| Lumiere Kinesis Property Limited | Real estate | 2009 |
| Lumy Health Ltd | Wholesale & retail | 2026 |
| Luxury Modules Limited | Construction | 2024 |
| Lymphatic Therapy Solutions Ltd | Health & social care | 2020 |
| Lyndhurst Management 2014 Limited | Construction | 2014 |
| Lysander Court Limited | Households | 1984 |
| M & F Consultancy Ltd | Professional & scientific | 2003 |
| M & M Personal Vintners Ltd | Wholesale & retail | 2011 |
| M & S Burrows Limited | Wholesale & retail | 2022 |
| M and M Sparkle Clean Ltd | Administrative & support | 2025 |
| M G Build Limited | Construction | 2009 |
| M G Motor Tech Limited | Wholesale & retail | 2017 |
| M G Roofing Services Limited | Construction | 2011 |
| M Gould Construction Limited | Construction | 2006 |
| M Hardy Roofing Limited | Construction | 2021 |
| M J Print Limited | Administrative & support | 2005 |
| M J Recovery and Maintenance Ltd | Financial services | 2022 |
| M J Recovery Services Ltd | Transport & logistics | 2016 |
| M J Welding Services Limited | Construction | 2015 |
| M P Filtri (Property) Limited | Hospitality | 1996 |
| M P Filtri (UK) Limited | Manufacturing | 1987 |
| M&M Smart Repairs Ltd | Wholesale & retail | 2015 |
| M&Y Formwork Ltd | Construction | 2025 |
| M-Shana Ltd | Public administration | 2020 |
| M055 Property Limited | Real estate | 2023 |
| M8 Property Holding Ltd | Real estate | 2022 |
| M8B8 Ltd | Transport & logistics | 2022 |
| Magic Bees Ltd | Manufacturing | 2023 |
| Magic Spoon Caterers Limited | Hospitality | 2023 |
| Magic Square (UK) Technologies Limited | Information & communication | 2012 |
| Magnus Investment Holdings Ltd | Administrative & support | 2021 |
| Magpie (Manchester House) Limited | Wholesale & retail | 2000 |
| Mahal Kita Management Ltd | Administrative & support | 2016 |
| Mahalia Ltd | Wholesale & retail | 2025 |
| Mailtube Limited | Households | 1987 |
| Mainsport Ltd | Manufacturing | 1981 |
| MAJ Property Project Ltd | Real estate | 2021 |
| Makup Limited | Arts & recreation | 2014 |
| Maltings Court RTM Company Limited | Households | 2011 |
| Managed Offices.Biz Limited | Real estate | 2003 |
| Management and Risk Holdings Limited | Financial services | 2024 |
| Management and Risk Solutions Ltd | Professional & scientific | 2018 |
| Mandara Point Management Company Limited | Real estate | 2006 |
| Mannina Limited | Wholesale & retail | 2020 |
| Manor Farm Leisure Limited | Administrative & support | 2007 |
| Maple (181) Limited | Households | 2002 |
| Maple Heating Solutions Ltd | Construction | 2026 |
| Mapp Properties Management Limited | Construction | 2006 |
| Marcanne Limited | Real estate | 2024 |
| March Safety Solutions Ltd | Professional & scientific | 2019 |
| Marco Bille Physiotherapy Ltd | Health & social care | 2023 |
| Marius Gheorghe Transport Ltd | Transport & logistics | 2020 |
| Marius Grill Limited | Hospitality | 2023 |
| Mark a Jeffrey Limited | Construction | 2009 |
| Mark Hamer Plumbing & Heating Limited | Construction | 2011 |
| Mark Savage Associates Limited | Professional & scientific | 2012 |
| Marks Mews Management Company Limited | Households | 1999 |
| Marshall PUB Company Ltd | Hospitality | 2018 |
| Martin Jones Financial Planning Consultants LLP | | 2020 |
| MARTRANS24/7 Limited | Transport & logistics | 2024 |
| Marx 71 Limited | Professional & scientific | 2011 |
| Maschm Limited | Other services | 2016 |
| Mason 21 Holdings Limited | Financial services | 2018 |
| Mass Freehold Limited | Administrative & support | 2022 |
| Masters Saddles Limited | Wholesale & retail | 2022 |
| Matcha MI Limited | Manufacturing | 2025 |
| Matei Cirstea Ltd | Transport & logistics | 2020 |
| Matei&Ariana Ltd | Transport & logistics | 2025 |
| Mather Collectable Motor Cars Ltd | Wholesale & retail | 2013 |
| Mathi School of Dance Ltd | Arts & recreation | 2025 |
| Mathsplus Ltd | Education | 2023 |
| Matley Legal Limited | Administrative & support | 2020 |
| Matt Gotrel Performance Services Ltd | Arts & recreation | 2016 |
| Matthew-Manning Ltd | Households | 2021 |
| Matthumphreys Limited | Wholesale & retail | 2015 |
| Mattress & BED Store Limited | Wholesale & retail | 2001 |
| Maverick Consultancy Services Limited | Professional & scientific | 2026 |
| Maverick Foods Ltd | Professional & scientific | 2007 |
| Maverick Methods Ltd | Education | 2019 |
| Maverick Restaurants Limited | Hospitality | 2026 |
| MAX Braham Construction Ltd | Construction | 2021 |
| Maximal Computer Services Limited | Hospitality | 1993 |
| Mayfair Care Agency Limited | Health & social care | 2003 |
| Mayfair Foods Limited | Wholesale & retail | 1995 |
| Mayfair Park Estates Limited | Real estate | 2026 |
| Mayplace Management Company Limited | Hospitality | 1996 |
| Maypole Tax Solutions Ltd | Professional & scientific | 2011 |
| MC Haulage Ltd | Transport & logistics | 2018 |
| Mcconnel Limited | Manufacturing | 1935 |
| Mcgrath Construction Limited | Construction | 2015 |
| Mcgrath Property UK Limited | Real estate | 2021 |
| Mcinnes Communications Limited | Professional & scientific | 2005 |
| Mclean Aviation Consulting Ltd | Administrative & support | 2016 |
| MD Auto Repair 1 Ltd | Wholesale & retail | 2026 |
| MDB Tuition Limited | Education | 2014 |
| MDH Forestry Services Limited | Agriculture & fishing | 2010 |
| MDR Engineering Limited | Manufacturing | 1997 |
| Meadow View Waterside Management Company Limited | Households | 2021 |
| Meadows Management (Pillerton) Limited | Households | 2019 |
| Med-Pharma Consultancy Ltd | Professional & scientific | 2023 |