| MG Consulting Services Ltd | Professional & scientific | 2022 |
| MG Relations Ltd | Professional & scientific | 2024 |
| MGP Nutrition Ltd | Wholesale & retail | 2015 |
| MH Global Ventures Limited | Wholesale & retail | 2025 |
| MHA Asset Management Ltd | Real estate | 2024 |
| MHA Holdings London Limited | Real estate | 2026 |
| Mhbl Limited | Construction | 2010 |
| Mhvac Services Ltd | Energy | 2021 |
| MHW Innovation & Legacy Ltd | Information & communication | 2025 |
| MI & NE Limited | Hospitality | 2020 |
| MI Associates Holdings Ltd | Real estate | 2020 |
| MIA Art Ltd | Professional & scientific | 2015 |
| Miasino Ltd | Professional & scientific | 2020 |
| Michael Anthony (Bletchley) Limited | Real estate | 2007 |
| Michael Anthony Milton Keynes (Property Letting) Limited | Administrative & support | 2008 |
| Michael Anthony Milton Keynes Limited | Administrative & support | 2008 |
| Michael Anthony Tring (Property Letting) Limited | Real estate | 2009 |
| Michael Parsons Ltd | Information & communication | 2009 |
| Michael's Bridal Fabrics Limited | Wholesale & retail | 1996 |
| Michaels Wholesale Foods Ltd. | Wholesale & retail | 1996 |
| Micheal Walsh Services Ltd | Construction | 2016 |
| Michelle Ferdinand Consultancy Limited | Health & social care | 2012 |
| Mici Studio Ltd | Construction | 2022 |
| Microtechnique Services Limited | Information & communication | 1990 |
| Micstu Development Ltd | Information & communication | 2025 |
| Mides Consulting Ltd | Professional & scientific | 2022 |
| Midge Enterprises Limited | Health & social care | 2014 |
| Midlands Car Market Limited | Wholesale & retail | 2021 |
| Midnight Blue Marketing Limited | Administrative & support | 2019 |
| Midsorella Limited | Extraterritorial | 1988 |
| Midsummer Marketing Limited | Administrative & support | 2002 |
| Midwest Commodities Limited | Wholesale & retail | 2018 |
| Midwest Polychem Limited | Manufacturing | 2020 |
| Midwinter Consulting Limited | Real estate | 2003 |
| Mienna Jones Ltd | Professional & scientific | 2025 |
| Migdale Property Limited | Construction | 2015 |
| Mighty Crew Ltd | Administrative & support | 2013 |
| Mighty Totara Management Limited | Professional & scientific | 2013 |
| Migratel Limited | Information & communication | 2001 |
| Mijns Limited | Hospitality | 2016 |
| MIK 26 Wygate Close Ltd | Real estate | 2024 |
| MIK Barton RD Ltd | Real estate | 2024 |
| MIK CGA Ltd | Real estate | 2024 |
| MIK Cherrycroft Ltd | Real estate | 2024 |
| MIK Dower House Ltd | Real estate | 2024 |
| MIK Elmwood Road Ltd | Real estate | 2024 |
| MIK Hagley Ltd | Real estate | 2024 |
| MIK Ruby House Ltd | Real estate | 2024 |
| MIK Sale Lane Ltd | Real estate | 2024 |
| Mike Stratton & Associates Ltd | Professional & scientific | 2010 |
| Mike Taylor Associates Ltd | Professional & scientific | 2009 |
| Mila UK Ltd | Information & communication | 2005 |
| Milano Logistics Ltd | Transport & logistics | 2024 |
| Mile 34 Ltd | Professional & scientific | 2012 |
| Milfold Investments Limited | Real estate | 1957 |
| Mill Holdings Limited | Real estate | 1973 |
| Millardwolf Ltd | Professional & scientific | 2026 |
| Millennia Retail Services Ltd | Wholesale & retail | 2020 |
| Millennial PUB Company Ltd | Hospitality | 2025 |
| Millie Management Limited | Financial services | 2003 |
| Millie's Day Nursery Limited | Other services | 2017 |
| Millies Day Nursery Borehamwood Limited | Health & social care | 2021 |
| Milligan Architects Ltd | Professional & scientific | 2021 |
| Milly-Reign Properties Ltd | Real estate | 2024 |
| Milvus Homes Limited | Real estate | 2017 |
| Mimarch Planning London Ltd | Professional & scientific | 2014 |
| Minaera Limited | Water & waste | 2010 |
| Mind Agency Limited | Health & social care | 2003 |
| Mind First Ltd | Health & social care | 2022 |
| Mind Font Ltd | Information & communication | 2006 |
| Mind in MID Herts | Health & social care | 2003 |
| Mint Property Group Limited | Real estate | 2016 |
| Minv Ltd | Information & communication | 2026 |
| Mirava Labs Ltd | Information & communication | 2026 |
| Miri Design Ltd | Administrative & support | 2014 |
| Mirrored Property Management Ltd | Real estate | 2022 |
| Misc Consultancy Ltd | Professional & scientific | 2019 |
| Miserden Limited | Construction | 2011 |
| Mishel Make UP Limited | Wholesale & retail | 2016 |
| Mishkaki Co Ltd | Hospitality | 2016 |
| Mishpocha Touring LLP | | 2019 |
| Miss Estruch Biology Ltd | Professional & scientific | 2023 |
| Mitchell Veneers & Components Limited | Wholesale & retail | 2002 |
| Mitogen Limited | Professional & scientific | 1996 |
| Mizio Limited | Administrative & support | 2015 |
| MJ Property & Construction Limited | Real estate | 2022 |
| Mjab Goalkeeping Limited | Arts & recreation | 2023 |
| MJC Aerospace Maintenance Limited | Manufacturing | 2019 |
| MJC Marketing & Sales Consultants Limited | Professional & scientific | 2014 |
| MJD Luxury Holidays Limited | Hospitality | 2013 |
| Mjha Services Limited | Arts & recreation | 2021 |
| MJK Vacation Homes Limited | Real estate | 2025 |
| MJM Investment Properties Limited | Real estate | 2022 |
| MJS Law Ltd | Professional & scientific | 2018 |
| MJW Carpentry & Construction Ltd. | Construction | 2014 |
| MJW Consultancy Limited | Professional & scientific | 2003 |
| MJW Holdco Ltd | Financial services | 2026 |
| Mjwgs Ltd | Administrative & support | 2016 |
| MK Chicken Ltd | Hospitality | 2025 |
| MK98 Multiworkers Ltd | Construction | 2019 |