| Mhje Ltd | Transport & logistics | 2026 |
| MI Casa Mortgages Ltd | Financial services | 2020 |
| MI Casa Tax & Accounts Ltd | Financial services | 2021 |
| MI Foundation | Education | 2018 |
| MIA Croydon Property Ltd | Real estate | 2017 |
| MIA Mamma Foundation CIC | Education | 2018 |
| MIA Royston Limited | Real estate | 2018 |
| Miad Hire Ltd | Administrative & support | 2014 |
| Miah Management Limited | Hospitality | 2004 |
| Miaj Holdings Limited | Real estate | 2026 |
| Miali London Ltd | Hospitality | 2026 |
| Mian Environment Limited | Administrative & support | 2024 |
| Mian Trdr Ltd | Wholesale & retail | 2022 |
| Michael Brothers ( U K ) Limited | Real estate | 2009 |
| Michael Emmanuel Developments Ltd | Real estate | 2024 |
| Michael Furlonger Ltd | Professional & scientific | 2023 |
| Michael Henry Civil Engineering Limited | Construction | 1999 |
| Michael Henry Properties Limited | Construction | 2013 |
| Michael Kirk and Partners Limited | Administrative & support | 1987 |
| Michael L Harper Limited | Professional & scientific | 2017 |
| Michel Michaelides Ltd | Health & social care | 2010 |
| Michele Pascarella Limited | Professional & scientific | 2025 |
| Michelle Dzvairo Limited | Health & social care | 2015 |
| Michelle Louise Limited | Other services | 2005 |
| Micklefield Court Limited | Households | 1998 |
| Micro E-Merchandiser Ltd | Wholesale & retail | 2019 |
| Micro Properties Management Limited | Real estate | 2023 |
| Microbore Merchants Limited | Administrative & support | 1982 |
| Microcem Finishes Ltd | Construction | 2026 |
| Microdose Direct Ltd | Manufacturing | 2023 |
| Micromerchandiser Limited | Transport & logistics | 2011 |
| Micronoesis Ltd. | Information & communication | 2018 |
| Microquery Limited | Information & communication | 2010 |
| Microxtec Ltd | Construction | 2018 |
| Micsha Associates Ltd | Administrative & support | 2009 |
| Micsuk Limited | Health & social care | 2015 |
| Midas Shine Cleaning Company Ltd | Administrative & support | 2026 |
| Midasphere Ltd | Information & communication | 2025 |
| Middlesham Flat Management Company Limited | Households | 1978 |
| Midland Apartments RTM Company Limited | Households | 2024 |
| Midland Desserts Limited | Hospitality | 2026 |
| Midland Property Group Limited | Real estate | 2017 |
| Midland Shopfronts Limited | Manufacturing | 2019 |
| MIE ALI Didi Ltd | Professional & scientific | 2023 |
| Mighty Fortress Estates Ltd | Real estate | 2025 |
| Mighty MEN of Valour | Other services | 2005 |
| Mih&Dar International Courier Ltd | Transport & logistics | 2025 |
| Mihaela D Care Limited | Health & social care | 2025 |
| Mihaela Dobos Ltd | Health & social care | 2025 |
| Mihai V Delivery Ltd | Transport & logistics | 2024 |
| MIK Assets Limited | Financial services | 2019 |
| Mike Copeman Limited | Wholesale & retail | 2002 |
| Mike Flynn Associates Limited | Professional & scientific | 1999 |
| Mike Moran IFA Ltd | Other services | 2019 |
| Mike Parry Promotions Ltd | Information & communication | 2011 |
| Mike the Mechanic Ltd | Wholesale & retail | 2025 |
| Mikjad Services Limited | Wholesale & retail | 2016 |
| Mikoo Properties Ltd | Real estate | 2022 |
| Milcha Properties Limited | Extraterritorial | 2023 |
| Mildenhall Realisations (2000) Limited | Wholesale & retail | 1983 |
| Mile One Clothing Limited | Wholesale & retail | 2025 |
| Mileben Group Ltd | Other services | 2026 |
| Milesi & Partners Ltd | Wholesale & retail | 2016 |
| Milestone Gate Limited | Real estate | 2003 |
| Milford Grange (Poplar Lane) Winnersh Management Company Limited | Households | 2011 |
| Milford House Freehold Limited | Households | 2005 |
| Milford House Management Company Limited | Households | 1988 |
| Mill Capital Ltd | Construction | 2021 |
| Mill Gate Aspull Management Limited | Households | 2011 |
| Mill Green (Halstead) Management Limited | Households | 2008 |
| Mill Green (Marple) Management Limited | Households | 2008 |
| Mill Green Park Number One (Congleton) Management Company Limited | Households | 2003 |
| Mill Hill Management Limited | Households | 2021 |
| Mill Lane (Sawston) Management Company Ltd | Households | 2018 |
| Mill Lane MX Limited | Arts & recreation | 2016 |
| Mill Lane Settle Management Company Limited | Households | 2020 |
| Mill View (Allington) Management Company Limited | Households | 2001 |
| Mill VUE Management Company Limited | Households | 2007 |
| Millbrook Building Consultancy Ltd | Construction | 2018 |
| Millbrook Street Management Company Limited | Households | 2014 |
| Millennial Elite London Ltd | Administrative & support | 2023 |
| Millennium Croydon Ltd | Other services | 2011 |
| Millennium Goals Limited | Real estate | 2000 |
| Millennium Motors International Ltd | Wholesale & retail | 2026 |
| Millennium Production Music Limited | Arts & recreation | 1999 |
| Miller 1890 Limited | Administrative & support | 2015 |
| Miller Miller Ltd | Other services | 2017 |
| Miller's Croft Management Company Limited | Households | 1989 |
| Millers Carpentry Ltd | Manufacturing | 2024 |
| Millers Croft (Edenbridge) Management Company Limited | Households | 2013 |
| Millers Mews Limited | Households | 1989 |
| Millharbour Management Limited | Households | 2002 |
| Millie Minks Ltd | Other services | 2023 |
| Milliminds Limited | Education | 2021 |
| Millington Rose Ltd | Real estate | 2025 |
| Millmask Limited | Professional & scientific | 2001 |
| Millo Ltd | Information & communication | 2025 |
| Millones Capital Ltd | Financial services | 2025 |
| Mills Accountancy and Payroll Services Limited | Professional & scientific | 2014 |
| Millside (Evesham) Management Company Limited | Households | 2003 |