| Maoni Properties Limited | Real estate | 2022 |
| Maoni Solutions Limited | Professional & scientific | 2021 |
| Mapel Court Management Limited | Households | 2012 |
| Mapitom UK Limited | Real estate | 2020 |
| Marblerockholidays Ltd | Hospitality | 2025 |
| Marcia Mediation Limited | Professional & scientific | 2014 |
| Marine Decommissioning Services Limited | Water & waste | 2021 |
| Marine Timber Services Limited | Extraterritorial | 1973 |
| Mario Miniaci Limited | Wholesale & retail | 1968 |
| Mark Heaven Consulting Limited | Administrative & support | 2015 |
| Mark Heyes Plumbing and Heating Ltd | Construction | 2017 |
| Mark Higgins Motorsport Limited | Arts & recreation | 2012 |
| Markcar Enterprises Ltd | Manufacturing | 2008 |
| Marlis Holdings Ltd | Financial services | 2022 |
| Maroc Trade Ltd | Wholesale & retail | 2025 |
| Mars Building Construction Ltd | Administrative & support | 2021 |
| Marsland Medical Ltd | Health & social care | 2023 |
| Martin Global Limited | Professional & scientific | 2011 |
| Martom Consulting Limited | Professional & scientific | 2004 |
| Mascott Homes Limited | Real estate | 2012 |
| Mase Facilities Limited | Construction | 2019 |
| Maskew Cordon Ltd | Administrative & support | 2009 |
| Masland Foods Ltd | Hospitality | 2019 |
| Masqued Limited | Information & communication | 2022 |
| Massey House Residents Association Limited | Households | 1986 |
| Mast Estates Ltd | Real estate | 2017 |
| Mastana Limited | Hospitality | 2022 |
| Master Fryers Ltd | Hospitality | 2025 |
| Masters of Craft Limited | Other services | 2016 |
| Mather and Thomas Limited | Real estate | 2017 |
| Matilda Holdings (N/W) Limited | Financial services | 2024 |
| Matt Poole Academy Ltd | Administrative & support | 2022 |
| Mattinson Bedrooms Limited | Manufacturing | 2003 |
| Maximum Effort Art Ltd | Arts & recreation | 2017 |
| Maxland Properties Ltd | Construction | 2017 |
| Maxwell Healthcare Limited | Health & social care | 2008 |
| Maxyolo Limited | Wholesale & retail | 2016 |
| Mayfield Lodge (Salford) Management Co. Limited | Households | 1977 |
| Mayfield Valley Brain and Spine Ltd | Health & social care | 2019 |
| Mayforth Mortgage & Protection Limited | Financial services | 2021 |
| Mazel Resolutions Limited | Wholesale & retail | 2025 |
| Mbblu Design Services Ltd | Professional & scientific | 2011 |
| Mbts Associates Limited | Real estate | 2014 |
| Mccann Physiotherapy Ltd | Public administration | 2024 |
| Mccann-Christensen Limited | Professional & scientific | 1995 |
| Mccormick Tools Limited | Wholesale & retail | 1999 |
| Mccrory Qualification Services Ltd | Professional & scientific | 2022 |
| Mcdonagh Podcast Limited | Information & communication | 2023 |
| Mcglashan Energy Consultants Ltd | Professional & scientific | 2025 |
| MCI Consulting Ltd | Administrative & support | 2023 |
| Mcnulty Bradley Ltd | Financial services | 2021 |
| Mcquillan Insurance Brokers Limited | Professional & scientific | 2018 |
| MCR Barbers Ltd | Other services | 2021 |
| MCR Kitchen Limited | Hospitality | 2024 |
| MCR Quant Systems Limited | Information & communication | 2026 |
| MCR Short Stay Ltd | Real estate | 2024 |
| MCR Vending Limited | Wholesale & retail | 2025 |
| Mdlk Ltd | Health & social care | 2025 |
| MDM Developments Limited | Construction | 2000 |
| ME and YOU Education CIC | Education | 2022 |
| MEC Installations Limited | Construction | 2022 |
| MED Techno Limited | Health & social care | 2024 |
| Medentis UK Ltd | Health & social care | 2015 |
| Medex (NW) Limited | Health & social care | 2010 |
| Medhob Limited | Construction | 1979 |
| Media Connect Marketing Ltd | Professional & scientific | 2025 |
| Medicare Hub Ltd | Health & social care | 2023 |
| Medicines Management Direct Ltd | Professional & scientific | 2020 |
| Medico Tutoring Ltd | Education | 2024 |
| Medicus Oculi Ltd | Information & communication | 2022 |
| Meditsa Limited | Health & social care | 2025 |
| Medlock Gardens Management Company Limited | Households | 2023 |
| Medogast Ltd | Real estate | 2021 |
| Medsu MSK Ltd | Health & social care | 2025 |
| Medtecflo Limited | Professional & scientific | 2023 |
| Mega Digital Solutions Limited | Information & communication | 2016 |
| Mega Technologies Limited | Information & communication | 2017 |
| Megalodon Ltd | Financial services | 2020 |
| Meijae Ltd | Health & social care | 2023 |
| Mel's Computer Care Limited | Information & communication | 2010 |
| Melio Labs Ltd | Information & communication | 2024 |
| Melissa Cook Limited | Administrative & support | 2005 |
| Melrose House Management Company Limited | Real estate | 2018 |
| Mems Internet Marketing Limited | Wholesale & retail | 2002 |
| Menorquina (GB & Ireland) Ltd | Hospitality | 2005 |
| Meraki Sports Limited | Education | 2022 |
| Merecourt Management (NW) Ltd | Real estate | 2019 |
| Messaging Warehouse (UK) Ltd | Information & communication | 2002 |
| Metamorphix Solutions Ltd | Administrative & support | 2025 |
| MFA Football Academy Limited | Education | 2020 |
| MG Hourglass PT Limited | Other services | 2015 |
| MG Northwest Ltd | Real estate | 2023 |
| Mg&D Motors Limited | Wholesale & retail | 2020 |
| MGE Aesthetics Ltd | Health & social care | 2025 |
| MGL Floor Coverings Limited | Construction | 2005 |
| MGS Enterprises Ltd | Construction | 2020 |
| MH Estimating Ltd | Professional & scientific | 2021 |
| MH3 Limited | Education | 2015 |
| MHC Properties (Wirral) Ltd | Real estate | 2021 |
| MHC Smile Ltd | Health & social care | 2021 |