| MG Training Solutions Ltd | Education | 2005 |
| Mghc Ltd | Professional & scientific | 2022 |
| MGM Solutions Ltd | Construction | 2022 |
| MH Joinery & General Building Limited | Extraterritorial | 2019 |
| MH Joinery (Oxford) Limited | Extraterritorial | 2019 |
| MH Skips Limited | Water & waste | 2019 |
| MH Tyres Bath Ltd | Wholesale & retail | 2021 |
| MHL Bidco Limited | Financial services | 2023 |
| MHL Midco Limited | Financial services | 2023 |
| MHL Topco Limited | Financial services | 2023 |
| Miami Heat Ltd | Wholesale & retail | 2014 |
| Mianhua Consulting Limited | Professional & scientific | 2021 |
| Micah Law Occupational Therapy Ltd | Health & social care | 2020 |
| Michael Sellars Limited | Arts & recreation | 2015 |
| Michael Wackett & Co Ltd | Manufacturing | 1998 |
| Michael Wright Photography Limited | Professional & scientific | 2025 |
| Michelle Parr Limited | Administrative & support | 2006 |
| Mickledore Consulting Ltd | Information & communication | 2009 |
| Microdesigns Limited | Wholesale & retail | 2020 |
| Midas Close Protection Ltd | Administrative & support | 2024 |
| Midash Limited | Professional & scientific | 2019 |
| Middle Ground Growers C.I.C. | Agriculture & fishing | 2021 |
| Midfoils Tech Ltd | Information & communication | 2007 |
| Midford Books Limited | Wholesale & retail | 2024 |
| Midlands Derm Defined Ltd | Health & social care | 2025 |
| Midsomer Priory Limited | Hospitality | 2012 |
| Mighty Splash Swim School Ltd | Administrative & support | 2011 |
| Mightysighty Ltd | Information & communication | 2024 |
| Mike Carling Limited | Information & communication | 2007 |
| Mike Crockford Test Pilot Ltd | Professional & scientific | 2026 |
| Mike&Mayatradingaslamaya Ltd | Hospitality | 2019 |
| Milano International Holdings Limited | Professional & scientific | 2019 |
| Miles House Owners Ltd | Extraterritorial | 2022 |
| Mileson-Stigter Consultancy & Coaching Ltd | Professional & scientific | 2020 |
| Milestone Publishing Limited | Information & communication | 2007 |
| Milk BUN Deli Ltd | Hospitality | 2023 |
| Milk Street Group Ltd | Information & communication | 2026 |
| Mill House Roofing Limited | Construction | 1987 |
| Millar Advisory Services Ltd | Professional & scientific | 2022 |
| Millbrook Court Bath Management Limited | Households | 1998 |
| Millenium Court Limited | Real estate | 2011 |
| Millenium Properties Batheaston Limited | Construction | 2016 |
| Millennium Homes Management Limited | Real estate | 2024 |
| Millennium House 1 Beckford Road Bath (Management Company) Limited | Extraterritorial | 2017 |
| Millennium Rise Management Company Limited | Households | 2022 |
| Millennium Terrace Management Company Limited | Households | 2022 |
| Miller & Eanes Property Solutions Ltd | Households | 2020 |
| Miller Walk (Bathampton) Management Limited | Real estate | 1995 |
| Millies Care and Support Agency Limited | Other services | 2012 |
| Milne Plumbing & Heating Services Limited | Construction | 2008 |
| Milne Turner Developments Ltd | Real estate | 2021 |
| MIN of DES Limited | Information & communication | 2011 |
| Mind&Me Ltd | Education | 2024 |
| Mindforge Ltd | Information & communication | 2021 |
| Mindful Technology Limited | Information & communication | 2017 |
| Mindmorph Ltd | Professional & scientific | 2025 |
| Minerva Art Supplies Limited | Wholesale & retail | 2014 |
| Minerva's Fairies Limited | Transport & logistics | 2017 |
| Mini Marvel Limited | Administrative & support | 2005 |
| Mini Mermaid Tails Ltd | Wholesale & retail | 2022 |
| Minim ROW Ltd | Professional & scientific | 2018 |
| Mining Commodities Limited | Wholesale & retail | 2002 |
| Minster Square Limited | Construction | 1994 |
| Mint Business Solutions Limited | Professional & scientific | 2000 |
| Mint Cake Productions Ltd | Information & communication | 2019 |
| Mint Source Productions Limited | Information & communication | 2016 |
| Mipad Bath Ltd | Real estate | 2017 |
| Mirror Mirror Design & Retouching Limited | Professional & scientific | 2011 |
| Misper Investments Ltd | Construction | 2023 |
| Misri Ltd | Professional & scientific | 2025 |
| Miss Leading Limited | Information & communication | 2025 |
| Mission Critical Applications Limited | Information & communication | 1999 |
| Mitcham Consulting Limited | Professional & scientific | 2012 |
| Mitchell Creative Group Ltd | Professional & scientific | 2019 |
| Mitchell Eley Gould Limited | Professional & scientific | 2002 |
| Mitos Global Limited | Education | 2021 |
| Mizu Limited | Information & communication | 2000 |
| MJ Recruitment Ltd | Administrative & support | 2018 |
| MJC 2FLYING Ltd | Transport & logistics | 2018 |
| MJC Electromech Limited | Professional & scientific | 2016 |
| MJF Plumbing & Heating Ltd | Construction | 2022 |
| MJG Trading Ltd | Wholesale & retail | 2025 |
| MJL Motion Ltd | Information & communication | 2024 |
| Mjmundy Consulting Ltd | Professional & scientific | 2025 |
| Mjolk Limited | Hospitality | 2025 |
| Mjsi Plumbing & Property Management Ltd | Construction | 2023 |
| MJW Architects Limited | Professional & scientific | 2001 |
| MK Advice Ltd | Professional & scientific | 2023 |
| MK Beauty Bath Ltd | Other services | 2016 |
| MK Property (Twerton) Ltd | Real estate | 2024 |
| MK Retail (Twerton) Ltd | Wholesale & retail | 2025 |
| ML Living (UK) Ltd | Wholesale & retail | 2017 |
| Mlsglobaltech Limited | Professional & scientific | 2010 |
| MMJ Containers Limited | Transport & logistics | 2023 |
| MMP Bath Limited | Administrative & support | 2006 |
| MNS (Bristol) Limited | Wholesale & retail | 2016 |
| MO and K Limited | Real estate | 2024 |
| MOA and KIN Ltd | Real estate | 2020 |
| Mobius Binary Ltd | Professional & scientific | 2022 |
| Mobius International Holdings Limited | Financial services | 2021 |