| Market Chips Norwich Limited | Hospitality | 2016 |
| Market Fresh (Hampshire) Ltd | Wholesale & retail | 2012 |
| Market Harborough Energy Centre Limited | Energy | 2023 |
| Market Kitchens and Joinery Limited | Construction | 2011 |
| Market Nail Bar Limited | Wholesale & retail | 2022 |
| Marketing Mavens Limited | Professional & scientific | 2009 |
| Marketing Productions Ltd | Extraterritorial | 2022 |
| Marketplace Vault Limited | Wholesale & retail | 2021 |
| Markitt Limited | Agriculture & fishing | 2013 |
| Markoleth Products Limited | Households | 2020 |
| Markrox Deliveries Ltd | Transport & logistics | 2025 |
| Marksmen Industry Limited | Manufacturing | 2025 |
| Marlborough House (Norwich) RTM Company Limited | Households | 2022 |
| Marlingford Consulting Ltd | Health & social care | 2015 |
| Marlingford Trading Limited | Agriculture & fishing | 2025 |
| Marlpit Estates Limited | Hospitality | 2015 |
| Marmalade Tree Limited | Wholesale & retail | 2000 |
| Marmarekas Grill Ltd | Hospitality | 2021 |
| Marmion Homes Ltd | Real estate | 2019 |
| Maroc Film Services Ltd | Information & communication | 2026 |
| Marrable & Co Accounting Services Ltd | Professional & scientific | 2017 |
| Marrakech Birmingham Ltd | Hospitality | 2015 |
| Marriot Domes Ltd | Hospitality | 2022 |
| Marriott Build Limited | Extraterritorial | 2020 |
| Marriott Lettings Ltd | Real estate | 2023 |
| Marrison Agriculture Limited | Agriculture & fishing | 2005 |
| Marsali Tweed Limited | Wholesale & retail | 2021 |
| Marsden Builders 1979 Limited | Construction | 2015 |
| Marsden Builders Management Limited | Professional & scientific | 2017 |
| Marsh and Humphrey Ltd | Construction | 2024 |
| Marsh Harrier Southport Limited | Hospitality | 2025 |
| Marshall & Williams Facilities Limited | Construction | 2018 |
| Marshall and Williams Property Holdings Limited | Administrative & support | 2020 |
| Marshall Thompson Media Consulting Limited | Extraterritorial | 2012 |
| Marshalls Foods Limited | Manufacturing | 2004 |
| Marsham Arms Limited | Hospitality | 2025 |
| Marsham Equi Holdings Limited | Wholesale & retail | 2024 |
| Marsham Saddlery and Country Clothing Ltd | Wholesale & retail | 2018 |
| Marshview Consulting Limited | Professional & scientific | 2024 |
| Marsolutions Ltd | Professional & scientific | 2011 |
| Marste Limited | Real estate | 2019 |
| Marstech Projects Ltd | Construction | 2012 |
| Marston York Coaching Ltd | Health & social care | 2017 |
| Mart Smart Ltd | Administrative & support | 2011 |
| Martali Management Limited | Construction | 2001 |
| Martello Hotel Limited | Construction | 2021 |
| Martha & Daughter Limited | Wholesale & retail | 2005 |
| Martha's Sugar Rhythms Ltd | Hospitality | 2025 |
| Martial Arts Alliance Ltd | Arts & recreation | 2006 |
| Martin & Acock Limited | Professional & scientific | 2005 |
| Martin & Daley Limited | Real estate | 2021 |
| Martin Barrett Limited | Administrative & support | 2010 |
| Martin Christopher Opticians Limited | Health & social care | 2002 |
| Martin CNC Limited | Manufacturing | 2007 |
| Martin Crannis Limited | Real estate | 1982 |
| Martin Dobson Associates Ltd | Professional & scientific | 2011 |
| Martin Francis Limited | Real estate | 2007 |
| Martin Fuel Service Ltd | Wholesale & retail | 2018 |
| Martin Hailes Design Ltd | Other services | 2013 |
| Martin Holdings Limited | Financial services | 2026 |
| Martin Howe Architectural Services Ltd | Professional & scientific | 2019 |
| Martin IT Services Ltd | Information & communication | 2015 |
| Martin K Properties Ltd | Real estate | 2026 |
| Martin Law Commercial Vehicle Sales Ltd | Wholesale & retail | 2021 |
| Martin Renewables Limited | Energy | 2012 |
| Martin Reynolds Ltd | Information & communication | 2015 |
| Martin Rooth (City) Ltd | Administrative & support | 1998 |
| Martin Smith Independent Financial Adviser Ltd | Financial services | 2018 |
| Martin Thompson Services Limited | Mining & quarrying | 2017 |
| Martin Tisshaw Accounts Limited | Professional & scientific | 2020 |
| Martin Wones Electrical Limited | Construction | 2023 |
| Martin's Carpets Limited | Wholesale & retail | 2003 |
| Martinkhs Ltd | Other services | 2025 |
| Martins Maintenance Solutions Ltd | Administrative & support | 2015 |
| Martlet Farms NO 1 Limited | Administrative & support | 2023 |
| Martlet Farms NO 2 Limited | Administrative & support | 2023 |
| Marty Rich Ltd | Information & communication | 2012 |
| Martyn J Green Limited | Administrative & support | 2015 |
| Martyn Richards Research Limited | Professional & scientific | 2006 |
| Marvellous Medical Services Ltd | Health & social care | 2016 |
| Maryam Mohammad Ltd | Wholesale & retail | 2025 |
| MAS Driver Limited | Transport & logistics | 2015 |
| MAS HOMEWARE25 Limited | Wholesale & retail | 2020 |
| MAS Mortgages Ltd | Financial services | 2022 |
| Masala FIX Ltd | Hospitality | 2025 |
| Masalamint Ltd | Hospitality | 2026 |
| Mash Limited | Wholesale & retail | 2008 |
| Mash-Lo Cleaning Ltd | Construction | 2025 |
| Maskell Electrical Contractors Ltd | Construction | 2018 |
| Mason Decorators Limited | Construction | 2011 |
| Mason Fitness Group Ltd | Arts & recreation | 2018 |
| Mason Road Management Company Limited | Real estate | 2011 |
| Mason Williams Limited | Professional & scientific | 2013 |
| Mass-Chem Ltd | Wholesale & retail | 2020 |
| Massalla Lounge Worcester Limited | Hospitality | 2017 |
| Masseria Foodstores Limited | Hospitality | 2001 |
| Massinghams Ltd | Administrative & support | 2019 |
| Massive Dynamic International Holdings Ltd | Manufacturing | 2012 |
| Massive Dynamic Technology Ltd | Information & communication | 2017 |
| Massive Small Manufacturing Ltd | Professional & scientific | 2019 |