| MHR Fitness Ltd | Arts & recreation | 2019 |
| MHR Markets Ltd | Other services | 2023 |
| MHT Renovations Limited | Construction | 2025 |
| Miah Curry House Ltd | Hospitality | 2011 |
| MIC and Couch Entertainment Ltd | Other services | 2024 |
| Michael Haverly Estates Ltd | Real estate | 2013 |
| Michael Matthews Ltd | Transport & logistics | 2021 |
| Michael Rhodes Limited | Real estate | 1994 |
| Michael Stanton Medico-Legal Limited | Professional & scientific | 2026 |
| Micheldever Station Developments Limited | Construction | 2024 |
| Mickilner Limited | Construction | 2024 |
| Microlink Global Limited | Information & communication | 2013 |
| Micropol Fiberoptics Ltd | Manufacturing | 2024 |
| Mid-Life Wargaming Ltd | Administrative & support | 2024 |
| Midanbury Site Services Ltd | Construction | 2009 |
| Midforest Tree Care Ltd | Administrative & support | 2012 |
| Midhurst Court Management Group Limited | Households | 2022 |
| Midnight Starz Limited | Wholesale & retail | 2025 |
| Mighty Couriers Limited | Transport & logistics | 2010 |
| MIH Mortgages Ltd | Financial services | 2020 |
| Mike Chambers Consultancy Limited | Arts & recreation | 2014 |
| Mike Chandler School of Motoring Ltd | Other services | 2011 |
| Mike Jacobs (Builders) Limited | Construction | 2004 |
| Mike Thurston Ltd | Wholesale & retail | 2018 |
| Miles Stone Holdings Limited | Financial services | 2012 |
| Miles Stone Limited | Wholesale & retail | 2012 |
| Mill Brickwork Limited | Construction | 2022 |
| Mill House Management Company Limited(The) | Households | 1986 |
| Miller Diagnostic Imaging Limited | Health & social care | 2019 |
| Milton Rhodes Limited | Professional & scientific | 2005 |
| Mimobileclub Limited | Wholesale & retail | 2021 |
| Mind & Matter Consulting Limited | Professional & scientific | 2021 |
| Mind Fitness Learning Ltd | Education | 2017 |
| Minimax Automobile Parts Recycling Ltd | Wholesale & retail | 2025 |
| Minimax Pharmaceuticals Ltd | Wholesale & retail | 2014 |
| Minmar (839) Limited | Extraterritorial | 2007 |
| Mint Kitchens & Bathrooms Ltd | Construction | 2024 |
| Mint Signs and Graphics Limited | Professional & scientific | 2011 |
| Minxyj Ltd | Arts & recreation | 2025 |
| Mirion Technologies (IST) Limited | Manufacturing | 1970 |
| Misha Cosmetics Limited | Wholesale & retail | 2018 |
| MIT Fiscal Ltd | Financial services | 2019 |
| Mitchell & Partners (Farnborough) Ltd | Wholesale & retail | 2008 |
| Mitchell Properties 2013 Limited | Financial services | 2013 |
| Mitchell Properties Limited | Real estate | 1988 |
| Mitchtv Steadicam Limited | Administrative & support | 2009 |
| Mixitupfitness Limited | Extraterritorial | 2017 |
| Mixmelt Ltd | Manufacturing | 2015 |
| MJ Brooker Plumbing and Heating Limited | Construction | 2006 |
| MJB Cleaning Ltd | Other services | 2007 |
| MJH Builders (Hampshire) Ltd | Construction | 2015 |
| MJL Tackle Ltd | Wholesale & retail | 2015 |
| MK Roofing (Hampshire) Ltd | Construction | 2026 |
| MK Scaffolding Specialists Limited | Construction | 2013 |
| MK Technical Limited | Information & communication | 2011 |
| ML Electrical & Facilities Services Ltd | Construction | 2021 |
| MLC S&T Installations Ltd | Construction | 2016 |
| MLJ Innovations Ltd | Information & communication | 2025 |
| Mmccts Limited | Information & communication | 2019 |
| MMP Hedge END Limited | Manufacturing | 2011 |
| MOB Zone Limited | Other services | 2020 |
| Mobolaji & Sons Properties Ltd | Real estate | 2021 |
| Modsarie Holdings Limited | Professional & scientific | 2015 |
| Modulation Telecom Limited | Information & communication | 2019 |
| Moghul the Great Ltd | Hospitality | 2025 |
| Mogzilla Books Ltd | Wholesale & retail | 2023 |
| Mojeda Investments Limited | Real estate | 2021 |
| Molchie Enterprises Ltd | Hospitality | 2025 |
| Moldon Ltd | Hospitality | 2025 |
| Momentum Campaign (Services) Ltd | Other services | 2015 |
| Monahans Transport Ltd | Transport & logistics | 2015 |
| Monarch Construction Division Ltd | Manufacturing | 2025 |
| Moncarda Consulting Limited | Professional & scientific | 2024 |
| Money Magic Ltd | Information & communication | 2026 |
| Mongoose Capital Ltd | Financial services | 2024 |
| Mongoose Holdings Limited | Financial services | 2024 |
| Mongoose Property Limited | Real estate | 2022 |
| Mongoose Social Limited | Professional & scientific | 2020 |
| Monks Brook Industrial Park Management Company Limited | Households | 1985 |
| Monks Brook Motors Ltd | Wholesale & retail | 2002 |
| Monks Brook Property (Hampshire) Limited | Real estate | 2014 |
| Monks Brook Property LLP | | 2008 |
| Monmouth Investments Limited | Real estate | 2017 |
| Monster Smash Studio Limited | Arts & recreation | 2020 |
| Monsy Limited | Wholesale & retail | 2015 |
| Monsy Properties Limited | Real estate | 2024 |
| Montblanc Services Ltd | Professional & scientific | 2019 |
| Montfort College Limited | Households | 1985 |
| Monty Consulting Ltd | Information & communication | 2020 |
| Monty Dog Events Ltd | Hospitality | 2021 |
| Moody Rogers Groundworks & Civil Engineering Limited | Construction | 2020 |
| Moore & SON Bricklaying Ltd | Construction | 2025 |
| Moore Barlow LLP | | 2008 |
| Moore Blatch Limited | Professional & scientific | 1992 |
| Moore Blatch Resolve LLP | | 2008 |
| Moore Blatch Services Limited | Extraterritorial | 2010 |
| Moores Cleaning Services Limited | Administrative & support | 2001 |
| Moorland Views Limited | Construction | 2019 |
| Mordent Limited | Health & social care | 2015 |
| More House Surveys Ltd | Real estate | 2021 |