| MM Health Partners Ltd | Professional & scientific | 2022 |
| MM Rigging Ltd | Construction | 2025 |
| Mm&Bb Construction Ltd | Construction | 2024 |
| MMA Fashion Ltd | Wholesale & retail | 2026 |
| Mmht Limited | Other services | 2024 |
| MMJ Utility Services Ltd | Other services | 2024 |
| MMK UK Properties Ltd | Real estate | 2023 |
| MMS Trucking Services Ltd | Transport & logistics | 2025 |
| MN Murray Ltd | Financial services | 2019 |
| MNA Pro Ltd | Construction | 2021 |
| MNG Roofing Ltd | Construction | 2022 |
| MNH Wholesale Food Limited | Wholesale & retail | 2021 |
| MNS Decorating Ltd | Construction | 2023 |
| MO and Co Properties Ltd | Real estate | 2023 |
| MOB and KO Studios Ltd | Other services | 2024 |
| Mobile World Technologies Ltd | Wholesale & retail | 2018 |
| Mobius Limited | Wholesale & retail | 2009 |
| Mobolarosa Services Ltd | Administrative & support | 2025 |
| Mochi Vibe Company Limited | Wholesale & retail | 2025 |
| Moco DX Ltd | Professional & scientific | 2020 |
| Modern Legal Limited | Professional & scientific | 2024 |
| Modern Plumbing and Heating Ltd | Construction | 2008 |
| Modern WIN Ltd | Professional & scientific | 2015 |
| Modeva London Ltd | Wholesale & retail | 2026 |
| Moditelecom Limited | Professional & scientific | 2010 |
| Modron Solutions Ltd | Information & communication | 2025 |
| Moers Group Limited | Construction | 2020 |
| Mohamed Tutors Limited | Education | 2025 |
| Moise L Ltd | Transport & logistics | 2018 |
| Mojos Woodford Limited | Hospitality | 2019 |
| Mokanju Limited | Health & social care | 2019 |
| Moleo Ltd | Wholesale & retail | 2024 |
| Molliebelle Limited | Financial services | 2017 |
| Momentum Project Management Ltd | Construction | 2025 |
| MOMENTUM24 Limited | Information & communication | 2013 |
| Momolux Ltd | Wholesale & retail | 2025 |
| Momos Consultancy Limited | Other services | 2018 |
| Moms on a Mission Global Ministries Ltd | Education | 2023 |
| MON Reve Art and Fashion Ltd | Wholesale & retail | 2025 |
| Mona Lisas Smile Ltd | Administrative & support | 2026 |
| Monde Air Ltd | Transport & logistics | 2013 |
| Mondial Forwarding (Investments) Ltd | Professional & scientific | 1974 |
| Mondial Forwarding Limited | Extraterritorial | 2024 |
| Mondihome Ltd | Wholesale & retail | 2025 |
| Mondsworth Consulting Ltd | Extraterritorial | 2013 |
| Mone Light Limited | Information & communication | 2010 |
| Moniqueskitchenomoni Ltd | Wholesale & retail | 2025 |
| Monkswood Way Ltd | Administrative & support | 2024 |
| Mono Architecture and Design Ltd | Professional & scientific | 2025 |
| Mono Holdings Limited | Professional & scientific | 1999 |
| Mono UK Limited | Manufacturing | 2006 |
| Monochrome Tech Ltd | Wholesale & retail | 2026 |
| Monolit 18 Ltd | Construction | 2023 |
| Monolith Property Management Limited | Real estate | 2016 |
| Monopetra Ltd | Construction | 2022 |
| Monopoly Property Management Ltd | Households | 2018 |
| Montclare Limited | Construction | 2012 |
| Montgomrey's Wharf LLP | | 2021 |
| Monumental Construction Ltd | Construction | 2023 |
| Moon and Brothers Limited | Wholesale & retail | 2024 |
| Moon Global Ltd | Wholesale & retail | 2024 |
| Moonchild Holistic Healing Ltd | Wholesale & retail | 2022 |
| Moonlight Care Ltd | Health & social care | 2019 |
| Moore Consultancy Limited | Professional & scientific | 2019 |
| Mooter Limited | Education | 2025 |
| Moove Removals Limited | Transport & logistics | 2026 |
| Moral Booster Limited | Construction | 2019 |
| Morchecks Healthcare Ltd | Health & social care | 2025 |
| Mordon Designs Limited | Professional & scientific | 1997 |
| More IT Solutions Limited | Information & communication | 2022 |
| More North Ltd | Professional & scientific | 2026 |
| More Than Money Empire Ltd | Wholesale & retail | 2024 |
| Moreland & Co Solicitors Limited | Professional & scientific | 2006 |
| Moreland House Investments Ltd | Real estate | 2013 |
| Moreni B Limited | Administrative & support | 2016 |
| Morepay Ltd | Financial services | 2026 |
| Morgan & More Ltd | Real estate | 2023 |
| Morgan Davies Limited | Real estate | 1998 |
| Morina London Ltd | Construction | 2024 |
| Morland Digital Limited | Information & communication | 2013 |
| Mormile Builders Ltd | Construction | 2025 |
| Morning Star Trust | Arts & recreation | 1989 |
| Morningdew Assets Limited | Real estate | 2017 |
| Morningstone Properties Limited | Real estate | 2022 |
| Morris Steve & Jacob Ltd | Professional & scientific | 2021 |
| Morris Training and Consultancy Limited | Education | 2023 |
| Morsley Services Ltd | Administrative & support | 2026 |
| Mosaique Global Ltd | Professional & scientific | 2025 |
| Mosiah Property Management Ltd | Construction | 2025 |
| Mosque Mapper Ltd | Information & communication | 2023 |
| Mostarac Barnes Consulting Limited | Professional & scientific | 2007 |
| Mota Antiques Ltd | Wholesale & retail | 2025 |
| Mota Estates Limited | Real estate | 2019 |
| Mother of Georgia Ltd | Hospitality | 2026 |
| Mother's and Kids Helpers Limited | Education | 2024 |
| MOTIV8 Educational Limited | Education | 2015 |
| Moto Car Finance Ltd | Financial services | 2022 |
| Motoclaims Ltd | Professional & scientific | 2004 |
| Motohire (UK) Ltd | Professional & scientific | 2004 |
| Motor Base Automobiles Ltd | Wholesale & retail | 2022 |