| Miffy LET and Manage Ltd | Real estate | 2023 |
| MIG Courier Ltd | Transport & logistics | 2025 |
| Mighty West Legal Services Ltd | Professional & scientific | 2020 |
| Mike Engineering Ltd | Construction | 2025 |
| Mike Group Ltd | Financial services | 2025 |
| Mike Mills Contracts Limited | Construction | 2019 |
| Mikolutions Limited | Transport & logistics | 2020 |
| Mila Aesthetics Ltd | Other services | 2025 |
| Mila Housing Ltd | Real estate | 2024 |
| Milaf Foods UK Ltd | Hospitality | 2025 |
| Milan Ludlow Holdings Limited | Financial services | 2020 |
| Milana Fashions Ltd | Wholesale & retail | 2019 |
| Milano Creative Ltd | Manufacturing | 2018 |
| Milbury Development Company Limited | Construction | 1998 |
| Mildel Limited | Extraterritorial | 1995 |
| Mildtech UK Ltd | Manufacturing | 2022 |
| Miles Ahead HR Services Ltd | Administrative & support | 2025 |
| Miles Creations Ltd | Health & social care | 2017 |
| Miles-Brar Holdings Ltd | Administrative & support | 2020 |
| Miliqie Lounge Ltd | Hospitality | 2024 |
| Milking Solutions (UK) Limited | Manufacturing | 2002 |
| Mill Farm Fisheries Limited | Arts & recreation | 2013 |
| Mill Farm Limited | Professional & scientific | 2011 |
| Mill Parade Properties Limited | Real estate | 1958 |
| Mill Street (IOW) Residents Limited | Households | 2012 |
| Mill Street 1 Ltd | Hospitality | 2026 |
| Millar Estates Lettings Ltd | Real estate | 2024 |
| Millbrooke Enterprises CIC | Other services | 2016 |
| Millcastle Print & Carton Company Limited | Manufacturing | 2013 |
| Millenium Services Ltd | Administrative & support | 2018 |
| Miller Medical Ltd | Health & social care | 2016 |
| Miller Medical Supplies Limited | Wholesale & retail | 2009 |
| Miller Printing Solutions Ltd | Manufacturing | 2025 |
| Millstone Civils Ltd | Administrative & support | 2017 |
| Millwest Consultancy Ltd | Professional & scientific | 2023 |
| Milton Media Communications Ltd | Professional & scientific | 2022 |
| Mimi & Lola Limited | Extraterritorial | 2025 |
| Mimmis Limited | Health & social care | 2019 |
| MIN Mini Market Ltd | Wholesale & retail | 2026 |
| Mina Special Ltd | Health & social care | 2025 |
| Minara Restaurant Ltd | Hospitality | 2026 |
| Mind in Gwent | Health & social care | 1994 |
| Mindru Ltd | Transport & logistics | 2020 |
| Mindstep Foundation | Administrative & support | 2019 |
| Mini MAN Limited | Wholesale & retail | 2018 |
| Mini ME Private Day Nursery Limited | Health & social care | 2004 |
| Minibar Products Limited | Wholesale & retail | 2021 |
| Minibus Sales Limited | Wholesale & retail | 2018 |
| Minicare Ltd | Health & social care | 2012 |
| Mining INT Supplies Ltd | Wholesale & retail | 2008 |
| Ministry of POP Ltd. | Information & communication | 2002 |
| Minsa Limited | Real estate | 2026 |
| Mint 1990 Ltd | Hospitality | 2018 |
| Mint Motor Services Ltd | Wholesale & retail | 2023 |
| Mint Print 3D Limited | Manufacturing | 2025 |
| Mint Sports Management Limited | Arts & recreation | 2010 |
| Mintweld Limited | Professional & scientific | 2025 |
| Mirage Eyewear (1993) Limited | Wholesale & retail | 1992 |
| Mirage Mall Ltd | Wholesale & retail | 2023 |
| Miramare Court Management Limited | Households | 2003 |
| Mirchi Indian Takeaway Newport Ltd | Hospitality | 2019 |
| Mirka MK Accounting Ltd | Professional & scientific | 2026 |
| Mirror Dancers Ltd | Arts & recreation | 2022 |
| Misbah Health Ltd | Health & social care | 2022 |
| Misellit Marketplace Manager Ltd | Wholesale & retail | 2026 |
| Mishael Care Home Limited | Health & social care | 2004 |
| Mishael Care Services Ltd | Health & social care | 2026 |
| Miss Inspiration Limited | Extraterritorial | 2013 |
| Mister Broom Ltd | Administrative & support | 2023 |
| Mitchell Welding Ltd | Construction | 2017 |
| Miter Industrial Supplies Ltd | Wholesale & retail | 2001 |
| Mittys Limited | Other services | 2008 |
| Mivansh Infra Limited | Real estate | 2024 |
| Mixplay AU Ltd | Wholesale & retail | 2025 |
| Miyah Properties Ltd | Real estate | 2024 |
| MJ Coaching Ltd | Arts & recreation | 2023 |
| MJ Film & TV Services Ltd | Information & communication | 2026 |
| MJ Holdings (IW) Ltd | Real estate | 2023 |
| MJ Lights Ltd | Other services | 2014 |
| MJ Rail & Construction Services Ltd | Construction | 2017 |
| MJ Rubbish Removals Ltd | Water & waste | 2013 |
| MJ Software Consultancy Ltd | Information & communication | 2023 |
| Mj&Sj Powell Property Ltd | Real estate | 2026 |
| Mj's Bookkeepers Ltd | Professional & scientific | 2024 |
| Mj's Hair and Beauty Ltd | Other services | 2015 |
| MJC Construction and Rail Services Limited | Construction | 2023 |
| MJD Psychology Services Ltd | Professional & scientific | 2026 |
| MJFPROPERTIES2018 Ltd | Hospitality | 2025 |
| MJG Consult Ltd | Real estate | 2024 |
| MJG Grits Limited | Wholesale & retail | 2025 |
| MJH Investco Ltd | Financial services | 2017 |
| MJH Wind Services Ltd | Manufacturing | 2024 |
| MJI Civils Limited | Construction | 2016 |
| MJI Group Ltd | Information & communication | 2025 |
| MJK Powder Services Ltd | Manufacturing | 2025 |
| MJP Distribution Limited | Wholesale & retail | 2009 |
| MJR Lighting Limited | Wholesale & retail | 2026 |
| Mjrroofingsolutions Ltd | Construction | 2024 |
| MJS Rentals Ltd | Real estate | 2025 |
| Mjtransform Limited | Professional & scientific | 2024 |