| Mhriw Limited | Professional & scientific | 2025 |
| Michael Bradley (Holdings) Limited | Professional & scientific | 1999 |
| Michael Bradley (Property) Limited | Real estate | 1999 |
| Michael Dickinson Limited | Professional & scientific | 2014 |
| Michael Preston ICT Consultants Ltd | Other services | 2008 |
| Micralite (IP) Limited | Wholesale & retail | 2017 |
| Micralite Holdings Limited | Wholesale & retail | 2017 |
| Micralite Limited | Wholesale & retail | 2001 |
| Microera Power International Ltd | Manufacturing | 2019 |
| MIH12 Limited | Arts & recreation | 2020 |
| Millans Investments Limited | Real estate | 1964 |
| Miller Education LLP | | 2024 |
| Millidon Designs Limited | Information & communication | 2013 |
| Milton Park (Gargrave) Ltd | Hospitality | 2012 |
| Mindalot Limited | Health & social care | 2013 |
| Minds Temple Ltd | Wholesale & retail | 2025 |
| Mitchell Development Services Limited | Construction | 2009 |
| Mitchell Farrar Group LLP | | 2009 |
| Mitchell Farrar Holdings Limited | Financial services | 2011 |
| Mitchell Wellock Limited | Professional & scientific | 2017 |
| Mitchells Group Limited | Professional & scientific | 2005 |
| MJG Consultancy Ltd | Construction | 2016 |
| MJH Medical Enterprise Limited | Education | 2019 |
| MJL Groundwork Services Ltd | Construction | 2024 |
| MJP Catering Limited | Hospitality | 2014 |
| MK2 Energy Limited | Administrative & support | 2022 |
| MLB Properties NW Limited | Real estate | 2017 |
| MLX Training & Compliance Limited | Administrative & support | 2010 |
| Mobili Office Design International LLP | | 2010 |
| Mobili Office Limited | Manufacturing | 1996 |
| Modern by Products UK Ltd | Professional & scientific | 2020 |
| Modish ME Limited | Wholesale & retail | 2016 |
| Modyfi Limited | Information & communication | 2021 |
| Monica Tinoy Amparo Healthcare Ltd | Health & social care | 2025 |
| Monolith Digital Limited | Information & communication | 2020 |
| Monsterweb Ltd | Information & communication | 2012 |
| Moorber Holdings Limited | Real estate | 2022 |
| Moorcroft Holiday Lets & Rentals Ltd | Hospitality | 2024 |
| Moorland Design and Consultancy Limited | Professional & scientific | 2020 |
| Moorland Private Junior School Ltd | Education | 2023 |
| Moorland Private Nursery Ltd | Health & social care | 2023 |
| Moorprint (Ilkley) Limited | Manufacturing | 2006 |
| Moorview Community Social Club Ltd | Hospitality | 2020 |
| Mora Health Ltd | Wholesale & retail | 2026 |
| Moraine Capital Limited | Professional & scientific | 2016 |
| Motiontm Ltd | Information & communication | 2018 |
| Motor GAP Limited | Administrative & support | 2009 |
| Motor Marketing Solutions Limited | Other services | 2021 |
| Motorhome Spare Parts Ltd | Wholesale & retail | 2026 |
| Moule Media Limited | Professional & scientific | 2006 |
| Movie Cameras Inc Ltd | Information & communication | 2013 |
| Moving Masters Limited | Information & communication | 2005 |
| Mowcare Lawnmower Services Ltd | Other services | 2020 |
| MPR Lettings Limited | Administrative & support | 2017 |
| Mpserellis Limited | Information & communication | 2008 |
| MR Whippy Derby Limited | Wholesale & retail | 2022 |
| MR Whippy East Midlands Limited | Wholesale & retail | 2022 |
| MR. Scratchings Limited | Wholesale & retail | 2002 |
| MRT Development and Builders Ltd | Construction | 2020 |
| MS Peaches Ltd | Wholesale & retail | 2021 |
| MS011 Limited | Hospitality | 2016 |
| MSC Education Consultancy Ltd | Education | 2024 |
| Mshughes Ltd | Construction | 2024 |
| Muckle Ventures Limited | Hospitality | 2025 |
| Muddie Boots Limited | Hospitality | 2021 |
| MW & RF Brewster and Sons Limited | Construction | 2005 |
| My Event Genie Limited | Construction | 2006 |
| My Expedition Rocks Ltd | Education | 2018 |
| Myers Consultants Limited | Professional & scientific | 2026 |
| Myndtime Ltd | Manufacturing | 2025 |
| Myrtle Estates Limited | Real estate | 1936 |
| N Smith Driveways and Patios Limited | Construction | 2023 |
| N Smith Paving and Landscaping Contractors Limited | Administrative & support | 2022 |
| N Smith Roofing Ltd | Construction | 2025 |
| N. Peal (Retail) Limited | Wholesale & retail | 2006 |
| Nada Restante Aqui Limited | Extraterritorial | 2021 |
| Namaste - UK Limited | Wholesale & retail | 2002 |
| Namebadge Limited | Extraterritorial | 1944 |
| NAS Property Consulting Ltd | Real estate | 2025 |
| National Coppice Federation | Agriculture & fishing | 2013 |
| Natural Systems Limited | Construction | 2007 |
| Nature Restoration Limited | Agriculture & fishing | 2023 |
| Navigate: the Inner Compass Ltd | Professional & scientific | 2025 |
| Naylor Homes Ltd | Real estate | 2018 |
| Naylor Made Rentals Limited | Real estate | 2024 |
| Naylor Made Smiles Ltd | Health & social care | 2022 |
| NBP Plumbing & Heating Limited | Construction | 2024 |
| NER 1903 Electric Autocar Trust | Transport & logistics | 2004 |
| Nest Property Network Ltd | Real estate | 2024 |
| Nestegg Financial Services Limited | Financial services | 2021 |
| NET Zero (Contracts) Ltd | Agriculture & fishing | 2023 |
| NET Zero (North) Limited | Agriculture & fishing | 2022 |
| NET Zero (Rewilding) Ltd | Agriculture & fishing | 2023 |
| NET Zero (Solar) Ltd | Construction | 2023 |
| NET Zero (Wind) Ltd | Professional & scientific | 2023 |
| Nethergill LLP | | 2020 |
| Network Scientific Holdings Ltd | Financial services | 2021 |
| Network Scientific Ltd | Administrative & support | 2010 |
| Network Scientific Sales Ltd | Administrative & support | 2021 |
| New Image Automotive Limited | Wholesale & retail | 2016 |