| Made in Marylebone Limited | Wholesale & retail | 2012 |
| Made in Sheffield Limited | Other services | 2012 |
| Made in Sicily Limited | Hospitality | 2024 |
| Made in the Cellar Ltd | Wholesale & retail | 2016 |
| Made Matcha Company Limited | Extraterritorial | 2025 |
| Made North Ltd | Information & communication | 2018 |
| Made Property and Development Ltd | Construction | 2025 |
| Made Simple Management Ltd | Professional & scientific | 2019 |
| Made YOU Look Beauty Ltd | Other services | 2026 |
| Madeitcomputers Ltd | Professional & scientific | 2018 |
| Madewa Health Care Limited | Health & social care | 2018 |
| Madewithpixels Ltd | Information & communication | 2013 |
| Madey Limited | Wholesale & retail | 2015 |
| Madhusri Limited | Wholesale & retail | 2023 |
| Madina Business Consulting Limited | Information & communication | 2025 |
| Madina Catering Yorkshire Limited | Hospitality | 2021 |
| Madina Fruit and VEG Ltd | Wholesale & retail | 2026 |
| MADINA786 Ltd | Hospitality | 2026 |
| Madley FAR Limited | Financial services | 2023 |
| Madorie Ltd | Real estate | 2024 |
| Madras Food Ltd | Hospitality | 2025 |
| Madvic Logistics Ltd | Transport & logistics | 2025 |
| Madwell & Co Investments Ltd | Professional & scientific | 2023 |
| Madynno Ltd | Health & social care | 2021 |
| Maeve Atelier Ltd | Wholesale & retail | 2025 |
| MAF Properties ( UK ) Limited | Extraterritorial | 2018 |
| Mafro Music Limited | Information & communication | 2021 |
| Mafya Properties Ltd | Real estate | 2020 |
| MAG &Ulas Limited | Administrative & support | 2022 |
| MAG Environmental Limited | Water & waste | 2021 |
| MAG Finance Limited | Professional & scientific | 2017 |
| MAG Motor Services Limited | Wholesale & retail | 2019 |
| MAG Orthotics Limited | Manufacturing | 2004 |
| Mag-Bor Ltd | Manufacturing | 2021 |
| Mage Supplements Limited | Professional & scientific | 2023 |
| Maggi Properties LLP | | 2016 |
| Maggiebell Inn Ltd | Hospitality | 2025 |
| Magic Business Services Ltd | Professional & scientific | 2006 |
| Magic Cote Limited | Wholesale & retail | 2004 |
| Magic of India Ltd | Hospitality | 2026 |
| Magic Quid Limited | Administrative & support | 2001 |
| Magical Adventures Group Ltd | Education | 2026 |
| Magical Memories Limited | Wholesale & retail | 2023 |
| Magielog Limited | Wholesale & retail | 2019 |
| Magna Parva Lifts Limited | Construction | 2018 |
| Magna Technology Group Ltd. | Information & communication | 2013 |
| Magnet Properties Ltd | Real estate | 2025 |
| Magnetic Rubber Direct Limited | Extraterritorial | 2021 |
| Magnetic Solutions Limited | Manufacturing | 2005 |
| Magnolia Bidco Limited | Financial services | 2024 |
| Magnolia Court (Sheffield) Limited | Households | 1989 |
| Magnolia Midco Limited | Financial services | 2024 |
| Magnolia Topco Limited | Financial services | 2024 |
| Magnomatics Limited | Professional & scientific | 2006 |
| Magnosphere UK Limited | Wholesale & retail | 2023 |
| Magnotone Limited | Other services | 2014 |
| Magnus Accountants Limited | Professional & scientific | 2015 |
| Magnus Group Holdings Ltd | Financial services | 2025 |
| Magnus Trading Ltd | Wholesale & retail | 2026 |
| Maguire Media Limited | Information & communication | 2025 |
| Mahad Consults Ltd | Information & communication | 2025 |
| Mahad Logistics Limited | Transport & logistics | 2025 |
| Maham Medical Services Ltd | Health & social care | 2014 |
| Mahamba Services Limited | Health & social care | 2014 |
| Mahasathya Private Company Ltd | Health & social care | 2025 |
| Maher Limited | Manufacturing | 1952 |
| Mahima a Ltd | Health & social care | 2022 |
| MAI Software Limited | Information & communication | 2025 |
| Maiamax Limited | Professional & scientific | 2013 |
| Maiandros Consulting Ltd | Wholesale & retail | 2017 |
| Maiblu Sports Ltd | Wholesale & retail | 2025 |
| Maid in Stannington Limited | Administrative & support | 2023 |
| Maid in Yorkshire Ltd | Administrative & support | 2021 |
| Maid to Impress Ltd | Administrative & support | 2024 |
| Maidglen Limited | Real estate | 1995 |
| Mailey Cafe Ltd | Hospitality | 2021 |
| Maillard Ltd | Health & social care | 2023 |
| Main Door Investments Ltd | Real estate | 2019 |
| Main Electrical Ltd | Construction | 1998 |
| Main Interest Limited | Hospitality | 2020 |
| Main Story Limited | Wholesale & retail | 2018 |
| Main Street Vapes Ltd | Wholesale & retail | 2025 |
| Main-Board Consultancy Limited | Extraterritorial | 2015 |
| Maine 24 Limited | Administrative & support | 2013 |
| Mainline Marketing U K. Limited | Wholesale & retail | 1983 |
| Mainostie Limited | Professional & scientific | 2015 |
| Mainstack Group Ltd | Information & communication | 2026 |
| Mainstack Holdings Limited | Financial services | 2026 |
| Mainstay Mart Ltd | Information & communication | 2023 |
| Maintech Power Services Limited | Manufacturing | 2011 |
| Maintenance Plus Ltd | Other services | 2025 |
| Maintenance Properties Limited | Real estate | 2016 |
| Maison DE Buns Limited | Hospitality | 2025 |
| Maison DE Burger’S Ltd | Hospitality | 2022 |
| Maison DE Carat Ltd | Manufacturing | 2025 |
| Maison DE Vauclaire Ltd | Wholesale & retail | 2026 |
| Maison DU Biere (Stocksbridge) Limited | Wholesale & retail | 2021 |
| Maison Grassi Kikuchi Limited | Professional & scientific | 2019 |
| Maison JO Ltd | Manufacturing | 2025 |
| Maison ZEE Limited | Wholesale & retail | 2022 |