| Majesty Residential Services Ltd | Construction | 2018 |
| Major Money Matters Limited | Financial services | 2003 |
| Major Money Matters Property Ltd | Real estate | 2019 |
| Majoris Group Ltd | Construction | 2018 |
| MAK Interiors Limited | Construction | 2019 |
| Makanaka Limited | Transport & logistics | 2024 |
| Make a Difference at Sandies | Health & social care | 2012 |
| Make HAY Ltd | Real estate | 2019 |
| Make Ideas Limited | Education | 2017 |
| Make IT Gluten Free Limited | Hospitality | 2015 |
| MAKEWAY4GROWTH CIC | Administrative & support | 2020 |
| Making Headway Limited | Professional & scientific | 2017 |
| Making Learning Easy Ltd | Education | 2019 |
| Makkas Limited | Wholesale & retail | 2020 |
| Maknas Accountants Ltd | Professional & scientific | 2021 |
| Makola Market London Limited | Wholesale & retail | 2021 |
| Makolabsuk Ltd | Manufacturing | 2024 |
| Maks Associates Ltd | Administrative & support | 2017 |
| Maks L Ltd | Administrative & support | 2025 |
| Maks Properties Limited | Real estate | 2021 |
| Maksz Ltd | Wholesale & retail | 2020 |
| Mala at the Rodings Ltd | Hospitality | 2026 |
| Mala Body Piercing Ltd | Wholesale & retail | 2019 |
| Malachite House RTM Company Limited | Households | 2025 |
| Malakh Logistics Limited | Transport & logistics | 2026 |
| Malayali 360 Ltd | Wholesale & retail | 2026 |
| Maldives Made Easy Ltd | Administrative & support | 2024 |
| Malev Group Ltd | Other services | 2024 |
| Malex Maintenance Ltd | Construction | 2024 |
| Maliguta Construction Ltd | Construction | 2019 |
| Maliktec Limited | Wholesale & retail | 2026 |
| Malisa Lighting Limited | Construction | 1999 |
| Malk Property Investments Limited | Real estate | 2018 |
| Malleum Limited | Real estate | 2024 |
| Malplex Limited | Real estate | 2022 |
| Malvern Road Investments Ltd | Real estate | 2024 |
| Malvin & Lena Limited | Construction | 2018 |
| MAM Elect Services Ltd | Construction | 2026 |
| Mamaniiis Foods Limited | Wholesale & retail | 2025 |
| Mamatemz Events Limited | Hospitality | 2026 |
| Mami Property Ltd | Real estate | 2026 |
| Mamj Developments Limited | Real estate | 2021 |
| Mamog Limited | Health & social care | 2022 |
| Mamu and Daote Consulting Limited | Professional & scientific | 2021 |
| Manage IT Consulting Limited | Professional & scientific | 2008 |
| Manakish & Naanza Limited | Hospitality | 2021 |
| Manatee Marketing Limited | Other services | 2018 |
| Manc&Dandy Ltd | Administrative & support | 2014 |
| Manchanda & Company Limited | Other services | 2010 |
| Mandhan Transport Ltd | Transport & logistics | 2025 |
| Mandiprov Ltd | Wholesale & retail | 2024 |
| Mandylyne Limited | Wholesale & retail | 2025 |
| Manerium House Management Company Limited | Households | 2025 |
| Manga Construction Limited | Construction | 2024 |
| Mango Solutions Recruitment Group Ltd | Administrative & support | 2024 |
| Manha Medics Limited | Health & social care | 2015 |
| Manha Momtaz Properties (UK) Ltd | Real estate | 2020 |
| Manhib Limited | Construction | 2018 |
| Mani Gynae Care Limited | Health & social care | 2017 |
| Manic Merchandise Limited | Wholesale & retail | 2016 |
| Manison Group Ltd | Administrative & support | 2017 |
| Manivince Ltd | Real estate | 2025 |
| Manj Services Ltd | Hospitality | 2019 |
| Mankind Marketing Ltd | Professional & scientific | 2026 |
| Manm Enterprise Ltd | Health & social care | 2023 |
| Mann & Mann Limited | Real estate | 2005 |
| Mann Driving School Limited | Education | 2024 |
| Mann Shopfronts Limited | Construction | 2016 |
| Mann Umpleby Engineering Co. Limited | Construction | 1973 |
| Manne Software Ltd | Information & communication | 2019 |
| Mannel Investments Ltd | Extraterritorial | 2024 |
| Manoilov Drylining Expert Ltd | Construction | 2022 |
| Manor Finance LLP | | 2022 |
| Manor Green Properties Ltd | Real estate | 2022 |
| Manor Mews Property Ltd | Real estate | 2022 |
| Manor Property Sourcing Ltd | Real estate | 2026 |
| Manorstone Construction Ltd | Construction | 2025 |
| Manpower Agency Limited | Administrative & support | 2019 |
| Mansa Europe Limited | Transport & logistics | 2025 |
| Mansell Lettings Limited | Real estate | 2026 |
| Mansell Signal Sighting Limited | Professional & scientific | 2021 |
| Mansor Care Ltd | Health & social care | 2024 |
| Manston Leisure Limited | Arts & recreation | 2014 |
| Mantra Investment LDN Ltd | Real estate | 2022 |
| Manurq Global Services Limited | Real estate | 2007 |
| Manywaters Ltd | Extraterritorial | 2024 |
| Manzil Tandoori Ltd | Hospitality | 2023 |
| Mape Construction Ltd | Construction | 2025 |
| Maple Leaf Quality Care Ltd | Health & social care | 2013 |
| Mapule Private Limited | Health & social care | 2016 |
| MAQ Consultants London Ltd | Information & communication | 2026 |
| MAQ London Holdings Limited | Information & communication | 2025 |
| Maquis Payroll Services Ltd | Administrative & support | 2018 |
| MAR DEV Limited | Real estate | 2024 |
| Mar&Building Ltd | Construction | 2025 |
| Marc Pearce Financial Services Limited | Financial services | 2023 |
| Marcelo GR Euro SP Ltd | Information & communication | 2025 |
| March Flooring Limited | Construction | 2026 |
| Marcio Removal Services Ltd | Water & waste | 2025 |
| Marcone Logistics Ltd | Transport & logistics | 2014 |