| Manna Baruch Hospitality Limited | Hospitality | 2019 |
| Mannings USA (UK) Limited | Professional & scientific | 2007 |
| Manny Ross Limited | Administrative & support | 2019 |
| Manor Lodge Southport Limited | Wholesale & retail | 2010 |
| Manta RAY Communications Ltd | Professional & scientific | 2023 |
| Manuel Builders Ltd | Construction | 2012 |
| Manx Direct Ltd. | Wholesale & retail | 2009 |
| Many Happy Returns Limited | Administrative & support | 2019 |
| March Baines Limited | Information & communication | 2017 |
| Marcomms (UK) Limited | Information & communication | 2013 |
| Marcus Memorials Limited | Manufacturing | 2025 |
| Marcus Ross Mosey Limited | Professional & scientific | 2024 |
| Margaret Hobson & Associates Limited | Education | 2010 |
| Mari's Childcare Ltd | Education | 2016 |
| Mariano Auto Repairs Limited | Manufacturing | 2013 |
| Marina Court (Rufford) Management Company Limited | Households | 2006 |
| Marina Properties (Southport) Limited | Real estate | 2004 |
| Marine Drive Southport Limited | Real estate | 2014 |
| Marine Safety Consultancy Ltd | Professional & scientific | 2013 |
| Maritime Court Limited | Households | 2005 |
| Marius Dragu Logistics Limited | Transport & logistics | 2021 |
| Mark Knowles Limited | Construction | 2011 |
| Mark T Crighton Ltd. | Financial services | 2006 |
| Mark Webster Engineering Ltd | Manufacturing | 2024 |
| Market Harborough 58 Ltd | Hospitality | 2018 |
| Market Street (Southport) Limited | Real estate | 2007 |
| Marlborough Management Southport Limited | Real estate | 2013 |
| Marlo Consulting Ltd | Administrative & support | 2021 |
| Marloo Sailing Ltd | Education | 2026 |
| Marmaris Barber Southport Ltd | Other services | 2025 |
| Marmaris Southport Ltd | Hospitality | 2019 |
| Marsh Tech Limited | Professional & scientific | 2009 |
| Marshall Brickwork Design & Building Services Ltd | Construction | 2018 |
| Marshall Estates Ltd | Real estate | 2021 |
| Marshall Lettings Ltd | Real estate | 2019 |
| Marshside Fishing Co. Limited | Agriculture & fishing | 2002 |
| Marshside Health Club Ltd | Administrative & support | 2007 |
| Marshside Property Limited | Real estate | 2014 |
| Martin Fleet Rental Ltd | Administrative & support | 2016 |
| Martin Motors (Southport) Limited | Real estate | 1980 |
| Martin Taxi Rentals Ltd | Administrative & support | 2016 |
| Martland Mortgages.Com Limited | Financial services | 2008 |
| Martland Rollers Ltd. | Administrative & support | 2016 |
| Marvalous Competitions Ltd | Arts & recreation | 2025 |
| Marvel Business Group Ltd | Professional & scientific | 2020 |
| Marymar Transport Ltd | Transport & logistics | 2017 |
| Masef Holdings Limited | Manufacturing | 2017 |
| Masonic Nominees (Southport) Limited | Hospitality | 1949 |
| Massam & Graham Ltd | Financial services | 2025 |
| Massey Motor Group Ltd | Wholesale & retail | 2025 |
| Master Lock & Safe (Holdings) Limited | Financial services | 2023 |
| Master Valet Limited | Administrative & support | 2009 |
| Mastercraft Kitchens Ltd | Construction | 2020 |
| Mastercraft Manufacturing Ltd | Manufacturing | 2019 |
| Masters Group Building Services Ltd | Construction | 2024 |
| Masters VBR Ltd | Wholesale & retail | 2019 |
| MAT Szwarz Ltd | Transport & logistics | 2025 |
| Match 72 Limited | Administrative & support | 2016 |
| Matchdream Limited | Construction | 2020 |
| Mathew Butterworth Associates Ltd | Professional & scientific | 2008 |
| Matloz Limited | Real estate | 2009 |
| Matrix Sales Ltd | Other services | 2019 |
| Matrix Total Solutions Ltd | Professional & scientific | 2016 |
| Matt@ Limited | Manufacturing | 2022 |
| Matthew Baldwin Golf Limited | Professional & scientific | 2014 |
| Matthew Baron & Sons Limited | Wholesale & retail | 1927 |
| Maureen's Fabrics Ltd | Wholesale & retail | 2025 |
| MAX Healthcare Group Ltd | Health & social care | 2022 |
| Maxicus Investments Ltd | Extraterritorial | 2024 |
| Maxweald Finance Limited | Extraterritorial | 1989 |
| MAY Networks Ltd | Administrative & support | 2025 |
| Maya Headwear Ltd | Manufacturing | 2022 |
| Maya Therapies Ltd | Health & social care | 2025 |
| Mayda Technologies Ltd | Information & communication | 2023 |
| Mayfair Court (Southport) Limited | Households | 1973 |
| Mayhem Motorcycle Training Ltd | Education | 2008 |
| Mayison Limited | Construction | 2026 |
| Mays Elite Finance Limited | Wholesale & retail | 2019 |
| Maysam Groups Ltd | Manufacturing | 2019 |
| Mazd Trading Ltd | Wholesale & retail | 2020 |
| MB Assets Ltd | Professional & scientific | 2010 |
| Mbkp Properties Ltd | Real estate | 2020 |
| MBW & Partners Limited | Arts & recreation | 2018 |
| Mcallister Securenet Ltd | Information & communication | 2024 |
| Mcbride Enterprises Ltd | Professional & scientific | 2024 |
| Mccains Car Service & MOT Ltd | Wholesale & retail | 2005 |
| Mccarthy Property Developments Ltd | Real estate | 2025 |
| Mccord Logistics Ltd | Professional & scientific | 2020 |
| Mccrimmon Property Management Limited | Households | 2018 |
| Mcgorry Construction Limited | Construction | 2016 |
| Mcgorry Developments Limited | Construction | 2010 |
| MCL Medics Limited | Professional & scientific | 2007 |
| Mcnamara Consult Ltd | Other services | 2017 |
| Mcrennie Consulting Ltd | Information & communication | 2024 |
| MCV Capital Holdings Ltd | Financial services | 2023 |
| MCV Capital Limited | Real estate | 2015 |
| MCV Property Company Ltd | Real estate | 2021 |
| MD Builders (Southport) Ltd | Construction | 2025 |
| MD Network Solutions Ltd | Construction | 2009 |
| MDA Logistics Ltd | Transport & logistics | 2023 |