| Michla Limited | Information & communication | 2010 |
| Midcam Engineering Limited | Manufacturing | 2000 |
| Middlesbrough Grange Care Home Limited | Health & social care | 2022 |
| Midway Detailing Ltd | Administrative & support | 2025 |
| Milanos Hairdresser Ltd | Other services | 2025 |
| Mill Road Catering Services Ltd | Hospitality | 2017 |
| Millmans (Butchers) Limited | Real estate | 1952 |
| Mimaai Ltd | Wholesale & retail | 2021 |
| Mims Wholesale Ltd | Water & waste | 2024 |
| Mind&Scalp Ltd | Other services | 2026 |
| Mini Gym Tots Limited | Arts & recreation | 2018 |
| Minimalist Minds Ltd | Financial services | 2024 |
| Minister Beds Ltd | Manufacturing | 2018 |
| Minnie’S Ltd | Other services | 2025 |
| MIR UK Properties Limited | Real estate | 2025 |
| MIT Holdings Limited | Construction | 2023 |
| Mitcham & Brixtons Limited | Other services | 2025 |
| MJ Developments (Ashton) Ltd | Real estate | 2016 |
| MJA Property Ltd | Real estate | 2025 |
| Mjfv Ltd | Hospitality | 2010 |
| MK Bedcraft Ltd | Manufacturing | 2025 |
| MK Everly Limited | Wholesale & retail | 2026 |
| MK Powder Coating Limited | Manufacturing | 2009 |
| MK Trade Point Ltd | Transport & logistics | 2024 |
| MK Unity Ltd | Wholesale & retail | 2025 |
| MK Waste Carriers Ltd | Water & waste | 2026 |
| MKB Logistics Ltd | Other services | 2015 |
| MKH Furniture Ltd | Manufacturing | 2016 |
| ML Locum Ltd | Health & social care | 2022 |
| MM Heating Limited | Construction | 2026 |
| Mmcs National Ltd | Education | 2022 |
| MMK Living Ltd | Wholesale & retail | 2017 |
| MN Sofa Ltd | Wholesale & retail | 2025 |
| Mobility Beds Ltd | Wholesale & retail | 2026 |
| Mocare Support Ltd | Health & social care | 2026 |
| Moda & Soak Ltd | Wholesale & retail | 2018 |
| Modafit Ltd | Wholesale & retail | 2023 |
| Modern & Luxury Ltd | Wholesale & retail | 2023 |
| Mogulhq Limited | Wholesale & retail | 2019 |
| Mohid Retail Ltd | Wholesale & retail | 2026 |
| Momentswithprecious Ltd | Information & communication | 2025 |
| Mono Beds Ltd | Manufacturing | 2025 |
| Moodi Taxi Limited | Transport & logistics | 2023 |
| Moon Rice Ltd | Hospitality | 2026 |
| Mooney Logistics Ltd | Transport & logistics | 2023 |
| Moor END Developments Limited | Construction | 2026 |
| Moorland Toolmaking Company (Holdings) Limited | Professional & scientific | 2010 |
| Moorland Toolmaking Company Limited | Manufacturing | 1985 |
| Morph Property Management Ltd | Real estate | 2018 |
| Mortgages @ Local Properties LLP | | 2005 |
| Morton & Brocktons Ltd | Wholesale & retail | 2015 |
| Mother Hubbard's Collections UK Ltd | Administrative & support | 2025 |
| Motiondrive Ltd | Professional & scientific | 2025 |
| Motorsport and Performance Limited | Wholesale & retail | 2017 |
| Motortastic Motorgroup Ltd | Wholesale & retail | 2025 |
| Mount Components Ltd | Wholesale & retail | 2020 |
| Mount Plastics Limited | Wholesale & retail | 2009 |
| Mount Property Investments Limited | Real estate | 2015 |
| Movemen Ltd | Wholesale & retail | 2023 |
| Mpas Cars Ltd | Administrative & support | 2024 |
| MPC Powder Coatings Ltd | Manufacturing | 2018 |
| Mptma Limited | Wholesale & retail | 2025 |
| MR Ceramics (UK) Ltd | Wholesale & retail | 2021 |
| MR Tee's Icecream and Desserts Ltd | Wholesale & retail | 2025 |
| MR Unknown Ltd | Wholesale & retail | 2026 |
| MRS B'S Nursery Birkenshaw Ltd | Health & social care | 2026 |
| MRS B'S Nursery Ltd | Health & social care | 2023 |
| MRS Bouquets Floristry & Event Styling Ltd | Wholesale & retail | 2018 |
| MS Automotive Solutions Ltd. | Wholesale & retail | 2023 |
| MS Optical Ltd | Health & social care | 2017 |
| MS Pharms Ltd | Health & social care | 2011 |
| MSD Capital Ltd | Real estate | 2025 |
| Msmat Limited | Other services | 2025 |
| MST Nexus Ltd | Other services | 2022 |
| MT Cooling Limited | Manufacturing | 2024 |
| Mtrs Group Ltd | Wholesale & retail | 2023 |
| MUH Properties Ltd | Real estate | 2023 |
| Muhammad Ravat Solutions Ltd | Financial services | 2025 |
| Mulinv Ltd | Real estate | 2023 |
| Mullaco (Yorkshire) Ltd | Wholesale & retail | 2018 |
| Mullaco Commercial Estates Ltd | Real estate | 2020 |
| Multichannel Ecommerce Ltd | Information & communication | 2025 |
| Murad ALI Limited | Other services | 2012 |
| Murphey Beds Limited | Manufacturing | 2023 |
| Murree Travel Limited | Wholesale & retail | 2025 |
| Mustafa Care Ltd | Health & social care | 2024 |
| Muzamil Brothers Ltd | Wholesale & retail | 2025 |
| Muzmind PVT Ltd | Information & communication | 2021 |
| Mxci (GV) Ltd | Wholesale & retail | 2018 |
| My Mortgage Advisor Ltd | Financial services | 2017 |
| My Shinwari Ltd | Hospitality | 2023 |
| MYD Finance Limited | Financial services | 2017 |
| Myer Adams (UK) Ltd | Manufacturing | 2014 |
| Mysa Beds Limited | Manufacturing | 2025 |
| Myza Property Ltd | Households | 2024 |
| MZ Corporation Ltd | Wholesale & retail | 2023 |
| MZ Tuition Ltd | Education | 2025 |
| N & G Mast Hire Limited | Administrative & support | 1997 |
| N&B Enterprise Restaurant Ltd | Hospitality | 2026 |
| N&P C2 Limited | Extraterritorial | 2009 |