| M. Horsburgh Plumbing and Heating Services Ltd. | Construction | 2009 |
| M.E.L Developments Limited | Financial services | 2025 |
| MA Car Wash Ltd | Administrative & support | 2024 |
| MAC Cleaning Solutions Ltd | Administrative & support | 2019 |
| MAC Taxis Ltd. | Professional & scientific | 2003 |
| Macdonald Edinburgh Electrical Solar Ltd | Construction | 2022 |
| Machine Tool Technical Services Ltd | Manufacturing | 2003 |
| Mack & Laidlaw Builders Ltd | Construction | 2026 |
| Mackay and Lynn Limited | Wholesale & retail | 1969 |
| Mackay&Co Real Estate Limited | Real estate | 2025 |
| Maclin Electric Limited | Construction | 1977 |
| Macroofing & Building Limited | Construction | 2015 |
| Maeve Wellness Ltd | Other services | 2024 |
| Mafdevelopments Ltd | Construction | 2023 |
| Makocon Events Ltd | Arts & recreation | 2025 |
| Makwan Company Limited | Hospitality | 2024 |
| Malcolm Fallas Heating Ltd | Construction | 2018 |
| Mamona Ltd | Information & communication | 2021 |
| Manheath & Mcnair | | 1981 |
| Manor Place Films Ltd | Information & communication | 2023 |
| Maple Leaf Joinery Ltd. | Construction | 2003 |
| Martin Cook Accounting Services Ltd. | Professional & scientific | 2009 |
| Martinesz & Webb Ltd | Construction | 2025 |
| Marzena D'Arcy Ltd | Professional & scientific | 2024 |
| Mason Cost Management Limited | Administrative & support | 2008 |
| Matgrad Ltd. | Professional & scientific | 1999 |
| Maverick Properties (Musselburgh) Limited | Real estate | 2018 |
| Maxcess Scaffolding Limited | Construction | 1981 |
| Maxim Sports Ltd | Arts & recreation | 2025 |
| MB (Edin) Ltd | Wholesale & retail | 2017 |
| MB Joinery EDI Ltd | Construction | 2023 |
| MB Medico-Legal Limited | Health & social care | 2020 |
| MCD Homes Limited | Construction | 2022 |
| Mchaney LLP | | 2020 |
| Mckenzie (Scotland) Ltd | Professional & scientific | 2006 |
| Mckenzie (Secretarial Services) Ltd | Administrative & support | 2014 |
| Mckeown Investment Property Ltd | Real estate | 2021 |
| Mckerracher Consulting Ltd | Professional & scientific | 2015 |
| Mcpherson Day Ltd | Wholesale & retail | 2018 |
| MEB Ognamy Ltd | Education | 2018 |
| Mehar&Co Ltd | Real estate | 2024 |
| Mellow Software Limited | Information & communication | 2019 |
| Mellow Studio Limited | Information & communication | 2010 |
| Mercat Grill Trading Company Limited | Hospitality | 2014 |
| Mercat Takeaways Limited | Hospitality | 2025 |
| Meridian Intelligence Systems Ltd | Administrative & support | 2026 |
| Metasta Ltd | Professional & scientific | 2023 |
| Meze Meze Ltd | Hospitality | 2014 |
| MG Edinburgh Ltd | Administrative & support | 2019 |
| Midlothian and East Lothian Chamber of Commerce | Administrative & support | 1997 |
| Mikas Design Ltd | Manufacturing | 2020 |
| Miller Mitchell Media Limited | Information & communication | 2016 |
| Millersoft Limited | Information & communication | 1996 |
| Mint Chinese Film Festival Scotland CIC | Information & communication | 2025 |
| Miros Harbour Limited | Hospitality | 2026 |
| Miros Musselburgh Ltd | Hospitality | 2023 |
| MJG Specialist Services Ltd | Professional & scientific | 2019 |
| MLR Technical Ltd | Construction | 2024 |
| MM Digital Finance Ltd | Professional & scientific | 2026 |
| Mmbr Limited | Hospitality | 2026 |
| MNR6 Ltd | Arts & recreation | 2020 |
| Moffat Logistics Ltd | Transport & logistics | 2021 |
| Moffat Property Investments Ltd | Real estate | 2025 |
| Momentum V1 Ltd | Hospitality | 2019 |
| Momentumnrg Fitness Online Ltd | Health & social care | 2021 |
| Montgomery Virtual Solutions Limited | Administrative & support | 2018 |
| Moredun Park Development Ltd | Construction | 2021 |
| Movement Remedies Ltd | Arts & recreation | 2024 |
| MP Windows Direct Ltd | Construction | 2022 |
| MPA001 Ltd | Hospitality | 2026 |
| MR Musa Barber Scissors Ltd | Other services | 2021 |
| MRB Maintenance Ltd | Construction | 2020 |
| MRM Scaffolding Ltd | Construction | 2024 |
| MUG Shots Ltd | Manufacturing | 2026 |
| Muirfield Construction Ltd | Construction | 2023 |
| Muirfield Property Ltd | Real estate | 2024 |
| Murrayfield Hair & Beauty Ltd | Other services | 2024 |
| Muski Ltd | Real estate | 2025 |
| Musselburgh Athletic FC CIC | Arts & recreation | 2025 |
| Musselburgh Barber Ltd | Other services | 2022 |
| Musselburgh Business Partnership Limited | Other services | 2018 |
| Musselburgh Electrics Limited | Construction | 2008 |
| Musselburgh Express Shop Ltd | Wholesale & retail | 2025 |
| Musselburgh Express Store Ltd | Wholesale & retail | 2026 |
| Musselburgh Golf Services Ltd | Wholesale & retail | 2013 |
| Musselburgh Maintenance Company Limited | Construction | 2023 |
| Musselburgh Martial Arts Ltd | Education | 2024 |
| Musselburgh News Ltd | Wholesale & retail | 2021 |
| Musselburgh Picture Framers Ltd | Manufacturing | 2023 |
| Musselburgh Private Nursery Ltd | Education | 2008 |
| Musselburgh Slaters Limited | Construction | 2020 |
| Musselburgh Wagon Company Limited | Manufacturing | 1956 |
| Mustafa Stores 2 Limited | Wholesale & retail | 2026 |
| Muthyal Ltd | Construction | 2025 |
| N-Reth Enterprise Limited | Wholesale & retail | 2025 |
| Naka Media LLP | | 2020 |
| NAL Wallace Travel Ltd | Administrative & support | 2020 |
| Nats Taxis Ltd. | Professional & scientific | 1999 |
| NB CLEAN2PERFECTION Ltd | Administrative & support | 2022 |
| NB Garage Ltd | Wholesale & retail | 2021 |