| Martini Marine Limited | Manufacturing | 2026 |
| Martock Business Park Ltd | Real estate | 2024 |
| Marts for U Limited | Wholesale & retail | 2025 |
| Maruti Construction Ltd | Construction | 2025 |
| Marutiitransport Ltd | Transport & logistics | 2025 |
| Marvell Construction Ltd | Construction | 2024 |
| Marvin Architectural (U.K.) Limited | Construction | 1999 |
| Marwa Solutions Ltd | Information & communication | 2019 |
| Maryam Fruit & VEG Ltd | Wholesale & retail | 2019 |
| Masala Creations & Events Limited | Hospitality | 2023 |
| Mashallah Meat Cash and Carry Ltd | Other services | 2023 |
| Mashe Beauty Limited | Wholesale & retail | 2023 |
| Mashventures Ltd | Wholesale & retail | 2024 |
| Masif Eco Ltd | Wholesale & retail | 2026 |
| Mason & Holmes Ltd | Real estate | 2025 |
| Mason Drylining Ltd | Construction | 2025 |
| Master Joinery & Woodworks Ltd | Other services | 2020 |
| Master Wealth Network Ltd | Administrative & support | 2022 |
| Masterguild Limited | Construction | 2003 |
| Mata Construct Limited | Construction | 2019 |
| Mata Express Plumbing Limited | Construction | 2014 |
| Mata Properties Ltd | Real estate | 2020 |
| Matan Food Safety & Pest Control Ltd | Administrative & support | 2020 |
| Matharu Empire Limited | Wholesale & retail | 2026 |
| Mathiyan Transport Ltd | Transport & logistics | 2020 |
| Mathura Limited | Transport & logistics | 2018 |
| Matinée Productions Ltd | Information & communication | 2024 |
| Matish Ltd | Real estate | 2021 |
| Matrix Management Consultants Limited | Professional & scientific | 2014 |
| Matrix MOT Limited | Wholesale & retail | 2024 |
| Matrix Recovery Limited | Extraterritorial | 2024 |
| Matrix Tiles Ltd | Wholesale & retail | 2018 |
| Matta Properties Ltd | Real estate | 2022 |
| Mattu and Bhatti Painter Ltd | Construction | 2026 |
| MAUHOS123 Limited | Health & social care | 2014 |
| Maur Mansa Transport Ltd | Transport & logistics | 2026 |
| Maven Traders Ltd | Wholesale & retail | 2019 |
| MAX Capital Ltd | Professional & scientific | 2017 |
| MAX Haulage Ltd | Extraterritorial | 2018 |
| MAX Images Ltd | Professional & scientific | 2020 |
| MAX Mortgages Ltd | Financial services | 2017 |
| MAX Real Estates Ltd | Real estate | 2019 |
| Max-Gear Sports Limited | Wholesale & retail | 2020 |
| Maxdud Ltd | Wholesale & retail | 2022 |
| Maxglow (Hayes) Limited | Construction | 1982 |
| Maxroofing Ltd | Construction | 2025 |
| Maya Electric Ltd | Manufacturing | 2026 |
| Maya's Motors Ltd | Wholesale & retail | 2024 |
| Maye Services Ltd | Construction | 2022 |
| Mayfair Premium Chauffeur Limited | Transport & logistics | 2026 |
| Mayfair Street UK Ltd | Wholesale & retail | 2024 |
| Mayk.Sandhu's Ltd | Real estate | 2026 |
| Mayra Accountants Ltd | Professional & scientific | 2023 |
| Mayra Properties Management Limited | Real estate | 2025 |
| Maytree Elite Properties Ltd | Real estate | 2025 |
| MAZ Hotel Group Limited | Hospitality | 2025 |
| MAZ Traders London Ltd | Transport & logistics | 2023 |
| MB Desserts London Ltd | Hospitality | 2024 |
| MB Global Enterprise Ltd | Other services | 2015 |
| MB Link Ltd | Transport & logistics | 2025 |
| MB2024 Ltd | Wholesale & retail | 2024 |
| MBC Medical Limited | Administrative & support | 2014 |
| MBD Estates Ltd | Real estate | 2024 |
| MBI Estate Group Ltd | Real estate | 2022 |
| Mbil Properties Ltd | Real estate | 2025 |
| Mbjs Developers Ltd | Real estate | 2025 |
| MBK Homes Ltd | Real estate | 2015 |
| MBK International Ltd | Wholesale & retail | 2024 |
| MBK Properties Limited | Real estate | 2011 |
| MBS Health & Pain Relief Centre Limited | Health & social care | 2013 |
| MC Prime London Limited | Professional & scientific | 2025 |
| MCA Chauffeur Services Limited | Transport & logistics | 2016 |
| Mcattoh Ltd | Information & communication | 2019 |
| Mccann Construction Services Ltd | Construction | 2025 |
| Mclaren Residential Developments Ltd | Construction | 2018 |
| Mclaughlin & SON Build Ltd | Construction | 2019 |
| Mclean Family Group Ltd | Wholesale & retail | 2024 |
| MCM Associate Services Ltd | Administrative & support | 2022 |
| Mcmb Construction Ltd | Construction | 2019 |
| Mctan Ltd | Health & social care | 2012 |
| MD Mays Lane Ltd | Real estate | 2025 |
| MD Trade Ltd | Transport & logistics | 2017 |
| Mdent Enterprises Ltd | Health & social care | 2024 |
| MDP Property Maintenance Limited | Construction | 2021 |
| ME10 Investments Swindon Ltd | Real estate | 2026 |
| Mead Building Services Limited | Construction | 1988 |
| Meadow Waye Homes Ltd | Real estate | 2023 |
| Meadows Healthcare Service Ltd | Health & social care | 2018 |
| Meat for YOU Ltd | Wholesale & retail | 2023 |
| Medgill Ltd | Wholesale & retail | 2018 |
| Medic Cover Ltd | Administrative & support | 2023 |
| Medicare Global Health Ltd | Administrative & support | 2023 |
| Medicare Personnel Ltd | Professional & scientific | 2015 |
| Medipulse Limited | Health & social care | 2017 |
| Mediversity Global Limited | Education | 2024 |
| Medix Heating & Plumbing Ltd | Professional & scientific | 2022 |
| Medley Touch Domiciliary Care Ltd | Health & social care | 2025 |
| Meenu Kitchen Limited | Construction | 2025 |
| Meera Films Ltd | Information & communication | 2023 |
| Meezab Travel & Tours Limited | Administrative & support | 2023 |