| Michaels Cafe Ltd | Hospitality | 2023 |
| Mickc Ltd | Construction | 2024 |
| Micks Kitchen NE Ltd | Hospitality | 2023 |
| Milad KH Ltd | Professional & scientific | 2018 |
| Milburn Direct Services Limited | Other services | 2017 |
| Millar Fire Safety Consultants Ltd | Professional & scientific | 2019 |
| Millennium Asset Group Ltd | Real estate | 2026 |
| Mills Efficient Energy Group Limited | Construction | 2025 |
| Milo & Co NE Ltd | Real estate | 2021 |
| Milotransport Limited | Transport & logistics | 2016 |
| Minchella Properties Limited | Real estate | 2022 |
| Minchella's Ice Cream Limited | Manufacturing | 2023 |
| Mindset Warriors Kidz Ltd | Arts & recreation | 2024 |
| Mindset Warriors Ltd | Arts & recreation | 2024 |
| Mine Market Express Ltd | Wholesale & retail | 2025 |
| Mini Drip Ltd | Wholesale & retail | 2025 |
| Mini Market South Shields Ltd | Wholesale & retail | 2025 |
| Minismart Limited | Wholesale & retail | 2022 |
| Minted Ltd | Construction | 2022 |
| Mishti Mukh Productions Ltd | Manufacturing | 2026 |
| Misk Cosmetics Ltd | Wholesale & retail | 2026 |
| Mivesi Event Catering and Spices Ltd | Hospitality | 2018 |
| MJF Financial Services Limited | Financial services | 2010 |
| MJS Access Limited | Professional & scientific | 2019 |
| MK Waste Management Ltd | Water & waste | 2025 |
| MKU Pharmc Ltd | Health & social care | 2021 |
| MLA Electrics Ltd | Energy | 2025 |
| MLI Consulting Limited | Information & communication | 2014 |
| MLR Consulting Engineers Limited | Professional & scientific | 2021 |
| MM Tyneside Ltd | Administrative & support | 2019 |
| Mmea (UK) Ltd. | Wholesale & retail | 2014 |
| MMK Management Consultancy Ltd | Professional & scientific | 2011 |
| MMS Residential Limited | Real estate | 2024 |
| MNX Security Limited | Administrative & support | 2003 |
| MO' Incorporation Limited | Other services | 2024 |
| Mobile Car Spa Franchising Ltd | Wholesale & retail | 2015 |
| Mobile Car Spa Ltd | Wholesale & retail | 2014 |
| Mobile Industrial Maintenance Limited | Professional & scientific | 1982 |
| Mobile Phones and Repair Centre Ltd | Wholesale & retail | 2026 |
| Mobilevetz Limited | Other services | 2007 |
| Modjule Limited | Wholesale & retail | 2017 |
| Molten Mouse Ltd | Administrative & support | 2016 |
| Money Logic Technologies Ltd | Information & communication | 2025 |
| Monkton Academy | Education | 2012 |
| Monkton Gardens (Hebburn) Management Company Limited | Households | 2023 |
| Monkton Infants School | Education | 2013 |
| Monta Musica Ltd | Information & communication | 2014 |
| Monument Developments NE Ltd | Construction | 2023 |
| Moorcroft Metal Fabrications Limited | Manufacturing | 2009 |
| Moorhill Court Limited | Professional & scientific | 2003 |
| More Checkouts Ltd | Information & communication | 2024 |
| Morfose Cramlington Limited | Other services | 2022 |
| Morfose Furniture & Fitting Limited | Manufacturing | 2017 |
| Morfose Galleries Limited | Other services | 2015 |
| Morfose Longbenton Limited | Hospitality | 2023 |
| Morfose Properties Limited | Households | 2024 |
| Morgan Green Limited | Real estate | 2023 |
| Mort Property Investments Ltd | Real estate | 2021 |
| Mortimer Builders Limited | Construction | 2025 |
| Motor Vehicle Solutions North East Ltd | Wholesale & retail | 2019 |
| Motorhome Happiness Community Interest Company | Hospitality | 2022 |
| Move and Mind Limited | Arts & recreation | 2020 |
| Mowbray Ltd | Information & communication | 2021 |
| Mpks Ventures Ltd | Real estate | 2023 |
| MPW Mill DAM Limited | Hospitality | 2025 |
| MR Swainston's Ltd | Wholesale & retail | 2024 |
| MR Vape NE Limited | Wholesale & retail | 2025 |
| MR. Burger South Sheilds Limited | Hospitality | 2025 |
| MRS Northern Limited | Other services | 2024 |
| MS Beauty and Retail Ltd | Other services | 2025 |
| MS Civils & Groundworks Ltd | Construction | 2016 |
| MS Commercial Repairs Ltd | Wholesale & retail | 2009 |
| MS Horseboxes Ltd | Wholesale & retail | 2009 |
| MSA Investment Properties Limited | Real estate | 2024 |
| MSE Plumbing & Heating Limited | Construction | 2016 |
| MSW Joinery Ltd | Manufacturing | 2020 |
| Mubys Properties Ltd | Real estate | 2019 |
| Mucky Hands Garden Centre Limited | Wholesale & retail | 2020 |
| Mukcorp Private Financial Group Limited | Professional & scientific | 2025 |
| Mukcorp Renewable Technologies Group (UK) Ltd | Energy | 2025 |
| Mukcorp Retail Group Limited | Wholesale & retail | 2025 |
| Mulholland and Tiffin Limited | Households | 2019 |
| Multi Contracts Limited Limited | Construction | 2018 |
| Multiply Ventures Ltd | Professional & scientific | 2024 |
| Murder Mysteries Inc Ltd | Arts & recreation | 2021 |
| Muri Mayaki Properties Ltd | Real estate | 2020 |
| Muse Nail SS Ltd | Other services | 2024 |
| Mushworx Ltd | Wholesale & retail | 2026 |
| Mustafa ZAM ZAM South Shields Ltd | Wholesale & retail | 2019 |
| Mustard Stories Arts CIC | Arts & recreation | 2022 |
| Muti Barber Ltd | Other services | 2024 |
| MW Legionella Compliance Ltd | Professional & scientific | 2014 |
| MWB Roofing Ltd | Construction | 2026 |
| MWJ Technical Ltd | Manufacturing | 2023 |
| MWS Plumbing & Heating Limited | Administrative & support | 2010 |
| MWS Property Maintenance Limited | Other services | 2016 |
| My Aiva Ltd | Information & communication | 2025 |
| My Learning Apps Ltd | Information & communication | 2016 |
| My Track Limited | Administrative & support | 2011 |
| Myinfinity Finance Limited | Financial services | 2013 |