| Martin Bailey Consulting Ltd | Other services | 2023 |
| Martin Lauren International Limited | Manufacturing | 2021 |
| Marvel World Limited | Wholesale & retail | 2021 |
| Marvellous Care Limited | Professional & scientific | 2008 |
| Marvellous Credit Limited | Professional & scientific | 2006 |
| Marvellous Energy Limited | Other services | 2020 |
| Marvellous Holdings Limited | Professional & scientific | 2004 |
| Marvellous Properties Limited | Real estate | 2004 |
| Marvellous UK Limited | Administrative & support | 2003 |
| Mary Alice Limited | Information & communication | 2010 |
| Mary Productions Ltd | Information & communication | 2019 |
| Maryo Solutions Ltd | Manufacturing | 2024 |
| MAS Studio Limited | Information & communication | 2016 |
| Mas-Houseware Industry Co., Limited | Extraterritorial | 2021 |
| Masa International Logistics Co., Ltd | Wholesale & retail | 2022 |
| Masaba Trading Ltd. | Wholesale & retail | 2023 |
| Mascci Intelligent Technology Co., Ltd. | Wholesale & retail | 2021 |
| Masgd Ltd | Extraterritorial | 2019 |
| Mass Consultancy Services Ltd | Professional & scientific | 2026 |
| Mass Industrial Limited | Manufacturing | 2022 |
| Massa Investments Limited | Real estate | 2018 |
| Mastars Motion Plastic Co., Ltd | Manufacturing | 2024 |
| Master Cutters Hayes Limited | Other services | 2014 |
| Master Marine Supply Co., Ltd | Manufacturing | 2023 |
| Master Process Limited | Wholesale & retail | 2021 |
| Master Property Maintenance Limited | Construction | 2024 |
| Masterfilte Limited | Extraterritorial | 2019 |
| Mastiff Oilfield Services Ltd. | Extraterritorial | 2020 |
| Mastins Property Services Limited | Extraterritorial | 2023 |
| Mastros Landlords LLP | | 2022 |
| Maswe Decor Materials Co., Ltd | Extraterritorial | 2022 |
| MAT & Co Accountancy Services Limited | Professional & scientific | 2003 |
| Mat-E Construction Ltd | Construction | 2023 |
| Match International Limited | Extraterritorial | 2020 |
| Matchicare Group International Ltd. | Extraterritorial | 2019 |
| Matchspace Limited | Arts & recreation | 2020 |
| Matchspace Padel Limited | Arts & recreation | 2026 |
| Matchstack Ltd | Information & communication | 2021 |
| Maten Industrial&Trading Co., Ltd | Wholesale & retail | 2012 |
| Mathelen Ltd | Administrative & support | 2018 |
| Maths Partnership Holdings Ltd | Financial services | 2023 |
| Maths Partnership Limited | Professional & scientific | 1993 |
| Matrisn Enterprises, Ltd. | Manufacturing | 2024 |
| Matt George Wigs Limited | Other services | 2019 |
| Matt Holdings Limited | Real estate | 2016 |
| Matt White TV Limited | Information & communication | 2013 |
| Matt's Renovations Limited | Construction | 2021 |
| Maverick Crude Ltd | Mining & quarrying | 2026 |
| Maverickmind Co., Ltd | Wholesale & retail | 2023 |
| Mavis Freehold Limited | Real estate | 2024 |
| Mawson Holding Group Co., Ltd | Manufacturing | 2024 |
| MAX & MIA Bath Co. Limited | Wholesale & retail | 2021 |
| MAX Chain Hoist Co., Ltd. | Extraterritorial | 2012 |
| MAX Import and Export Co., Ltd | Extraterritorial | 2021 |
| MAX Power Creation Ltd | Professional & scientific | 2021 |
| MAX Speed Tuning Technology Limited | Wholesale & retail | 2021 |
| MAX Wish Co., Ltd | Extraterritorial | 2016 |
| Maxcare Industrial Co., Ltd | Extraterritorial | 2023 |
| Maxconn Marine Service Co., Ltd | Extraterritorial | 2019 |
| Maxfit Sports Co., Ltd | Arts & recreation | 2023 |
| Maxi Light Brand Management (UK) Co., Ltd. | Agriculture & fishing | 2025 |
| Maxline Corporation Limited | Extraterritorial | 2018 |
| Maxmany Enterprise Co., Ltd. | Manufacturing | 2023 |
| Maxmov Limited | Extraterritorial | 2018 |
| Maxocean Engineering Co., Ltd | Extraterritorial | 2019 |
| Maxport Supply Ltd | Wholesale & retail | 2025 |
| Maxrun Industrial Co., Ltd. | Extraterritorial | 2011 |
| Maxstar Group Limited | Wholesale & retail | 2026 |
| Maxtop Furniture Co., Ltd | Extraterritorial | 2014 |
| Maxway Machine Company Ltd. | Wholesale & retail | 2016 |
| MAY Sun Import and Export Co., Ltd | Wholesale & retail | 2022 |
| May's Hill Advisory Limited | Financial services | 2010 |
| Maya Mckeever Limited | Information & communication | 2020 |
| Mayday Management Services Limited | Professional & scientific | 1996 |
| Mayfair Road Ltd | Real estate | 2018 |
| Mayfield Dental Limited | Health & social care | 2012 |
| Mayfield Lodge Limited | Households | 2003 |
| Mayhome International Trade Co., Ltd | Wholesale & retail | 2024 |
| Mayler Trading Limited | Professional & scientific | 2015 |
| Maylerescape Limited | Wholesale & retail | 2021 |
| Maylinda Limited | Wholesale & retail | 2023 |
| Maynos Consulting Limited | Wholesale & retail | 2022 |
| Mayrine Properties Limited | Real estate | 2017 |
| Maywood Estates Limited | Real estate | 2016 |
| Mazbridge Property Ltd | Households | 2025 |
| Mazo Beck Limited | Real estate | 2021 |
| MBI Global (China) Ltd | Extraterritorial | 2016 |
| MBM Interiors Ltd | Construction | 2023 |
| Mbrs Consultancy Limited | Professional & scientific | 2017 |
| Mbxtech Limited | Extraterritorial | 2016 |
| MC International Trade Ltd | Extraterritorial | 2021 |
| Mcchaps Holdings Ltd | Real estate | 2020 |
| Mcdermott Business Consultancy Limited | Professional & scientific | 2001 |
| Mcgrego Ltd | Hospitality | 2026 |
| Mckinson Solutions Limited | Professional & scientific | 2024 |
| Mclantis Group International Limited | Extraterritorial | 2010 |
| Mclaren International Holdings Limited | Extraterritorial | 2020 |
| Mclaren Pullan Limited | Real estate | 2016 |
| MCN Exchange Services Ltd | Financial services | 2026 |
| MCS Tech Co., Ltd | Manufacturing | 2025 |