| Matisrot Limited | Information & communication | 2015 |
| Matrioska Ltd | Wholesale & retail | 2020 |
| Matt Bridge Ltd | Professional & scientific | 2010 |
| Matt White Estates Limited | Households | 2018 |
| Matt White Limited | Information & communication | 2004 |
| Matthew Beedle Photography Ltd | Professional & scientific | 2017 |
| Matthew Blake Ltd | Arts & recreation | 2008 |
| Matthew Eluwande Limited | Manufacturing | 2024 |
| Matthew King Ltd | Professional & scientific | 2022 |
| Maunder Construction & Consultancy Limited | Administrative & support | 2024 |
| Mauray Properties Limited | Real estate | 2019 |
| Mauray Securities Limited | Financial services | 2025 |
| Mauve Consultants Limited | Administrative & support | 2015 |
| Mauve Holdings Limited | Households | 2020 |
| Mavenly Ltd | Professional & scientific | 2024 |
| Mavin Training Limited | Professional & scientific | 2002 |
| Mavs Investments Ltd | Real estate | 2024 |
| MAX Air Air Conditioning Ltd | Construction | 2024 |
| MAX Michelson Limited | Wholesale & retail | 2017 |
| Maxander Sport Ltd | Arts & recreation | 2021 |
| Maxify Health & Protection Limited | Administrative & support | 2024 |
| Maxika Homes (Construction) Ltd | Real estate | 2022 |
| Maxika Homes (Eastbourne) Limited | Real estate | 2021 |
| Maxika Homes (Ottershaw) Ltd | Real estate | 2021 |
| Maxika Homes (Westward) Ltd | Real estate | 2021 |
| Maxika Homes (WESTWARD2) Ltd | Real estate | 2022 |
| Maxika Homes Ltd | Real estate | 2018 |
| Maximos Solutions Ltd | Construction | 2026 |
| Maximus Web Development Limited | Information & communication | 2015 |
| Maxine Edney Associates Ltd | Professional & scientific | 2013 |
| Maxson Ltd | Construction | 2018 |
| Maxwell House(Palmerston Road)Management Company Limited | Households | 1965 |
| Maxwells Garden Services Limited | Administrative & support | 2026 |
| Maxwelton House Property Company Limited | Real estate | 1973 |
| Maxxbuild Ltd | Construction | 2023 |
| Maxxilia Hair Salon Ltd | Other services | 2018 |
| Maya AI Ltd | Information & communication | 2025 |
| Mayair Limited | Real estate | 1998 |
| Mayfair Asset Management Ltd | Other services | 2021 |
| Mayfair Finance Limited | Wholesale & retail | 2015 |
| Mayfair Hard Disk Recovery Limited | Information & communication | 2016 |
| Mayfair Maharaja Ltd | Information & communication | 2023 |
| Mayfair Resources Ltd | Administrative & support | 2018 |
| Mayfair Search Group Ltd | Administrative & support | 2011 |
| Mayflower Electrical Limited | Information & communication | 2012 |
| Maynetrees Property Limited | Real estate | 2020 |
| Mayotta Limited | Information & communication | 2022 |
| Mays Kebab Ltd | Hospitality | 2025 |
| Mays Lane OFF Licence Limited | Wholesale & retail | 2023 |
| Mays Property Services Ltd | Real estate | 2025 |
| Mays Way Ltd | Construction | 2009 |
| Mayura Foods Limited | Wholesale & retail | 2026 |
| Maze Collections Limited | Administrative & support | 2010 |
| MB Group Investments Ltd | Real estate | 2026 |
| MB Investment and Training Ltd | Administrative & support | 2021 |
| MBL Education Limited | Education | 2020 |
| MBS Law Ltd | Professional & scientific | 2025 |
| MC Print Management Services Limited | Manufacturing | 2023 |
| MC Private Finance Limited | Financial services | 2020 |
| MCB Trading Co Ltd | Wholesale & retail | 2025 |
| Mccourts Construction Ltd | Construction | 2019 |
| Mcdoherty Property Ltd | Real estate | 2022 |
| Mcdonnell Mohan Limited | Real estate | 1979 |
| Mcewan & Penford Ltd | Administrative & support | 2005 |
| Mcfarm Limited | Administrative & support | 2024 |
| Mcginley Family Charitable Trust | Financial services | 2017 |
| Mcginley Group Limited | Professional & scientific | 2009 |
| Mcginley Management Limited | Real estate | 1997 |
| Mcginley New Co. 1 Ltd | Real estate | 2017 |
| Mcginley New Co. 2 Limited | Real estate | 2011 |
| Mcginley New Co. 3 Ltd | Real estate | 2017 |
| Mcginley New Co. 4 Ltd | Real estate | 2017 |
| Mcginley New Co. 5 Ltd | Real estate | 2017 |
| Mclaren Resourcing LLP | | 2013 |
| MCM Property Investments Limited | Real estate | 2022 |
| Mcmss Limited | Real estate | 2014 |
| Mcneil Gilson Ltd | Health & social care | 2022 |
| Mcqueen International Limited | Information & communication | 2024 |
| Mcwright and Dodd Ltd | Extraterritorial | 2016 |
| MD Golf Consultancy Limited | Professional & scientific | 2020 |
| MD M and E Services Ltd | Information & communication | 2019 |
| MD Nakadi Planning Limited | Construction | 2017 |
| MDF Tuition Ltd | Education | 2025 |
| MDM Heating & Plumbing Ltd | Construction | 2013 |
| MDM Maintenance Ltd | Construction | 2019 |
| MDM Property Investment Ltd | Real estate | 2025 |
| MDO Property Development Limited | Construction | 2017 |
| MDO Property Ltd | Real estate | 2019 |
| Mdsw Property Services Limited | Real estate | 2024 |
| ME Healthy Living H&L Ltd | Wholesale & retail | 2009 |
| ME10 Football Limited | Arts & recreation | 2024 |
| Mead Energy & Architectural Design Ltd | Professional & scientific | 2014 |
| Meadow Court Belle VUE Lane Residents Association Limited | Households | 1994 |
| Meadway Estates (London) Limited | Real estate | 2025 |
| Meadway Marketing Limited | Professional & scientific | 2024 |
| Meak Properties Ltd | Real estate | 2026 |
| Meal Prep Group Ltd | Hospitality | 2025 |
| Meancat Holdings Ltd | Financial services | 2021 |
| Meancat Ltd | Real estate | 2020 |
| Mear Professional Services Limited | Professional & scientific | 2022 |