| Midwood 23 Ltd | Real estate | 2026 |
| Mightie Bites Ltd | Hospitality | 2017 |
| Migrate My Accounts Limited | Information & communication | 2024 |
| Miiko Ltd | Hospitality | 2018 |
| Mijora Limited | Wholesale & retail | 2025 |
| Mika Recruitment and Consulting Limited | Administrative & support | 2015 |
| Mike & JO Limited | Information & communication | 2018 |
| Mike Thompson Partnership Ltd | Real estate | 2019 |
| Mike Wills Marine Ltd | Manufacturing | 2026 |
| Mila Consultancy Ltd | Professional & scientific | 2018 |
| Mila Holiday Lets Limited | Hospitality | 2024 |
| Miles & Co Ltd. | Professional & scientific | 2002 |
| Miles Croft Ltd | Other services | 2019 |
| Miles Engineering Consultants Limited | Administrative & support | 2017 |
| Miles Phillips Property Consultants Limited | Real estate | 2018 |
| Milestone Property Developments (Dorset) Limited | Real estate | 1995 |
| Milford Commercials Limited | Real estate | 2024 |
| Militex (Sales) Limited | | 1981 |
| Mill and Ball Ltd | Wholesale & retail | 2020 |
| Milld& Limited | Wholesale & retail | 2025 |
| Milldever Group Ltd | Wholesale & retail | 2024 |
| Millennium Film Finance Limited | Information & communication | 2004 |
| Millennium London Property Services LLP | | 2014 |
| Miller Bros. & F.P. Butler Limited | Other services | 1958 |
| Millhouse (South) Limited | Real estate | 2013 |
| Millhouse Epsom Limited | Real estate | 2018 |
| Millmoor Financial Ltd | Financial services | 2020 |
| Millmoor Ltd | Information & communication | 2018 |
| Mills Personal Training Bournemouth Limited | Arts & recreation | 2018 |
| Millstone Holdings Limited | Professional & scientific | 1994 |
| Millturn CNC Limited | Professional & scientific | 2003 |
| Milly Lily Limited | Professional & scientific | 2026 |
| Milos Holdings Limited | Professional & scientific | 2023 |
| Milsom Avenue Ltd | Real estate | 2023 |
| Mimini Ltd | Wholesale & retail | 2026 |
| Minamar 2026 Ltd | Wholesale & retail | 2026 |
| Mince PIE Media Ltd | Arts & recreation | 2025 |
| Mind Guiders Ltd | Health & social care | 2022 |
| Mindbodyconnection Ltd | Health & social care | 2024 |
| Mindfituk Ltd | Health & social care | 2024 |
| Mindovate Ltd | Wholesale & retail | 2025 |
| Minds of Maja Ltd | Information & communication | 2025 |
| Mindsculpt Ltd | Education | 2022 |
| Ming Furniture Ltd | Wholesale & retail | 2023 |
| Mini Pixel Ltd | Information & communication | 2021 |
| Miniature Bearings Limited | Information & communication | 1982 |
| Minifit Ltd | Manufacturing | 2025 |
| Minigamegift Ltd | Professional & scientific | 2020 |
| Minimalist Jewellery Ltd | Wholesale & retail | 2023 |
| Minimoko Ltd | Administrative & support | 2009 |
| Miniverse Ltd | Administrative & support | 2020 |
| Minonzung Ltd | Wholesale & retail | 2025 |
| Minos Limited | Extraterritorial | 1999 |
| Mint Glazing Limited | Construction | 2021 |
| Mint Homecare Limited | Health & social care | 2025 |
| Mint Indian Restaurant Ltd | Hospitality | 2018 |
| Mint Marketing Ltd | Professional & scientific | 2005 |
| Mint Spiral Limited | Professional & scientific | 2023 |
| Mintmead Limited | Professional & scientific | 2014 |
| MIR Home Ltd | Wholesale & retail | 2025 |
| Miracle Shop Limited | Wholesale & retail | 2025 |
| Miraculum Films Ltd | Information & communication | 2024 |
| Mirage Designs Limited | Wholesale & retail | 2017 |
| Mircle Ltd | Health & social care | 2025 |
| Miri Building Services Ltd | Construction | 2012 |
| Mirmur Ltd | Wholesale & retail | 2023 |
| Mirovetix Ltd | Manufacturing | 2025 |
| Mirror Image Clinic Ltd | Health & social care | 2022 |
| Mirror Mind Therapy Ltd | Health & social care | 2025 |
| Mirthwood Ltd | Wholesale & retail | 2025 |
| Misayade Ltd | Information & communication | 2021 |
| Miscon Limited | Wholesale & retail | 2025 |
| Misk Collections Ltd | Wholesale & retail | 2024 |
| Miso Consulting Limited | Professional & scientific | 2022 |
| Misplaced Roots Ltd | Wholesale & retail | 2022 |
| Mission to Manage Money Ltd | Wholesale & retail | 2023 |
| Mission Town Planning Ltd | Professional & scientific | 2020 |
| Mistglade Ltd | Wholesale & retail | 2026 |
| Mitchell Bunt Aviation and IT Services Ltd | Information & communication | 2018 |
| Mitral Surgery UK Limited | Health & social care | 2022 |
| Mixhackers Ltd | Extraterritorial | 2025 |
| Mixtli Consulting Ltd | Information & communication | 2023 |
| Mizpah Property Holdings Limited | Real estate | 2017 |
| MJ Bird Electrical Ltd | Construction | 2016 |
| MJ Delivered Limited | Wholesale & retail | 2024 |
| MJ Grey Ltd | Wholesale & retail | 2022 |
| MJ Quality Toys Ltd | Wholesale & retail | 2012 |
| MJ Training Limited | Information & communication | 2009 |
| MJA Catering Services Ltd | Hospitality | 2026 |
| MJB Installation Services Ltd | Construction | 2018 |
| MJB Trade Windows Ltd | Construction | 2009 |
| MJC Doors Limited | Construction | 2017 |
| MJC Land and Farm Limited | Agriculture & fishing | 2026 |
| MJC Marine Ltd | Extraterritorial | 2019 |
| MJH Developments Limited | Real estate | 1999 |
| MJL House Renovations Ltd | Real estate | 2023 |
| MJM Delivery and Transportation Ltd | Transport & logistics | 2025 |
| MJR Renovations Ltd | Construction | 2020 |
| MJS Independent Consulting Ltd | Professional & scientific | 2019 |
| MJV Carpentry Ltd | Construction | 2019 |