| Mick Whylie Plumbing & Heating Ltd | Construction | 2019 |
| Mickletown Logistics Ltd | Transport & logistics | 2014 |
| Micmax Limited | Wholesale & retail | 2020 |
| Micregen Ltd | Professional & scientific | 2015 |
| Micro Analytical Solutions Limited | Professional & scientific | 2024 |
| Micro CAN Limited | Manufacturing | 2017 |
| Micronex Limited | Information & communication | 2018 |
| Microntech Global Ltd | Wholesale & retail | 2025 |
| Microwiz Technologies Limited | Information & communication | 2022 |
| MID 20 Ltd | Manufacturing | 2023 |
| MID Contracting and Consulting Ltd | Construction | 2014 |
| MID Group Services Limited | Construction | 2020 |
| MID Holding Co UK Limited | Construction | 2014 |
| MID Legal Consultancy Ltd | Administrative & support | 2026 |
| MID Legal Limited | Professional & scientific | 2026 |
| Midas Engineering Ltd | Construction | 2018 |
| Middle Chare Pharmacy Limited | Wholesale & retail | 1986 |
| Middle Eastern Restaurant Limited | Hospitality | 2025 |
| Middle Engine Software Ltd | Information & communication | 2017 |
| Middlebrook Cars Limited | Wholesale & retail | 2017 |
| Middlebrook Property Management Ltd | Households | 2020 |
| Midgley's PUB Co Limited | Professional & scientific | 2016 |
| Midland Container Storage Limited | Transport & logistics | 2009 |
| Midlandd Ltd | Transport & logistics | 2019 |
| Midlands Solar Solutions Ltd | Construction | 2026 |
| MIE4YOU Ltd | Wholesale & retail | 2019 |
| MIG Etech Ltd | Wholesale & retail | 2022 |
| MIG Monkey Welding and Fabrication Services Ltd | Manufacturing | 2017 |
| Migas Group Limited | Financial services | 2025 |
| Migas Properties Ltd | Real estate | 2023 |
| Mighty Musk Ltd | Wholesale & retail | 2021 |
| Migrant Haven Ltd | Education | 2026 |
| MIH EEA International Ltd | Wholesale & retail | 2024 |
| MIH International Solutions Ltd | Wholesale & retail | 2021 |
| MIH Services Limited | Administrative & support | 2025 |
| Miix Solutions Limited | Information & communication | 2021 |
| Mikar Holdings Limited | Real estate | 1982 |
| Mike Egan & Co Limited | Professional & scientific | 2025 |
| Mike Hewlett Education Services Limited | Education | 2013 |
| Mike Jones Telecoms Limited | Information & communication | 2025 |
| Mike LEE Properties Ltd | Real estate | 2025 |
| Mike Rogers Limited | Real estate | 2010 |
| Mikeapple Solutions Limited | Information & communication | 2017 |
| Mikkeys Energybeats Limited | Education | 2026 |
| Milan Kostacky Services Limited | Transport & logistics | 2020 |
| Milan Restaurant Limited | Hospitality | 2016 |
| Milana Bolton Ltd | Hospitality | 2026 |
| Mile END Estates LLP | | 2003 |
| Mile Lane Ltd | Wholesale & retail | 2026 |
| MILE12MARKET UK Ltd | Wholesale & retail | 2024 |
| Milehall Management Ltd | Real estate | 2005 |
| Miles Underground Limited | Mining & quarrying | 2023 |
| Milestone Enterprises Ltd | Real estate | 2010 |
| Milgauss Properties Ltd | Real estate | 2021 |
| Milie Limited | Hospitality | 2006 |
| Milk Maids Limited | Manufacturing | 2019 |
| Mill & Mortar Ltd | Wholesale & retail | 2022 |
| Mill Hill Fireworks Limited | Wholesale & retail | 2025 |
| Millbank Gardens Management Company Limited | Other services | 2000 |
| Millbrook Galleries Ltd | Arts & recreation | 2013 |
| Millbury Consultants Limited | Construction | 2009 |
| Millcroft Construction Limited | Construction | 1995 |
| Millennium Commercial Finance Limited | Financial services | 2020 |
| Millennium Court Management RTM Company Ltd | Households | 2023 |
| Millennium Finance Limited | Financial services | 2008 |
| Millennium Jeans Ltd | Wholesale & retail | 1998 |
| Millennium Legal Conveyancing Ltd | Professional & scientific | 2025 |
| Millenzo's of Westhoughton Limited | Hospitality | 2017 |
| Miller (GRF) Limited | Real estate | 2021 |
| Miller (PC) Limited | Real estate | 2021 |
| Miller (PM) Limited | Real estate | 2021 |
| Miller Goodall Ltd | Professional & scientific | 2004 |
| Miller HC Limited | Financial services | 2021 |
| Miller Hilton Limited | Wholesale & retail | 2020 |
| Miller North West Ltd | Real estate | 2020 |
| Miller Planning & Property Solutions (Bolton) Limited | Construction | 2025 |
| Miller Property Group Ltd | Real estate | 2023 |
| Millett Developments Ltd | Real estate | 2019 |
| Millfield Estates (Bolton) Limited | Real estate | 1981 |
| Millhouse Reality Group Ltd | Real estate | 2026 |
| Milli Beauty Ltd | Other services | 2019 |
| Millibyte Digital Ltd | Information & communication | 2025 |
| Millie’S Machines Limited | Wholesale & retail | 2025 |
| Milliondollar Ideas Ltd | Information & communication | 2026 |
| Millit Consultants Limited | Information & communication | 2012 |
| Millot Investments Limited | Construction | 2009 |
| Mills and Jones Limited | Construction | 1961 |
| Mills Deliveries Ltd | Transport & logistics | 2026 |
| Mills Properties (NW) Limited | Real estate | 1985 |
| Millstock Property Ltd | Real estate | 2020 |
| Millstone Building Services Ltd | Construction | 2018 |
| Millstone Design & Build Limited | Construction | 2012 |
| Milltom Builders Limited | Construction | 2005 |
| Milner Investments Limited | Real estate | 2014 |
| Milo AI Limited | Information & communication | 2023 |
| Milscrum Limited | Administrative & support | 2023 |
| Milton Knight Ltd | Professional & scientific | 2017 |
| Milvius Limited | Professional & scientific | 2024 |
| MIM and Chris Ltd | Real estate | 2024 |
| MIM Discretionary FM Limited | Financial services | 2017 |