| MB Gym Co Ltd | Education | 2026 |
| MB Property Dreams Ltd | Real estate | 2024 |
| MB Seeley Floor Screeding Limited | Construction | 2024 |
| MBC Artist Ltd | Arts & recreation | 2024 |
| Mben Holdings Ltd | Financial services | 2019 |
| Mbgs Transport Ltd | Wholesale & retail | 2017 |
| MBW Retail Limited | Transport & logistics | 2026 |
| MC Crory Access Solutions Ltd | Construction | 2013 |
| MC Daid Optical Ltd | Health & social care | 2015 |
| MC Film Productions Limited | Information & communication | 2019 |
| Mcaleese Marine Ltd | Manufacturing | 2025 |
| Mcalinden & Murtagh Limited | Other services | 2006 |
| Mcalinden Electrical Contractors Limited | Construction | 2018 |
| Mcalinden Holdings Ltd | Wholesale & retail | 2025 |
| Mcareavey Joinery Limited | Manufacturing | 1989 |
| Mcareavey Properties Limited | Real estate | 2004 |
| Mcavoy Windows Ltd | Wholesale & retail | 2024 |
| MCC Property Construction Limited | Construction | 2014 |
| MCC Scaffolding Limited | Administrative & support | 2010 |
| Mccabrey Cycles Ltd | Wholesale & retail | 2024 |
| Mccann Venture Limited | Real estate | 2026 |
| Mccarthy Properties (Lurgan) Ltd | Real estate | 2025 |
| Mccavigan Construction Limited | Construction | 2023 |
| Mccleary & Company Ltd | Professional & scientific | 2003 |
| Mccleary Trustees Ltd | Professional & scientific | 2017 |
| Mcclelland Auto Service Limited | Wholesale & retail | 2023 |
| Mcclure Property Ltd | Real estate | 2024 |
| Mcconville Developments Limited | Construction | 2019 |
| Mcconville Memorials Ltd | Manufacturing | 2016 |
| Mccourt Mcglone Solicitors Limited | Professional & scientific | 2022 |
| Mccrory Access (Holdings) Limited | Financial services | 2022 |
| Mccrum & Sons Limited | Wholesale & retail | 2024 |
| Mccrums Motorcycles Ltd | Wholesale & retail | 2018 |
| MCD Building Projects Ltd | Construction | 2020 |
| Mcdonald Scaffolding Limited | Construction | 2025 |
| Mcdowell Enterprises Ltd | Real estate | 2026 |
| MCE Kitchens Limited | Construction | 2026 |
| Mcevoy Properties Ltd | Real estate | 2017 |
| Mcgaffin Properties Limited | Real estate | 2021 |
| Mcgibbon Consultancy & Safeguarding Services Limited | Health & social care | 2019 |
| Mcgilly Construction Ltd | Construction | 2023 |
| Mcginn Investments Ltd. | Extraterritorial | 2013 |
| Mcgowans CBD Store Ltd | Wholesale & retail | 2018 |
| Mcgurgan Holdings Ltd | Extraterritorial | 2016 |
| Mckeever Contracts Ltd | Transport & logistics | 2017 |
| Mckeown Group Limited | Hospitality | 2024 |
| Mckeown Manufacturing Ltd | Manufacturing | 2026 |
| Mckeown Renovations Ltd | Real estate | 2025 |
| Mcknights Hill Management Company Limited | Households | 2016 |
| Mcmahon Hearty Mckee Solicitors Ltd | Professional & scientific | 2011 |
| Mcmullan Holdings Limited | Financial services | 2024 |
| Mcmurray Fuels Ltd | Wholesale & retail | 2006 |
| Mcnally Guitars Ltd | Manufacturing | 2019 |
| Mcquades DIY & Hardware Ltd | Wholesale & retail | 2026 |
| Mcshane & Bros Limited | Hospitality | 2018 |
| MDB Tech + Transition Ltd | Information & communication | 2023 |
| MDE Engineering Limited | Manufacturing | 2014 |
| MDK Construction Ltd | Construction | 2006 |
| MDK Homes Ltd | Construction | 2017 |
| Meadows Auction Company Ltd | Wholesale & retail | 2024 |
| Meadowview Court Richhill MGT Ltd | Households | 2015 |
| Meat Merchant Limited - the | Extraterritorial | 2009 |
| Mebdent Ltd | Health & social care | 2014 |
| Medical Print Limited | Professional & scientific | 2010 |
| Medimec Limited | Wholesale & retail | 2025 |
| Medium Speed Engine Repair Limited | Manufacturing | 2022 |
| Meelmore Textiles Limited | Wholesale & retail | 2024 |
| Mega Mane Limited | Wholesale & retail | 2015 |
| Mega Mane Products Limited | Health & social care | 2022 |
| Melaps Ltd | Professional & scientific | 2010 |
| Melikids Ltd | Wholesale & retail | 2023 |
| Merchant (Lake Road) Ltd | Construction | 2019 |
| Merchant Estates Ltd | Real estate | 2008 |
| Merchant Quay Enterprises Limited | Professional & scientific | 2023 |
| Mercia Square Limited | Real estate | 2006 |
| Meridian Car Park Ltd | Real estate | 2026 |
| Meridian Court Ltd | Real estate | 2021 |
| Meridian PC Ltd | Real estate | 2026 |
| Merrywood Business Furniture Ltd | Manufacturing | 2002 |
| Metallart Limited | Extraterritorial | 2005 |
| Mexican Imports Ltd | Wholesale & retail | 2022 |
| MFJ Contracts Limited | Wholesale & retail | 2018 |
| MGC Building Contractors Limited | Construction | 2019 |
| MGM Associates Limited | Financial services | 2011 |
| MH 2020 Limited | Financial services | 2020 |
| MHM Developments Ltd | Construction | 2021 |
| MHP Clinic Ltd | Health & social care | 2020 |
| Michael Hannath Limited | Real estate | 2006 |
| Michael Owens Property Ltd | Real estate | 2026 |
| Micoh Nxtjee Brothers Ltd | Health & social care | 2024 |
| MID Ulster Aviation Ltd | Administrative & support | 2021 |
| Midnight Haunt Moira Ltd | Hospitality | 2026 |
| Migrant Centre NI Ltd | Health & social care | 2012 |
| Miki@Vesi Limited | Administrative & support | 2026 |
| Milestone Financial Ltd | Financial services | 2014 |
| Mill Logistics Ltd | Manufacturing | 2017 |
| Mill Meadows Management Company (N.I.) Ltd | Households | 2015 |
| Mill Street Estates Ltd | Real estate | 2014 |
| Millars Shoe Store Ltd | Wholesale & retail | 2002 |
| Millenium Way Developments Limited | Construction | 2019 |