| M-Power Enterprises Ltd | Professional & scientific | 2015 |
| M. R. & S. Enterprises Ltd | Real estate | 2023 |
| M.A. Hart Asphalt & Macadam Limited | Construction | 2000 |
| M.A. Horne Limited | Manufacturing | 1985 |
| M.B.Aufogul Ltd | Health & social care | 2018 |
| M.E.L Roofline & Flat Roofing Ltd | Construction | 2025 |
| M.G. Racing Limited | Arts & recreation | 2002 |
| M.H.A Associates Ltd | Information & communication | 2026 |
| M.M. Investment Associates Limited | | 1982 |
| M.O. Crafts Ltd | Construction | 2016 |
| M.Pugh CAD Draughting Services Limited | Information & communication | 2017 |
| M/O Entertainment Limited | Other services | 2023 |
| M2 Networks Ltd | Information & communication | 2012 |
| M7 Enterprises Ltd | Professional & scientific | 2021 |
| M87 Holdings Ltd | Financial services | 2024 |
| MA Properties (Bmth) Ltd | Construction | 2024 |
| MAB (South West) Ltd | Financial services | 2011 |
| MAC Automotive Ltd | Manufacturing | 2025 |
| Mace Joinery Limited | Construction | 2012 |
| Mace Mechanical Ltd | Construction | 2019 |
| Macemade Acquisitions Limited | Hospitality | 2024 |
| Macemade Limited | Administrative & support | 1997 |
| Macgregor Engineering Service Ltd | Mining & quarrying | 2018 |
| Macgribi Limited | Wholesale & retail | 2020 |
| MACH86 Consulting Limited | Professional & scientific | 2019 |
| Macie and DAD Property Consultants Limited | Real estate | 2019 |
| Macit Properties Limited | Real estate | 2023 |
| Mackenzie Construction (Bournemouth) Limited | Construction | 2012 |
| Mackenzie`S Freeholds Limited | Extraterritorial | 2005 |
| Macro Algotech Ltd | Financial services | 2021 |
| Macsolve Ltd | Information & communication | 2010 |
| Macting Creative Ltd | Information & communication | 2012 |
| Macwest Gardening & Landscapes Limited | Administrative & support | 2023 |
| MAD Hatter Afternoon Tea BUS Ltd | Transport & logistics | 2025 |
| MAD MAS Ltd | Manufacturing | 2019 |
| Madaict Limited | Information & communication | 2025 |
| Made and Known Ltd. | Wholesale & retail | 2020 |
| Made Apparel Ltd | Wholesale & retail | 2026 |
| Made by Katie Green Ltd | Arts & recreation | 2013 |
| Made Design Limited | Information & communication | 2002 |
| Made to Measure Productions Ltd | Arts & recreation | 2018 |
| Madina BH Ltd | Wholesale & retail | 2024 |
| Madlove Limited | Arts & recreation | 2019 |
| Mady M&C Ltd | Wholesale & retail | 2022 |
| Maestro Holdings Ltd | Financial services | 2025 |
| Magenta Group Ltd | Wholesale & retail | 2019 |
| Magerit Limited | Real estate | 2024 |
| Magic Box Home Improvements Ltd | Construction | 2022 |
| Magic Digits Ltd | Professional & scientific | 2021 |
| Magic Duck Ltd | Hospitality | 2015 |
| Magic Guys Limited | Wholesale & retail | 2021 |
| Magical Weddings (Dorset) Ltd | Other services | 2023 |
| Magicboxmedia Ltd | Professional & scientific | 2007 |
| Magiccart UK Ltd | Wholesale & retail | 2025 |
| Magna Park Self Store Ltd | Transport & logistics | 2026 |
| Magno Investments Ltd | Real estate | 2025 |
| Magnolia Accounting Ltd | Professional & scientific | 2014 |
| Magnolia Court (BH23) RTM Company Ltd | Households | 2019 |
| Magnolia Court (Bournemouth) Limited | Households | 2003 |
| Magnolia Court (Broadstone) Limited | Real estate | 2006 |
| Mahakali Properties Limited | Real estate | 2024 |
| Mahanandi Limited | Information & communication | 2022 |
| Mahler Systems Limited | Administrative & support | 1993 |
| Maia Living Ltd | Real estate | 2025 |
| Maia Management Company (Poole) Limited | Households | 2023 |
| Maid & Co Cleaning Ltd | Administrative & support | 2025 |
| Mainline Build Ltd | Construction | 2025 |
| Maison Maids Limited | Administrative & support | 2025 |
| Maison Neuve Limited | Professional & scientific | 2018 |
| Majd Intl. Co. Ltd | Education | 2023 |
| Makburga Limited | Manufacturing | 2025 |
| Make (UK) Limited | Information & communication | 2008 |
| Make Associates Ltd | Professional & scientific | 2018 |
| Makeamplify Ltd | Arts & recreation | 2016 |
| Making YOU More Limited | Professional & scientific | 2020 |
| Maksman Ltd | Transport & logistics | 2025 |
| Maksyshine Car Valeting Limited | Administrative & support | 2025 |
| Malaika Bookkeeping Ltd | Professional & scientific | 2022 |
| Malbury Properties Holdings Limited | Financial services | 2015 |
| Malbury Properties Limited | Construction | 1964 |
| Malcpd Education Consultancy & Coaching Ltd | Education | 2017 |
| Malek Property Services Ltd | Real estate | 2024 |
| Malgorzata Krimi Ltd | Professional & scientific | 2021 |
| Malgorzata Kubik Ltd | Education | 2023 |
| Malik 23 Ltd | Other services | 2024 |
| Malik AB Limited | Hospitality | 2019 |
| Malins Holdings Limited | Financial services | 2021 |
| Mallarta Painting Company (Christchurch) Limited | | 1977 |
| Mallin Group Ltd | Arts & recreation | 2026 |
| Mallorca Digital Media Ltd | Information & communication | 2017 |
| Malmesbury Park RTM Company Limited | Households | 2025 |
| Malone and Company Caterers Limited | Hospitality | 2016 |
| Malt Scrap Metal Collection Ltd | Water & waste | 2021 |
| Malu Marine Ltd | Manufacturing | 2022 |
| Malvern Court (Bournemouth) RTM Company Limited | Households | 2018 |
| Malvern Garage Ltd | Wholesale & retail | 2008 |
| Mama Bear Properties Limited | Real estate | 2025 |
| Mamai Limited | Manufacturing | 2026 |
| Mambunakunda and SON Ltd | Wholesale & retail | 2026 |
| Mamimosa Ltd | Wholesale & retail | 2025 |