| Millerbeck Light Railway Ltd | Arts & recreation | 2001 |
| Millian Developments Limited | Real estate | 2025 |
| Millsgills Consulting Ltd | Professional & scientific | 2025 |
| Millwood Administration Group Ltd | Administrative & support | 2021 |
| Miloda Properties Limited | Real estate | 1958 |
| Milton Associates Limited | Financial services | 2024 |
| Milton Grill Ltd | Hospitality | 2019 |
| Mimi Belle Weddings Ltd | Professional & scientific | 2024 |
| MIN WOO NAM Studio Ltd | Arts & recreation | 2022 |
| Mindful Futures CIC | Health & social care | 2021 |
| Mindhackers Limited | Education | 2025 |
| Mingletime Limited | Real estate | 1993 |
| Minimax Tyres Limited | Wholesale & retail | 2005 |
| MIR Takeaway Limited | Hospitality | 2024 |
| Mira Property Management Ltd | Financial services | 2023 |
| Miranda Lettings Limited | Real estate | 2019 |
| Mission Wave Apartments Ltd | Real estate | 2020 |
| Mitchell Holywell Solutions Limited | Information & communication | 2026 |
| MJ Cunningham and Co Limited | Financial services | 2026 |
| Mjcarsales Ltd | Wholesale & retail | 2019 |
| MJG Fire & Security Ltd | Construction | 2022 |
| MJH Flooring Limited | Construction | 2023 |
| MJK Lowton Ltd | Health & social care | 2015 |
| MJK Surveys UK Ltd | Professional & scientific | 2013 |
| MJO Developments Limited | Real estate | 2016 |
| MJO Global Limited | Wholesale & retail | 2018 |
| MJP Flooring Limited | Construction | 2006 |
| Mjpavitt Holdings Ltd | Real estate | 2026 |
| Mjsmarketing Limited | Professional & scientific | 2019 |
| Mjvaleting Ltd | Administrative & support | 2019 |
| MK Agyapong Removals and Deliveries Ltd | Other services | 2017 |
| MK Porter Ltd | Administrative & support | 2020 |
| MK Pro Cleaning Services Ltd | Manufacturing | 2025 |
| MK Vision Homes Limited | Real estate | 2025 |
| Mkml Developments Limited | Real estate | 2006 |
| MKS Roofing Ltd | Construction | 2021 |
| MM Wine Ltd | Hospitality | 2020 |
| MM Wine Sellers Ltd | Hospitality | 2020 |
| MMP13 Ltd | Professional & scientific | 2021 |
| MMW Builders Ltd | Construction | 2025 |
| MMW Shopfitters Limited | Construction | 2016 |
| MO 1 Barber Ltd | Other services | 2026 |
| MO Healthcare Limited | Health & social care | 2016 |
| Mobarak Medical Services Ltd | Health & social care | 2024 |
| Mobile Craft 4 U Community Interest Company | Arts & recreation | 2015 |
| Mobile Millennium Limited | Wholesale & retail | 1998 |
| Mobile Resources Ltd | Other services | 2001 |
| Mocanu Hand Carwash Limited | Administrative & support | 2018 |
| Mocktails and Dreams CIC | Hospitality | 2026 |
| Mode Aesthetic Growth Consultancy Ltd | Administrative & support | 2026 |
| Modelling Electronics Ltd | Wholesale & retail | 2024 |
| Modern Business Ltd | Wholesale & retail | 2022 |
| Modo Creations Limited | Wholesale & retail | 2003 |
| Modo Products Ltd | Wholesale & retail | 2021 |
| Modular Cleaning Services Ltd | Administrative & support | 2019 |
| Modus Personnel Ltd | Administrative & support | 2021 |
| Modus RP Limited | Professional & scientific | 2016 |
| Moghul IT Consulting Ltd | Information & communication | 2013 |
| MOH Fire Alarms Limited | Manufacturing | 2019 |
| Mohamed Shami Ltd | Health & social care | 2022 |
| MOI Bistro Ltd | Hospitality | 2025 |
| Mole END Developments Limited | Real estate | 2007 |
| Molyneux Kale Company Limited | Wholesale & retail | 2013 |
| Momma's House Ltd | Wholesale & retail | 2016 |
| Monahan Travel Ltd | Transport & logistics | 2018 |
| Monarch Medical Services Ltd | Health & social care | 2021 |
| Monetta Mundas Limited | Financial services | 2025 |
| Money Money Money Limited | Hospitality | 2005 |
| Money Sphere Ltd | Financial services | 2017 |
| Monsieur Corners Ltd | Administrative & support | 2003 |
| Montagu Mews Management Company Limited | Households | 1989 |
| Montague Charles Ltd | Professional & scientific | 2017 |
| Monterey Developments Ltd | Real estate | 2016 |
| Moonlight Events Ltd | Administrative & support | 2021 |
| Moonlight PVT Limited | Hospitality | 2020 |
| Moor Court Management Company Limited | Households | 1987 |
| Moor Farm (Minety) Ltd | Agriculture & fishing | 2016 |
| Moorcroft Plastering and Rendering Limited | Construction | 2022 |
| Moorcroft Property Ltd | Real estate | 2024 |
| Moore Properties Limited | Real estate | 2004 |
| Moore Property Consulting Ltd | Administrative & support | 2023 |
| Moores Property Group UK Ltd | Real estate | 2018 |
| Moorside Medicines Management Services LLP | | 2013 |
| Moov Reformer Pilates Ltd | Arts & recreation | 2024 |
| More Property Choices Ltd | Real estate | 2024 |
| Morgan Finch Solicitors Limited | Professional & scientific | 2017 |
| Morgan Hope Holdings Ltd | Financial services | 2023 |
| Morgan Hope Industries Limited | Wholesale & retail | 1992 |
| Moricol Ltd | Education | 2019 |
| Morley Road Management Limited | Real estate | 2004 |
| Morningside (Southport) Management Company Limited | Households | 2017 |
| Mornington Road Garage Limited | Wholesale & retail | 2020 |
| Mortgage Gate Financial Services Limited | Financial services | 2021 |
| Mortgage Gate Ltd | Financial services | 2005 |
| Morval Grange Limited | Real estate | 2024 |
| Mosaic Ventures Limited | Professional & scientific | 2025 |
| Mossgiel Avenue Management Company Limited | Real estate | 1983 |
| Mosswoods BA Solutions Ltd | Administrative & support | 2015 |
| Mostload Trading Limited | Financial services | 1994 |
| Motion Group Agency Ltd | Professional & scientific | 2024 |