| Maier Partnership Limited | Professional & scientific | 1998 |
| Maif Healthcare Ltd | Health & social care | 2023 |
| Main Source Ltd | Wholesale & retail | 2016 |
| Mainbridge Limited | Wholesale & retail | 1995 |
| Mainland Construction Engineering Ltd | Professional & scientific | 2021 |
| Mainline Control Ltd | Professional & scientific | 2007 |
| Mainsheet Consulting Limited | Professional & scientific | 2013 |
| Mainstay IT Limited | Information & communication | 2025 |
| Maintain Reliability Ltd | Professional & scientific | 2017 |
| Maintenance & Removal H&F Ltd | Construction | 2022 |
| Maintenance Work Management Ltd | Professional & scientific | 2018 |
| Maisie’S Worlingworth Ltd | Other services | 2024 |
| Maison Faune Ltd | Wholesale & retail | 2025 |
| Maison Fine Art Limited | Arts & recreation | 2026 |
| Maison Lisette Ltd | Professional & scientific | 2025 |
| Maison Margaux Limited | Hospitality | 2019 |
| Maithili UK Ltd | Wholesale & retail | 2024 |
| Majarira Ltd | Transport & logistics | 2015 |
| MAK Halal (Alumrock) Ltd | Hospitality | 2020 |
| MAK London Ltd | Professional & scientific | 2017 |
| MAK Southsea Limited | Hospitality | 2017 |
| Make IT Clear Group Limited | Financial services | 2018 |
| Make IT Count (Accountancy Services) Ltd | Professional & scientific | 2009 |
| Make IT Happen Planning Ltd | Professional & scientific | 2025 |
| Make IT Move Productions Ltd | Information & communication | 2016 |
| Make My House Home Limited | Wholesale & retail | 2015 |
| Make Productions Limited | Information & communication | 2005 |
| Makedau Limited | Transport & logistics | 2019 |
| Makers House Ltd | Wholesale & retail | 2018 |
| Makesoft Limited | Information & communication | 2012 |
| Makhado Limited | Administrative & support | 2019 |
| Makonza Sukutayi Holdings Limited | Agriculture & fishing | 2022 |
| MAL Limited | Professional & scientific | 1981 |
| Mala and Co Norwich Limited | Hospitality | 2016 |
| Malachite Bidco Limited | Financial services | 2024 |
| Malachite Midco Limited | Financial services | 2024 |
| Malachite Topco Limited | Financial services | 2024 |
| Malaya Blue Music Ltd | Extraterritorial | 2017 |
| Malbear Ltd | Information & communication | 2018 |
| Malber Limited | Real estate | 2004 |
| Malbern Investments Ltd | Financial services | 2026 |
| Malcor Estates Limited | Real estate | 2001 |
| Malden MAP Ltd | Real estate | 2024 |
| Maldon Mixes Limited | Manufacturing | 2020 |
| Malik MAC Ltd | Hospitality | 2020 |
| Malik Medicare Limited | Health & social care | 2006 |
| Malik Metal Work Limited | Manufacturing | 2009 |
| Malik's Restaurant LYE Ltd | Hospitality | 2017 |
| Mallery Ltd | Wholesale & retail | 2025 |
| Mallett Properties Ltd | Real estate | 2020 |
| Mallory Road Ltd | Administrative & support | 2022 |
| Malmains & Company Limited | Real estate | 2006 |
| Malni Chora Ltd | Hospitality | 2026 |
| Malone Flooring Ltd | Construction | 2021 |
| Malonemily Ltd | Arts & recreation | 2026 |
| Mals Cars Wymondham Limited | Wholesale & retail | 2021 |
| Maltby Plastering Limited | Construction | 2019 |
| Maltese Cross Dental Limited | Health & social care | 2023 |
| Malthousepubsgroup Ltd | Hospitality | 2025 |
| Maltsters Public House Ltd | Hospitality | 2024 |
| Malva Belle Ltd | Wholesale & retail | 2022 |
| Malzy Court Residents Association Limited | Households | 1994 |
| MAM Mortgages Ltd | Financial services | 2021 |
| Mama Beni Ltd | Hospitality | 2022 |
| Mama MIA Pizza D Ltd | Hospitality | 2026 |
| Mama SLY Foods Ltd | Manufacturing | 2025 |
| MAN Alive Theatre CIC | Health & social care | 2023 |
| Mana Contemporary Ltd | Wholesale & retail | 2022 |
| Manaca Limited | Health & social care | 2012 |
| Management Security Solutions Limited | Administrative & support | 2006 |
| Manaia-Koru Realty Limited | Information & communication | 2008 |
| Manchester Data Centres Limited | Real estate | 2026 |
| Mancroft Advice Project (MAP) | Health & social care | 2004 |
| Mancroft International Limited | Professional & scientific | 2008 |
| Mandalay Wellbeing CIC | Health & social care | 2017 |
| Mandalyn Hair Ltd | Other services | 2024 |
| Mandalyn Properties Ltd | Real estate | 2025 |
| Mandarin Cycles Limited | Wholesale & retail | 2011 |
| Mander Auctioneers and Valuers of Norwich Ltd | Wholesale & retail | 2024 |
| Mandji Bake Ltd | Manufacturing | 2021 |
| Manfaat Kitchen Ltd | Real estate | 2023 |
| Manfield Property Solutions Ltd | Administrative & support | 2015 |
| Mangal 1 Limited | Hospitality | 2022 |
| Mango -T Ltd | Hospitality | 2018 |
| Mango Online Learning Development Solutions Limited | Information & communication | 2021 |
| Mangoemoney Limited | Education | 2025 |
| Mangreen Trust | Health & social care | 1987 |
| Manley & Pitcher Construction Limited | Construction | 2006 |
| Mann & Co Plumbing and Heating Limited | Construction | 2026 |
| Mann Online Ltd | Wholesale & retail | 2025 |
| Mannah Properties Ltd | Real estate | 2017 |
| Manni's Takeaways Limited | Hospitality | 2017 |
| Manning Building Limited | Construction | 2025 |
| Manning Financial Services Limited | Financial services | 2013 |
| Mannington Hall Camping Limited | Administrative & support | 2017 |
| Mannix Sibanda and Sons Limited | Health & social care | 2011 |
| Mannpower Motorsport LLP | | 2018 |
| Manor Barn Holdings Ltd | Financial services | 2019 |
| Manor Commissioning Ltd | Information & communication | 2011 |
| Manor Court (Aylsham) Limited | Households | 1988 |