| Matt Bentley-Viney Ltd | Information & communication | 2019 |
| Matthew Hayter Limited | Information & communication | 2025 |
| Mattjon Limited | Professional & scientific | 2004 |
| Mays (Bournemouth) Limited | Extraterritorial | 2009 |
| Mccomish Insurance Brokers Limited | Financial services | 2010 |
| Mchouston Holdings Ltd | Real estate | 2025 |
| Mchouston Properties Limited | Real estate | 2017 |
| Mckinlays Bournemouth Sales Limited | Real estate | 2014 |
| Mctv Freehold Management Limited | Households | 2011 |
| Meade Ltd | Professional & scientific | 2014 |
| Meadow View (Winchester) Limited | Households | 2022 |
| Meadowfield Holdings Limited | Professional & scientific | 2002 |
| Meerkat Accounting Limited | Professional & scientific | 2011 |
| Meineck Investments Ltd | Real estate | 2024 |
| Meisy Ltd | Education | 2025 |
| Melbury House Limited | Professional & scientific | 1993 |
| Melford Property Services Ltd | Real estate | 2025 |
| Melville Gardens Limited | Real estate | 2025 |
| Melvin Services Limited | Administrative & support | 2018 |
| Memofield Limited | Real estate | 1983 |
| MEP South Developments Ltd | Construction | 2025 |
| Meriton Personal Executors Ltd | Professional & scientific | 2010 |
| MGD 2025 Limited | Real estate | 2023 |
| MGS Maintenance Limited | Real estate | 2015 |
| MH Dept South Limited | Manufacturing | 2017 |
| Michelle East Ltd | Professional & scientific | 2019 |
| Micromacro Solutions Ltd | Wholesale & retail | 2024 |
| Midhaven Holdings Limited | Financial services | 2015 |
| Midhaven Investments Limited | Real estate | 2015 |
| Mike Hancock Holdings | Financial services | 2018 |
| Mike Peasland Consulting Ltd | Professional & scientific | 2014 |
| Milestone Managed Print Services Ltd | Manufacturing | 2022 |
| Millington Family Investments Ltd | Real estate | 2020 |
| Milsom Insurance Brokers LLP | | 2019 |
| Mini Munchkins Day Nursery Ltd | Education | 2018 |
| Mini Soccer Advance Limited | Other services | 2018 |
| Mint Property Surveyors Ltd | Construction | 2023 |
| Mirus Ceramics Limited | Construction | 2008 |
| Miss Amelia Rose Limited | Wholesale & retail | 2016 |
| Misschief Collections Limited | Wholesale & retail | 2018 |
| Mitchell Smith Ltd | Extraterritorial | 2024 |
| MIX IT UP Competitions Ltd | Administrative & support | 2024 |
| MJB Entertainment Limited | Arts & recreation | 2014 |
| MJH House Clearance & Property Services Limited | Other services | 2019 |
| MJK Professional Limited | Professional & scientific | 2014 |
| Mjoc-Nms Holdings Limited | Financial services | 2017 |
| MKR Digital Ltd | Professional & scientific | 2015 |
| ML Bowles Electrical Services Limited | Manufacturing | 2016 |
| MLG Construction Consultancy Ltd | Construction | 2025 |
| MMF Cars Ltd | Transport & logistics | 2025 |
| Mmjf Developments Ltd | Construction | 2026 |
| MMT Developments Ltd | Construction | 2013 |
| Modify Medical Aesthetics Ltd | Other services | 2022 |
| Mohc Ltd | Information & communication | 2001 |
| Momentum Risk Solutions UK Limited | Financial services | 2024 |
| Momentum Tuning Ltd | Wholesale & retail | 2020 |
| Mondiki Enterprises Ltd | Professional & scientific | 2022 |
| Money Saving Energy Limited | Energy | 2020 |
| Moneyback Ltd | Other services | 2012 |
| Monforte Limited | Real estate | 2018 |
| Monmar Limited | Households | 2013 |
| Moon Properties (South) Ltd | Real estate | 2022 |
| Moore Investment Properties Ltd | Real estate | 2024 |
| Moorhaven Flats (Management) Limited | Households | 1976 |
| Morgan Design & Construction Ltd | Construction | 2018 |
| Mortgage and Protection Advice Services Limited | Financial services | 2020 |
| Mount Lake (IOW) Ltd | Real estate | 2023 |
| Moya Limited | Professional & scientific | 2018 |
| MP Bridges Limited | Professional & scientific | 1991 |
| MPT UK Consulting Limited | Information & communication | 2018 |
| MRD Bikes Limited | Professional & scientific | 2021 |
| MRF Consulting Ltd | Financial services | 2013 |
| MRS Pott's Catering Ltd | Hospitality | 2019 |
| MT Homes South Limited | Construction | 2012 |
| Mtech Appliances Limited | Financial services | 2019 |
| Mullender Wealth Management Ltd | Professional & scientific | 2026 |
| Multi Heating Services Limited | Construction | 2019 |
| Mumfluence.Co Ltd | Professional & scientific | 2023 |
| Munchkins Soft Play Ltd | Extraterritorial | 2024 |
| Musicalink Ltd | Education | 2022 |
| My AI Ltd | Other services | 2024 |
| My Healing Harmony Ltd | Wholesale & retail | 2020 |
| N LEE Steel Services Ltd | Construction | 2021 |
| N.O.D. Mortgages Ltd | Financial services | 2025 |
| Namco Travel Ltd | Wholesale & retail | 2022 |
| Nana's Kitchen Ltd | Manufacturing | 2020 |
| NAP Electrical Ltd | Construction | 2011 |
| Nautical Wind Ltd | Construction | 2017 |
| NCT Lift Controls Ltd | Manufacturing | 2025 |
| Neil Stevens Limited | Construction | 2013 |
| Neil Wood Limited | Professional & scientific | 2010 |
| Nesw Commercial Cleaning Limited | Administrative & support | 2024 |
| Nesw Construction Ltd | Construction | 2024 |
| Nesw Ltd | Construction | 2021 |
| New Forest Construction and Landscaping Ltd | Construction | 2015 |
| New GEN Renewables Ltd | Construction | 2024 |
| New Golden CUT Ltd | Other services | 2025 |
| Newlook Landscaping & Driveways Ltd | Construction | 2014 |
| NEWSNO1 Limited | Wholesale & retail | 2018 |
| Nginuity Avionics & Electronics Ltd | Manufacturing | 2016 |