| MJM Inspection Services Ltd | Professional & scientific | 2019 |
| MJM Instruments Limited | Professional & scientific | 2020 |
| MJM Management Group Ltd | Hospitality | 2017 |
| MJM Trading NE Ltd | Wholesale & retail | 2026 |
| Mjmcommissioning Ltd | Construction | 2025 |
| Mjnc Holdings Limited | Financial services | 2021 |
| MJV Promotions Limited | Arts & recreation | 2024 |
| MJW Technical Solutions Limited | Construction | 2013 |
| MK Art Castle Ltd | Wholesale & retail | 2023 |
| MK Energy Services Ltd | Professional & scientific | 2025 |
| MK Portfolio Ltd | Real estate | 2021 |
| MK Project Controls Ltd | Professional & scientific | 2025 |
| MKB Engineering Services Ltd | Professional & scientific | 2023 |
| MKB Holdings (North East) Ltd | Financial services | 2025 |
| MKB Property North East Ltd | Construction | 2024 |
| MKB Rentals (North East) Ltd | Real estate | 2025 |
| MKD R&R Ltd | Wholesale & retail | 2025 |
| Mkjk Services Limited | Professional & scientific | 2022 |
| MKM Traders Ltd | Wholesale & retail | 2021 |
| MKO Wiharbi Ltd | Construction | 2024 |
| MKR Plumbing and Heating Ltd | Construction | 2022 |
| Mkrepairz Ltd | Wholesale & retail | 2025 |
| MKT Partnerships Ltd | Administrative & support | 2024 |
| ML Japanese Imports Ltd | Wholesale & retail | 2026 |
| ML Private Limited | Transport & logistics | 2023 |
| MLI Holdings Ltd | Financial services | 2021 |
| Mlkp Engineering Services Ltd | Professional & scientific | 2025 |
| MLM Renewspaces Ltd | Construction | 2024 |
| MLN Global Group Limited | Manufacturing | 2026 |
| MM Electrical & Joinery Ltd | Construction | 2021 |
| MM Wind Solutions Ltd | Professional & scientific | 2022 |
| Mm-Group Holdings Limited | Financial services | 2019 |
| MM1 Hand Car Wash Ltd | Administrative & support | 2025 |
| MMA Brothers 3PL Sales & Services Ltd | Other services | 2024 |
| MMB Project Management Limited | Construction | 2016 |
| Mmfk Optical Ltd | Health & social care | 2022 |
| Mmhl Limited | Hospitality | 2022 |
| Mmhmm Studio Ltd | Information & communication | 2026 |
| MMM Property Group Limited | Real estate | 2025 |
| MMP Retail Limited | Wholesale & retail | 2025 |
| MMW Holmes Ltd | Real estate | 2018 |
| MN Care Associates Ltd | Health & social care | 2025 |
| MN Property Rentals Ltd | Real estate | 2021 |
| MNB Engineering Services Limited | Professional & scientific | 2020 |
| MND Automotive Ltd | Wholesale & retail | 2025 |
| MNH Coatings Ltd | Construction | 2026 |
| MO Estates Ltd | Real estate | 2025 |
| MO Fade Lounge Ltd | Other services | 2025 |
| MO Inspection Services Ltd | Professional & scientific | 2024 |
| Mo's Barbers Ferryhill Ltd | Other services | 2025 |
| Moana Marine Ltd | Transport & logistics | 2025 |
| Mobile Paint 'N' Polish Ltd | Wholesale & retail | 2016 |
| Mobiotech Ltd | Wholesale & retail | 2026 |
| Mobix Ltd | Information & communication | 2019 |
| Moda Bellas Closet Ltd | Wholesale & retail | 2023 |
| Moda Doors Limited | Extraterritorial | 2019 |
| Mode Interiors Ltd | Professional & scientific | 2020 |
| Model.M Limited | Wholesale & retail | 2023 |
| Mody Retail & Online Supplies Ltd | Wholesale & retail | 2025 |
| Moedas Ltd | Real estate | 2026 |
| MOH Northeast Ltd | Hospitality | 2025 |
| MOH Transport 2022 Ltd | Transport & logistics | 2022 |
| Mohammad Ilyas Ltd | Real estate | 2020 |
| Mohammed Shabir Properties Ltd | Real estate | 2026 |
| Mohsin Bilal Ltd | Wholesale & retail | 2026 |
| Mohtech Holdings Ltd | Real estate | 2025 |
| Mohtech Properties Ltd | Real estate | 2025 |
| Mohtech Solutions Ltd | Information & communication | 2007 |
| Mojoe's Cuisine Ltd | Hospitality | 2025 |
| Mokgalo Limited | Real estate | 2023 |
| Mollandal Ltd | Professional & scientific | 2014 |
| Momento Stokesley Ltd | Hospitality | 2018 |
| Momentum Properties Ltd | Real estate | 2026 |
| Momentum X Ltd | Wholesale & retail | 2026 |
| Mona Homes Ltd | Real estate | 2021 |
| Moncur Reece Ltd | Professional & scientific | 2010 |
| Monde Nissin (UK) Limited | Manufacturing | 2015 |
| Monel Dessert Specialist Ltd | Hospitality | 2025 |
| Money Saving Direct (Property Valuation Services) Ltd | Other services | 2010 |
| Monilogic Innovations Ltd | Professional & scientific | 2025 |
| Mono Supplies Ltd | Wholesale & retail | 2024 |
| Monocle Maintenance Ltd | Real estate | 2026 |
| Monocle Property Ltd | Real estate | 2026 |
| Monroe Taxi Ltd | Transport & logistics | 2026 |
| Montanas Continental Foods Ltd | Hospitality | 2023 |
| Montessori Pre-Schools Limited | Other services | 2007 |
| Montymorr Ltd | Professional & scientific | 2019 |
| Mooches With Pooches Ltd | Other services | 2022 |
| Moodle Social Media Limited | Professional & scientific | 2022 |
| Moog Digital Ltd | Information & communication | 2024 |
| Moonlight Career Guidance Ltd | Public administration | 2026 |
| Moonshine (Teesside) Ltd | Wholesale & retail | 2018 |
| Moonsoon Limited | Wholesale & retail | 2020 |
| Moore Lifting & Rigging Ltd | Construction | 2022 |
| Moore's Properties Ltd | Real estate | 2020 |
| Moores Motors Limited | Wholesale & retail | 2019 |
| Moores Motors NE Limited | Wholesale & retail | 2016 |
| Moors Estates Limited | Construction | 2019 |
| Moorside Accountancy Limited | Professional & scientific | 2025 |
| Moorthy Fuels Ltd | Wholesale & retail | 2024 |