| M J DESIGN2000 Ltd | Manufacturing | 2019 |
| Maine Microwave Services Limited | Manufacturing | 2017 |
| Maison Delicious Ltd | Wholesale & retail | 2025 |
| Malone Fabrics Group Limited | Wholesale & retail | 2024 |
| Malone Property Group Ltd | Real estate | 2025 |
| Marben Properties Limited | Real estate | 2017 |
| Maria Developments Ltd | Real estate | 2019 |
| Marshall Homes N.I. Limited | Construction | 2015 |
| Mastiff [IA] Ltd | Extraterritorial | 2024 |
| Mathsbuddy Limited | Education | 2009 |
| Mcmurray Tractors Ltd | Manufacturing | 2017 |
| Mcveigh Transport Ltd | Water & waste | 2021 |
| MGK KG LLP | | 2025 |
| MGK Kingsgate Ltd | Construction | 2024 |
| Mill Mews Hillsborough Ltd | Households | 2024 |
| Mill-Pond View Consultancy Limited | Construction | 2020 |
| Mill-Pond View Developments Ltd | Construction | 2019 |
| Millpond Projects Limited | Construction | 2025 |
| MJA Property Development Limited | Real estate | 2011 |
| Mmcl Consultancy Ltd | Real estate | 2025 |
| Morrow Commercial Holdings Ltd | Financial services | 2022 |
| Morrow Retail Holdings Limited | Professional & scientific | 2014 |
| Mortgage First (Holdings) Limited | Financial services | 2021 |
| Mortgage First Newry Limited | Financial services | 2021 |
| Mortgage First NI Ltd | Financial services | 2016 |
| Moss Lane Developments Limited | Construction | 2005 |
| Moss Lane Holdings Limited | Financial services | 2005 |
| Motorhomehireni Limited | Administrative & support | 2015 |
| Mount Property Development Limited | Real estate | 2000 |
| Mountview Generator Services Limited | Manufacturing | 2013 |
| MOY Estates Limited | Real estate | 2003 |
| MS Plant Services Ltd | Manufacturing | 2025 |
| MTK Properties Ltd | Construction | 2012 |
| Mulholland Courier Services Limited | Transport & logistics | 2014 |
| MW Assessors NI Ltd | Professional & scientific | 2019 |
| N Gordon Properties Limited | Real estate | 2025 |
| Naughton M6 Ltd | Wholesale & retail | 2023 |
| Neal Lucas Recruitment Limited | Administrative & support | 2009 |
| Neptune Dunlop Limited | Construction | 2025 |
| Neptune Group Limited | Financial services | 2020 |
| Neptune Land Promotion Limited | Construction | 2015 |
| Neptune Moygashel Limited | Real estate | 2015 |
| New R China Ltd | Hospitality | 2020 |
| NI Timberframes Ltd | Manufacturing | 2023 |
| NI Vintage Ltd | Wholesale & retail | 2025 |
| Nifx Ltd | Financial services | 2014 |
| Nirvana Tyres Limited | Wholesale & retail | 2012 |
| NN Consultancy Limited | Professional & scientific | 2026 |
| NO More Traffik | Other services | 2012 |
| North Armagh Motor Club | Arts & recreation | 2009 |
| Northern Excavators Limited | Wholesale & retail | 1969 |
| Northern Ireland Agricultural Research and Development Council - the | Agriculture & fishing | 1999 |
| Northwin (Balmoral and Wellington) Limited | Administrative & support | 2000 |
| Northwin (Belfast) Limited | Administrative & support | 2000 |
| Northwin (Intermediate) (Belfast) Limited | Financial services | 1998 |
| Nugent Brothers Enterprises Ltd | Construction | 2024 |
| Oatlands Farm Ltd | Agriculture & fishing | 2022 |
| Oatlands Leisure Ltd | Arts & recreation | 2020 |
| Oatlands Pool Limited | Arts & recreation | 2018 |
| Offlineflix Limited | Information & communication | 2024 |
| Oiltrack Limited | Information & communication | 2017 |
| Onex Ltd | Manufacturing | 2004 |
| Onsocial Marketing Ltd | Information & communication | 2023 |
| Opnetblue Ltd | Information & communication | 2024 |
| Orchard Grove Properties Limited | Real estate | 2015 |
| Orthodent Surgical Limited | Health & social care | 2023 |
| Orthoderm Ltd | Health & social care | 2007 |
| Ourniteout Ltd | Manufacturing | 2012 |
| Outfit Fitness Ltd | Arts & recreation | 2020 |
| OWL and Pussycat Cafe Ltd | Hospitality | 2016 |
| Pain to Performance Physio Ltd | Health & social care | 2024 |
| Panther PCM Ltd | Professional & scientific | 2017 |
| Parkview Farmhouse Limited | Hospitality | 2024 |
| Patterson Strategy Group Ltd | Professional & scientific | 2025 |
| Paul Armstrong Surfacing Limited | Construction | 2009 |
| Paul Hampton Cafe Ltd | Hospitality | 2019 |
| Peak Developements Limited | Construction | 2025 |
| Peckham Marine Ltd | Professional & scientific | 2024 |
| Peter Thomas Photography Ltd | Professional & scientific | 2015 |
| Petry Consultants Ltd | Professional & scientific | 2023 |
| Phoenix Investments & Property Services Ltd | Financial services | 2025 |
| Pickle and Smoke @ Hearth Limited | Hospitality | 2025 |
| Pilastro Investments Limited | Hospitality | 2025 |
| Pizza Table Events Ltd | Hospitality | 2023 |
| Pizza Table NI Ltd | Wholesale & retail | 2021 |
| Plastec (Northern Ireland) Ltd | Wholesale & retail | 2011 |
| Plates Hillsborough Limited | Hospitality | 2026 |
| Plimsoll Analysis Limited | Information & communication | 1998 |
| PLT Sourcing Ltd | Wholesale & retail | 2013 |
| PM IT Contracting Ltd | Information & communication | 2023 |
| Pmfm Consulting Ltd | Professional & scientific | 2017 |
| Pneuvo Biotechnology Ltd | Professional & scientific | 2021 |
| Popcon Properties Ltd | Real estate | 2024 |
| Portfolio Nominees Limited | Professional & scientific | 1986 |
| Positive Steps Outdoors C.I.C. | Health & social care | 2022 |
| Precision Plastic Surgery Ltd | Health & social care | 2022 |
| Protect Holdings Ltd | Financial services | 2021 |
| Provincial (NI) Limited | Wholesale & retail | 2013 |
| Qualmet Engineering & Design (QED) Ltd | Manufacturing | 2013 |
| Quantum Systemes Ltd | Manufacturing | 2022 |