| MM Capital Carry LLP | | 2020 |
| MM Capital UK Ltd | Real estate | 2020 |
| MMB Energy Ltd | Professional & scientific | 2016 |
| MN Vehicles Ltd | Wholesale & retail | 2023 |
| MNB Consultancy Ltd | Professional & scientific | 2011 |
| MNG Care at Home Services Limited | Health & social care | 2021 |
| MO & Co Contracts Limited | Administrative & support | 2007 |
| Moat Hall Barns Ltd | Other services | 2022 |
| Moat House Fields (Marston Green) Management Limited | Households | 2013 |
| Mobhut Shrewsbury Ltd | Wholesale & retail | 2023 |
| Mobile Equine Solutions Limited | Transport & logistics | 2021 |
| Mobile Phone Clinic Limited | Wholesale & retail | 2020 |
| Modara Consultancy Limited | Information & communication | 2024 |
| Modern Contradiction Limited | Wholesale & retail | 2017 |
| Modern Gent Ltd | Wholesale & retail | 2015 |
| Modo UK Limited | Wholesale & retail | 2007 |
| Module Media Limited | Administrative & support | 2001 |
| Mohee Urology Limited | Health & social care | 2019 |
| Mojo (London) Ltd | Information & communication | 2023 |
| Mojoy Limited | Wholesale & retail | 2021 |
| Molica Investments LLP | | 2005 |
| Momuma Limited | Real estate | 2008 |
| Money Relevance Limited | Financial services | 2011 |
| Moneypire Ltd | Extraterritorial | 2023 |
| Moneypitch Company Limited | Financial services | 1993 |
| Monkmoor Bathrooms Limited | Wholesale & retail | 2008 |
| Monkmoor Dental Practice Limited | Health & social care | 2013 |
| Monkmoor Industrial Estate Limited | Real estate | 1981 |
| Monks Estate & Letting Agents Limited | Real estate | 2014 |
| Monstrous Makings Ltd | Manufacturing | 2018 |
| Montana Holdings Limited | Professional & scientific | 2007 |
| Montford Bridge Management Company Limited | Households | 2009 |
| Montford Consulting Ltd | Information & communication | 2023 |
| Montford Properties (Hadnall) Limited | Construction | 2026 |
| Montford Properties Ltd | Construction | 2016 |
| Montpelier Brighton Management Ltd | Real estate | 2022 |
| Monument Court Management (Hagley) Limited | Households | 2004 |
| Monument Digital Limited | Information & communication | 2021 |
| Moody Accounting Limited | Professional & scientific | 2022 |
| Moofi Arts Ltd | Wholesale & retail | 2021 |
| Moonred Limited | Hospitality | 2016 |
| Moonrise Property | Professional & scientific | 2020 |
| Moor Engineering Services Ltd | Professional & scientific | 2012 |
| Moor Farm Cafe Limited | Hospitality | 2023 |
| Moor Farm Polo Club LLP | | 2017 |
| Moorhen Close RTM Limited | Households | 2006 |
| Mooschie Ltd | Manufacturing | 2013 |
| Moose Records Limited | Information & communication | 2023 |
| Morbury Homes Limited | Professional & scientific | 2001 |
| Moreton Point Apartments Management Company Ltd | Real estate | 2008 |
| Morgan Human Systems Ltd | Education | 2020 |
| Morgan Jones & Co Accountants Limited | Professional & scientific | 2020 |
| Morgan's Vehicle Solutions Ltd | Transport & logistics | 2023 |
| Morgans Property Holdings Limited | Households | 2025 |
| Morgan’S MOT & Repair Centre Limited | Wholesale & retail | 2026 |
| Morland Capital Investments Ltd | Professional & scientific | 2012 |
| Morland Capital Partners Limited | Real estate | 2019 |
| Morland Capital Partners NO1 Limited | Real estate | 2019 |
| Morland Capital Partners NO2 Limited | Real estate | 2020 |
| Morland Rental Limited | Real estate | 2024 |
| Morocco Pantry Ltd | Hospitality | 2024 |
| Morris & Company (2004) Limited | Extraterritorial | 1985 |
| Morris & Company (Shrewsbury) Limited | Real estate | 2004 |
| Morris & Company Limited | Construction | 1922 |
| Morris and Company Trust Fund Limited | Financial services | 1949 |
| Morris Capital Limited | Extraterritorial | 1947 |
| Morris Communications Limited | Extraterritorial | 2002 |
| Morris Escapes Limited | Extraterritorial | 2026 |
| Morris Estates (Shrewsbury) Limited | Extraterritorial | 1986 |
| Morris Food Limited | Extraterritorial | 1986 |
| Morris Light & Power Limited | Manufacturing | 1980 |
| Morris Oils Limited | Extraterritorial | 2015 |
| Morris Property Limited | Construction | 1995 |
| Morris Residential Limited | Extraterritorial | 2003 |
| Morris Retirement Limited | Extraterritorial | 2018 |
| Morris Site Machinery Limited | Wholesale & retail | 1972 |
| Morris Sports & Social Club | Arts & recreation | 2024 |
| Mortgage Cost Comparison Ltd | Financial services | 2021 |
| Mortgage Matters (Cheshire) Limited | Financial services | 2016 |
| Mortimer Development Services Ltd | Construction | 2021 |
| Morton Property Limited | Construction | 2009 |
| Morton-Wilson Associates Limited | Financial services | 1999 |
| Moscar Properties Limited | Real estate | 2026 |
| Moselhi and Bottomley Limited | Health & social care | 2016 |
| Moskath Ltd | Health & social care | 2016 |
| Mossco LLP | | 2012 |
| Motatech Limited | Wholesale & retail | 2014 |
| Mother Hubbard Residents Management Company Limited | Households | 2003 |
| Mother Nature and SON Limited | Administrative & support | 2025 |
| Mother Nature TP Ltd | Manufacturing | 2023 |
| Mothership Life C.I.C. | Health & social care | 2025 |
| Motofactors Ltd | Extraterritorial | 2013 |
| Motor Racing Live Limited | Arts & recreation | 2007 |
| Motorsport Consultancy Ltd | Professional & scientific | 2025 |
| Mottay Ltd | Real estate | 2000 |
| Mottram HAY, Straw and Transport Ltd. | Transport & logistics | 2017 |
| Motum Health and Wellness Ltd | Health & social care | 2023 |
| Motum Properties Ltd | Real estate | 2026 |
| Moulson Process Plant Limited | Professional & scientific | 1984 |
| Mount Canon Holdings Limited | Financial services | 2018 |