| Maniol Ltd | Wholesale & retail | 2025 |
| Maniza Ltd | Real estate | 2025 |
| Manjit SINGH1 Ltd | Construction | 2019 |
| Mankaran Limited | Wholesale & retail | 2017 |
| Mankey Ltd | Professional & scientific | 2026 |
| Manko Building Developments Limited | Wholesale & retail | 2008 |
| Mann Williams (Cardiff) Limited | Construction | 2012 |
| MANNAT28 Ltd | Wholesale & retail | 2023 |
| Manneh Global Ltd | Wholesale & retail | 2025 |
| Manning and Morris Estate Agents Limited | Real estate | 2025 |
| Manning Resource Solutions Ltd | Information & communication | 2020 |
| Mannings Property Consultants Ltd | Real estate | 2020 |
| Mano Global Ltd | Other services | 2025 |
| Manoelena Limited | Hospitality | 2021 |
| Manor Brick Centres Limited | Wholesale & retail | 1996 |
| Manor Construction Services Limited | Construction | 2022 |
| Manor Court Llanishen Limited | Households | 2007 |
| Manor Estates Ground Care Limited | Administrative & support | 2003 |
| Manor Groves Associates Limited | Extraterritorial | 2026 |
| Manor House Autos Ltd | Wholesale & retail | 2021 |
| Manor Lane Services Company Limited | Wholesale & retail | 1973 |
| Manor Parc Holdings Limited | Financial services | 2015 |
| Manor Park Residential Home Limited | Other services | 2005 |
| Manor Park Works Limited | Real estate | 2018 |
| Manor Property Services Ltd | Construction | 2015 |
| Manortown Trading Limited | Other services | 2023 |
| Manorway Academy | Education | 2016 |
| Manpower 24-7 Surveillance Ltd | Administrative & support | 2021 |
| Manpreet SINGH1 Ltd | Construction | 2025 |
| Mans Trading Limited | Wholesale & retail | 2021 |
| Mansel Davies & SON Group Limited | Extraterritorial | 2020 |
| Mansfieldmike Limited | Professional & scientific | 2023 |
| Mansinova Ltd | Construction | 2025 |
| Mansion Central Brokers Ltd | Financial services | 2015 |
| Mansion Production Limited | Arts & recreation | 2013 |
| Manson Design Ltd | Professional & scientific | 2020 |
| Mansons Consulting Ltd | Professional & scientific | 2013 |
| Manta Subsea Group Limited | Professional & scientific | 2007 |
| Mantellumcl Ltd | Health & social care | 2021 |
| Manthar Ltd | Wholesale & retail | 2025 |
| Mantix - Install Ltd | Water & waste | 2016 |
| Mantram PVT Limited | Wholesale & retail | 2023 |
| Manuem Limited | Mining & quarrying | 2023 |
| Manufacturing Research Ltd | Manufacturing | 2021 |
| Manufacturing Services Wales Limited | Professional & scientific | 2016 |
| Manumit Limited | Manufacturing | 2017 |
| Manverra Limited | Professional & scientific | 2025 |
| Manwar Group Ltd | Real estate | 2017 |
| Many Many Monkeys Ltd | Arts & recreation | 2015 |
| Manye Foreign Trade Ltd | Wholesale & retail | 2024 |
| Manyfest Online Limited | Administrative & support | 2026 |
| Manymbyan Ltd | Financial services | 2025 |
| Manzotti Ltd | Wholesale & retail | 2025 |
| Maojw Ltd | Wholesale & retail | 2025 |
| Maotuo Technology Co., Ltd | Wholesale & retail | 2025 |
| Maozhou Ltd | Wholesale & retail | 2024 |
| MAP Electrical Installations Limited | Construction | 2026 |
| MAP Security Consultants Limited | Information & communication | 2015 |
| Map-Iq Ltd | Education | 2021 |
| Maple & Black Law Limited | Extraterritorial | 2012 |
| Maple Global Ltd | Wholesale & retail | 2024 |
| Maple Leaf Dragon 2.0 Limited | Real estate | 2024 |
| Maple Shade Estates Limited | Real estate | 2017 |
| Maple Talent Solutions Ltd | Administrative & support | 2024 |
| Maple Yankee Sports Limited | Arts & recreation | 2013 |
| Mapleash Limited | Health & social care | 2023 |
| Maplehirst Limited | Health & social care | 2009 |
| Maplin Construction & Management Ltd | Construction | 2017 |
| Mapwales Ltd | Real estate | 2019 |
| MAQ Transport Ltd | Transport & logistics | 2019 |
| Maqa Enterprise Limited | Wholesale & retail | 2025 |
| Maqteck Ltd | Wholesale & retail | 2019 |
| Maqueline Builders Limited | Construction | 2009 |
| MAR Developments Ltd | Construction | 2019 |
| MAR Manteca SP Ltd | Information & communication | 2025 |
| Marabou Consulting (UK) Ltd | Information & communication | 2022 |
| Maral Sanat Pardis Co., Ltd | Administrative & support | 2017 |
| Maranatha Business Services Limited | Health & social care | 2015 |
| Marbets Ltd | Other services | 2026 |
| Marble Arch Pads Ltd | Hospitality | 2017 |
| Marble Lock Estates Ltd | Real estate | 2024 |
| Marble Management Limited | Wholesale & retail | 2019 |
| Marble Poetry Limited | Information & communication | 2018 |
| Marble Trade Ltd | Wholesale & retail | 2024 |
| Marc 1 Bristol Ltd | Wholesale & retail | 2011 |
| Marc Evans Ltd | Other services | 2012 |
| Marc Penny Consultancy Ltd | Professional & scientific | 2025 |
| Marc Roberts Ltd | Wholesale & retail | 2020 |
| Marc Tomlinson Ltd | Construction | 2015 |
| Marcado PC | | 2014 |
| Marcar Media Ltd | Other services | 2016 |
| Marcel Formwork and Engineering Ltd | Administrative & support | 2016 |
| Marcel Mart Ltd | Wholesale & retail | 2025 |
| Marcel Molinari Limited | Information & communication | 2020 |
| Marcelis Retail Ltd | Wholesale & retail | 2026 |
| Marcgoodfellow UK Commercial Holding Ltd | Agriculture & fishing | 2021 |
| March Brothers Ltd | Hospitality | 2025 |
| March Garage Services Ltd | Wholesale & retail | 2021 |
| March Light Ltd | Information & communication | 2025 |
| March Logistics Limited | Other services | 2017 |