| Mitchells Yard Limited | Households | 2025 |
| Mitech UK Limited | Information & communication | 2007 |
| Mitre Carpentry (Anglia) Limited | Manufacturing | 2023 |
| Mitro Homes Ltd | Construction | 2018 |
| MIW Logistics Corporation Limited | Administrative & support | 2014 |
| MIX Technologies Ltd | Wholesale & retail | 2018 |
| MJ Barbers Limited | Other services | 2017 |
| MJ Cornfield Ltd | Financial services | 2026 |
| MJ Drive Ltd | Transport & logistics | 2016 |
| MJ Engineering & Surveying Ltd | Other services | 2018 |
| MJ Infra Ltd | Professional & scientific | 2025 |
| MJ Installs Ltd | Information & communication | 2015 |
| MJ Peachment Limited | Construction | 2016 |
| MJ Property Management Ltd | Real estate | 2026 |
| Mj's Retailers Ltd | Wholesale & retail | 2023 |
| MJA Consultancy Limited | Wholesale & retail | 2000 |
| MJA Events Ltd | Hospitality | 2024 |
| MJB Consultants Ltd | Health & social care | 2019 |
| MJB Scaffolders Limited | Construction | 2003 |
| MJC Plumbing Ltd | Construction | 2025 |
| MJC Scaffolding Ltd | Construction | 2021 |
| MJD Building & Maintenance Limited | Construction | 2014 |
| MJE Services Limited | Manufacturing | 2026 |
| MJG Mortgages Ltd | Financial services | 2019 |
| MJH Brickwork Limited | Construction | 2026 |
| Mjil Ltd | Professional & scientific | 2025 |
| Mjjt Consulting Limited | Professional & scientific | 2007 |
| MJK Commercial Finance Ltd | Financial services | 2019 |
| MJK Plumb&Heat Ltd | Construction | 2023 |
| MJL Consultancy Services Ltd | Construction | 2015 |
| MJM Building Services Ltd | Construction | 2006 |
| MJM Financial Services Ltd | Financial services | 2019 |
| MJM Football Consultancy Limited | Arts & recreation | 2009 |
| MJM Utilities Ltd | Administrative & support | 2025 |
| MJP Conveyancing Limited | Professional & scientific | 2012 |
| MJP Property Holdings Limited | Real estate | 2025 |
| Mjrr Holdings Limited | Financial services | 2024 |
| MJS Holdco Ltd | Real estate | 2024 |
| Mjtb Consulting Limited | Professional & scientific | 2020 |
| MJZ Pharma Ltd | Wholesale & retail | 2021 |
| MK Builder (NFK) Ltd | Construction | 2022 |
| MK Durrant Properties Ltd | Real estate | 2025 |
| MK Metal Work Ltd. | Manufacturing | 2021 |
| Mk&W Ltd | Health & social care | 2019 |
| MKC Building and Landscaping Limited | Construction | 2016 |
| MKC Properties Norfolk Ltd | Real estate | 2022 |
| Mkcc (Norfolk) Limited | Mining & quarrying | 2024 |
| MKD Pigs Ltd | Agriculture & fishing | 2018 |
| MKDJLW1 Ltd | Financial services | 2024 |
| MKE Planning Ltd | Administrative & support | 2024 |
| MKH Transport Ltd | Transport & logistics | 2017 |
| MKM Communications Ltd | Administrative & support | 2017 |
| Mkolev Logistics Ltd | Transport & logistics | 2016 |
| MKU South Shields Limited | Hospitality | 2018 |
| ML Cors Ltd | Financial services | 2024 |
| ML Fencing Services Ltd | Construction | 2025 |
| ML Land Limited | Real estate | 2003 |
| ML Portal Investments Ltd | Real estate | 2025 |
| ML Worcester Limited | Hospitality | 2021 |
| MLA Accountancy Ltd | Professional & scientific | 2018 |
| MLA Holdings Ltd | Professional & scientific | 2024 |
| MLD Property Investments Ltd | Real estate | 2024 |
| Mlnz Limited | Professional & scientific | 2022 |
| Mlst Limited | Wholesale & retail | 2024 |
| MM Appliance Repairs Ltd | Other services | 2026 |
| MM Executive Travel Ltd | Transport & logistics | 2021 |
| MM Hair ( Norwich ) Limited | Wholesale & retail | 2013 |
| MM Holidays Ltd | Hospitality | 2021 |
| MM Law Ltd | Professional & scientific | 2020 |
| MM2 Limited | Wholesale & retail | 2003 |
| MMA Assessment and Development Limited | Professional & scientific | 2014 |
| Mmalinowska Consultancy Ltd | Professional & scientific | 2016 |
| MMC Partners Limited | Real estate | 2025 |
| MMC Properties Limited | Real estate | 2002 |
| MMD Bookkeeping Limited | Professional & scientific | 2016 |
| Mmhv Electrical Motor Services Ltd | Professional & scientific | 2025 |
| MMK Legal Services Ltd | Professional & scientific | 2017 |
| Mmwb Property Ltd | Real estate | 2025 |
| MO Diner Ltd | Hospitality | 2023 |
| MO O'Hara Ltd | Information & communication | 2016 |
| MO11NUX Holdings Limited | Real estate | 2025 |
| Mobile Appster Limited | Information & communication | 2015 |
| Mobile Fresh Ltd | Wholesale & retail | 2008 |
| Mobile Money Limited | Financial services | 1998 |
| Mobile Visual Information Systems Limited | Administrative & support | 2012 |
| Mobiled Ltd | Wholesale & retail | 2022 |
| Mobileplace Ltd | Wholesale & retail | 2026 |
| Mobilityways Limited | Information & communication | 2000 |
| Moco Kitchen Limited | Hospitality | 2019 |
| MOD One Limited | Wholesale & retail | 2011 |
| Moda Turkish Barber Limited | Other services | 2022 |
| Modbay Limited | Construction | 1989 |
| Mode Barber Studio Ltd | Other services | 2025 |
| Model Fans Management Limited | Information & communication | 2025 |
| Models Direct (UK) Limited | Administrative & support | 1994 |
| Models Direct Limited | Professional & scientific | 2004 |
| Moderate Flank Ltd | Professional & scientific | 2022 |
| Modern Garage Classics Limited | Wholesale & retail | 2019 |
| Modern MAN Coach Ltd | Professional & scientific | 2021 |
| Modern Method Construction Limited | Real estate | 2019 |