| Middle East Marketing Consultant Limited | Professional & scientific | 2025 |
| Middleton Manufacturing Limited | Manufacturing | 2017 |
| Middz Market Ltd | Wholesale & retail | 2024 |
| Midland Computer Services Limited | Manufacturing | 1996 |
| Midland Computer Solutions LLP | | 2014 |
| Midland Dreamz Limited | Information & communication | 2015 |
| Midland Estates & Lettings Limited | Real estate | 2025 |
| Midland Lifting Limited | Manufacturing | 2016 |
| Midland Regional Investments Limited | Real estate | 2005 |
| Midlands Technical Mouldings (Holdings) Limited | Professional & scientific | 2006 |
| Midpoint Communications Limited | Information & communication | 2016 |
| Midpoint Homes Limited | Real estate | 2020 |
| Midpoint Marketing Ltd | Information & communication | 2013 |
| Midpoint Property Ltd | Real estate | 2019 |
| Midpoint Telecoms Ltd | Information & communication | 2019 |
| Midsummer Rental Ltd | Real estate | 2026 |
| Midsummer Veterinary Services Limited | Real estate | 1999 |
| Midwest GH Ltd | Real estate | 2025 |
| MIG Corporate Ltd | Professional & scientific | 2015 |
| MIG Property Investments Unlimited | Other services | 2022 |
| Might BE Robot Ltd | Information & communication | 2023 |
| Mighty Red MK Limited | Hospitality | 2020 |
| Migrash Ltd | Public administration | 2022 |
| Mihai Ciobanu Ltd | Construction | 2015 |
| Mihaid Ltd | Transport & logistics | 2026 |
| Mihailt Ltd | Transport & logistics | 2021 |
| Mijp Ltd | Other services | 2019 |
| MIK Tech Limited | Information & communication | 2018 |
| Mikcan & Co Limited | Real estate | 2015 |
| Mike & Sons - ALL Things Furniture MK Ltd | Wholesale & retail | 2023 |
| Mike Hughes Advisory Limited | Professional & scientific | 2022 |
| Mike Smith Lighting Limited | Arts & recreation | 2014 |
| Mike Veale and Associates Limited | Professional & scientific | 2019 |
| Mikebee PVT Ltd | Health & social care | 2024 |
| Mikejoy Ltd | Health & social care | 2016 |
| Mikenla Childcare Limited | Administrative & support | 2020 |
| MIL Property Group Ltd | Real estate | 2022 |
| Mila Rose of London Limited | Wholesale & retail | 2022 |
| Milaanstouch Ltd | Wholesale & retail | 2025 |
| Milagrillo Ltd | Real estate | 2025 |
| Mile Zero Coffee Ltd | Hospitality | 2025 |
| Milecroft Homes Limited | Real estate | 2002 |
| Milehams Car Parts Limited | Wholesale & retail | 2021 |
| Milen Mitev Dimitrov Limited | Transport & logistics | 2019 |
| Milenco Limited | Manufacturing | 1993 |
| Milescale Limited | Extraterritorial | 1987 |
| Milestone Automotive Limited | Wholesale & retail | 2020 |
| Milestone Car Parts Limited | Wholesale & retail | 2025 |
| Milestones MK Limited | Professional & scientific | 2024 |
| Milfos UK Limited | Manufacturing | 2011 |
| Milfreds Care Ltd | Health & social care | 2020 |
| Milily Services Ltd | Health & social care | 2021 |
| Milimani Ltd | Professional & scientific | 2012 |
| Military Storage Solutions Ltd | Public administration | 2019 |
| Militech Ltd | Information & communication | 2020 |
| Milk & Beans Coffee Roasters Ltd | Manufacturing | 2021 |
| Milk & Beans Vintage Ltd | Wholesale & retail | 2024 |
| Milkchecker Ltd | Other services | 2024 |
| Mill Road Land Limited | Real estate | 2018 |
| Millbank Property Management Limited | Real estate | 2008 |
| Millbeck Ross | Financial services | 2017 |
| Mille-Amp Electrical Services Limited | Other services | 2018 |
| Millenium Catering Equipment Limited | Other services | 2006 |
| Millennial Holdings Ltd | Wholesale & retail | 2025 |
| Millennium Falcon Transport Solutions Ltd | Transport & logistics | 2020 |
| Miller & Young Ltd | Administrative & support | 2011 |
| Miller Carpentry Ltd | Construction | 2020 |
| Milleter Ltd | Other services | 2024 |
| Millfield Greenway Business Park Management Limited | Real estate | 2007 |
| Millie Mason Properties Ltd | Real estate | 2026 |
| Millington Associates Limited | Manufacturing | 1999 |
| Millington's Removals Limited | Transport & logistics | 2018 |
| Millington's Storage Ltd | Transport & logistics | 2022 |
| Millpeace Enterprises Ltd | Arts & recreation | 2010 |
| Mills Trading Ltd | Professional & scientific | 2022 |
| Millsaw Carpentry & Construction Limited | Manufacturing | 2019 |
| Millstone Edge Limited | Construction | 2025 |
| Milltech Recruitment Ltd | Wholesale & retail | 2014 |
| Millteq LLP | | 2016 |
| Millèr Beauty Limited | Wholesale & retail | 2023 |
| Milocca Group Limited | Financial services | 2026 |
| Milocca Properties Limited | Real estate | 2026 |
| Milou&Co Ltd | Other services | 2016 |
| Milton & Crown Certified Accountants Ltd | Transport & logistics | 2014 |
| Milton Car Services Limited | Transport & logistics | 2021 |
| Milton Creative Print Ltd | Manufacturing | 2014 |
| Milton Engineering Ltd | Construction | 2021 |
| Milton Hauleage Ltd | Transport & logistics | 2020 |
| Milton Keynes Accountants Limited | Professional & scientific | 2023 |
| Milton Keynes ALL Trades Limited | Construction | 2012 |
| Milton Keynes Angling Limited | Real estate | 1996 |
| Milton Keynes Animal Hospital Limited | Real estate | 2001 |
| Milton Keynes Archery Ltd | Wholesale & retail | 2013 |
| Milton Keynes Automotive Integration Ltd | Professional & scientific | 2025 |
| Milton Keynes Breakdance and Activities Community Interest Company | Education | 2023 |
| Milton Keynes Building Services Ltd | Construction | 2019 |
| Milton Keynes Business Leaders Partnership Limited | Other services | 2008 |
| Milton Keynes Business Solutions Limited | Administrative & support | 2012 |
| Milton Keynes Cheerleading Academy (Mkca) C.I.C. | Arts & recreation | 2018 |
| Milton Keynes Chemicals Limited | Manufacturing | 1973 |