| Mirage Upvc Limited | Construction | 2020 |
| Mirchiz Restaurant & Take Away Ltd | Hospitality | 2018 |
| Mirzaali Consulting Ltd | Construction | 2026 |
| Mirzaali Properties Ltd | Real estate | 2024 |
| Miss Carter Aesthetics Limited | Other services | 2022 |
| Missing Peace Wellbeing + Support Community Interest Company | Health & social care | 2021 |
| Mitchell's Design & Bespoke Joinery Manufacturers Ltd | Manufacturing | 2019 |
| Mitchell.M Solutions Ltd | Wholesale & retail | 2025 |
| Mitchells Transport Services Ltd | Transport & logistics | 2018 |
| Mitt Products Limited | Manufacturing | 2017 |
| MIX BF Ltd | Wholesale & retail | 2024 |
| MJ & SK Developments Ltd | Real estate | 2024 |
| MJ Pearson Properties Limited | Real estate | 2019 |
| Mj's Cash N Carry Ltd | Wholesale & retail | 2025 |
| MJC Building Solutions Ltd | Construction | 2023 |
| MJH Consult Ltd | Construction | 2022 |
| Mjshabir Ltd | Transport & logistics | 2026 |
| Mkng Ltd | Professional & scientific | 2023 |
| Mkrcad Ltd | Professional & scientific | 2019 |
| MLW Tax & Advisory Services Ltd | Professional & scientific | 2020 |
| MM Construction Contractors (Yorkshire) Ltd | Construction | 2018 |
| MMJ Seamless Gutters & Roofing Ltd | Construction | 2020 |
| MMJ Security Limited | Administrative & support | 2018 |
| Mmmatcha Ltd | Hospitality | 2026 |
| MN Consulting Services Ltd | Information & communication | 2026 |
| MNS Healthcare Ltd | Health & social care | 2024 |
| MO & L Properties Ltd | Real estate | 2026 |
| Moali Ltd | Financial services | 2026 |
| Mobeen Alam Limited | Wholesale & retail | 2010 |
| Mobonic Limited | Wholesale & retail | 2017 |
| Moda Kouture Ltd | Manufacturing | 2024 |
| Modern Delivery Solutions Limited | Transport & logistics | 2026 |
| Modern Equipment & Foundry Engineering Limited | Manufacturing | 1961 |
| Modern Garden Rooms Ltd | Manufacturing | 2015 |
| Moderna Limited | Real estate | 2006 |
| Modo Creative Limited | Arts & recreation | 2011 |
| Modoandco Limited | Wholesale & retail | 2022 |
| Modocodo Ltd | Information & communication | 2021 |
| MOG Canalside PUB Company Limited | Hospitality | 2019 |
| Mohammed PUR Welfare Trust | Education | 2013 |
| Moletech Engineering Services Limited | Manufacturing | 2018 |
| Molloy Capital Limited | Financial services | 2025 |
| Molloy Group (Holdings) Limited | Financial services | 2025 |
| Molloy Property Investments Limited | Real estate | 2025 |
| Molton Construction Company Limited | Households | 1970 |
| Mona Beauty Bar Limited | Other services | 2020 |
| Mono Verde Limited | Wholesale & retail | 2016 |
| Monok Security & Training Ltd | Financial services | 2026 |
| Monolith Build Limited | Construction | 2020 |
| Monroe Avenue Limited | Professional & scientific | 2010 |
| MONROE42 Ltd | Professional & scientific | 2023 |
| Mont Ventoux Bifolds and Conservatories Ltd. | Construction | 2015 |
| Montpelier Housing Ltd | Real estate | 2026 |
| Moomalade Ltd | Information & communication | 2013 |
| Moon Mini Market Limited | Wholesale & retail | 2025 |
| Moonbee Studios Ltd | Information & communication | 2015 |
| Moor Lane Estates Limited | Households | 2012 |
| Moore Lubricants Holdings Ltd | Wholesale & retail | 2025 |
| Moore Quantity Surveying Limited | Administrative & support | 2024 |
| Moorend Investments Limited | Administrative & support | 1973 |
| Moorend Properties Limited | Real estate | 1985 |
| Moorfield Associates Ltd | Wholesale & retail | 2018 |
| Moorhelp Personal Assistance Ltd | Health & social care | 2024 |
| Moorlands Farm (Yorkshire) Management Company Limited | Households | 2020 |
| Moorlaw Limited | Professional & scientific | 2013 |
| Moov Creative Limited | Professional & scientific | 2025 |
| Morcafe Ltd | Hospitality | 2025 |
| Morenoas Ltd | Wholesale & retail | 2025 |
| Morgreen Joinery & Roofing Ltd | Construction | 2025 |
| Moriarty Financial Limited | Professional & scientific | 2018 |
| Mornington Marine Limited | Professional & scientific | 2001 |
| Mortimer Site Services Limited | Manufacturing | 2002 |
| Morton Residents Management Company Limited | Real estate | 2007 |
| Moses Brothers Contractors Ltd | Other services | 2017 |
| Moss & Mist Woodland Experiences Ltd | Other services | 2025 |
| Moteb Global Limited | Wholesale & retail | 2026 |
| Motion Escalator Services Limited | Manufacturing | 2007 |
| Motorsure Limited | Wholesale & retail | 2007 |
| Motus Parts Ltd | Wholesale & retail | 2019 |
| Mount Compliance Ltd | Construction | 2025 |
| Mountwest Properties Ltd | Real estate | 2005 |
| MOVE2CHANGE C.I.C. | Arts & recreation | 2021 |
| MR Blue 51 Ltd | Wholesale & retail | 2025 |
| MR M'S Keighley Ltd | Hospitality | 2025 |
| MR T MAK & SI Ltd | Public administration | 2025 |
| MRG Agriplant Limited | Construction | 2019 |
| MRH Builders (UK) Ltd | Construction | 2013 |
| MRH Digital Design Limited | Professional & scientific | 2023 |
| MRS Beightons Confectionery Ltd | Wholesale & retail | 2024 |
| MRW Consultants Limited | Professional & scientific | 2005 |
| MS Capital Holdings Ltd | Wholesale & retail | 2018 |
| MS Global Holdings Limited | Real estate | 2020 |
| MS Properties Leeds Limited | Real estate | 2022 |
| MSA Optical Services Ltd | Health & social care | 2019 |
| MSA Supported Living Ltd | Health & social care | 2023 |
| MSE Pest Control Ltd | Administrative & support | 2022 |
| MSJ Consulting Services Ltd | Professional & scientific | 2023 |
| MSJ Property and Developments Ltd | Real estate | 2026 |
| Msjr Holdings Limited | Financial services | 2019 |
| MSR Developments Ltd | Construction | 2004 |