care | 2010 |
| MLK Global Ltd | Wholesale & retail | 2025 |
| MLK GLOBAL1 Ltd | Wholesale & retail | 2023 |
| MMA Auto Assist Limited | Professional & scientific | 2025 |
| MMR Properties (NW) Ltd | Real estate | 2022 |
| MN Hosiery Limited | Construction | 2018 |
| Mo's Palace Redcar Ltd | Hospitality | 2020 |
| Mobilemeeting Ltd | Information & communication | 2024 |
| MOC Health Limited | Health & social care | 2023 |
| Moda Fide Ltd | Wholesale & retail | 2026 |
| Moda Flooring Limited | Construction | 2022 |
| Moda Investments Limited | Real estate | 2022 |
| Modern Trend Carpets Limited | Wholesale & retail | 2023 |
| Moffatt Accountancy Limited | Professional & scientific | 2003 |
| Moforless Limited | Administrative & support | 2003 |
| Mogantics Limited | Information & communication | 2020 |
| Mohammed Uddin Ltd | Health & social care | 2021 |
| Moiz Consultancy Ltd | Health & social care | 2026 |
| Moko Properties Ltd | Real estate | 2019 |
| Molepharma PVT Ltd | Wholesale & retail | 2021 |
| Molo Construction Limited | Construction | 2020 |
| Molo Hotel Group Limited | Financial services | 2017 |
| Molo Hotels (Barbados) Limited | Financial services | 2018 |
| Molo Hotels (Cambridge West) Limited | Hospitality | 2017 |
| Molo Hotels (Edinburgh) Limited | Construction | 2015 |
| Molo Hotels (Inverness) Limited | Construction | 2016 |
| Molo Hotels (Liverpool) Limited | Hospitality | 2018 |
| Molo Hotels (London Luton) Limited | Construction | 2016 |
| Molo Hotels (Luton) 2 Limited | Construction | 2016 |
| Molo Hotels (Manchester M4) Limited | Construction | 2019 |
| Moment of Grace Films Limited | Information & communication | 2021 |
| Monarch Associates | | 1997 |
| Moneva Evaluations Ltd | Financial services | 2025 |
| Montre Parfaite Ltd | Wholesale & retail | 2019 |
| Moobi Group Limited | Professional & scientific | 2023 |
| Moon Solutions Ltd | Information & communication | 2010 |
| More Insight UK Ltd | Professional & scientific | 2016 |
| More Media Sales Ltd | Professional & scientific | 2006 |
| More Than a Match Limited | Information & communication | 2025 |
| Morgan Financial Recruitment Limited | Administrative & support | 2005 |
| Moss Farm Management Company Limited | Households | 2023 |
| Moss Lane Farm Limited | Real estate | 2022 |
| Mossbank Financial Planning Limited | Financial services | 2014 |
| Motivateme Limited | Wholesale & retail | 2020 |
| Mould Services Limited | Water & waste | 2019 |
| Mount Property (York) Limited | Construction | 2012 |
| Move PR Limited | Professional & scientific | 2017 |
| Movie Wingman Limited | Information & communication | 2018 |
| Moxie Design Ltd | Professional & scientific | 2015 |
| Mozzanart Limited | Wholesale & retail | 2023 |
| MPH Services M/Cr Ltd | Construction | 2020 |
| Mpman Ltd | Real estate | 2018 |
| MR Captain MCR Limited | Wholesale & retail | 2024 |
| MR Worldwide Financial Services Ltd | Professional & scientific | 2025 |
| MRA Projects Limited | Professional & scientific | 2001 |
| MRM Civil Engineering Limited | Construction | 2006 |
| MRM Sharif Ltd | Real estate | 2022 |