| Medicare Chemists Limited | Wholesale & retail | 1991 |
| Meera Consultancy Services (UK) Limited | Professional & scientific | 2007 |
| Melia Smith & Jones Limited | Professional & scientific | 2000 |
| Melvyn Thorpe Langford Road (Flats Management) Limited | Households | 1979 |
| Memusi Foundation | Professional & scientific | 2009 |
| Men's Health Plus Limited | Health & social care | 2006 |
| Merlin Precision Engineering Limited | Manufacturing | 2000 |
| Metropolis NLP Ltd | Other services | 2007 |
| Mewcan Limited | Manufacturing | 2007 |
| Miabri Limited | Information & communication | 2007 |
| Michael Eyres Partnership LLP | | 2007 |
| Michael J. Lumb Fuels Limited | Wholesale & retail | 2003 |
| Miclyn Limited | Real estate | 2006 |
| Middleton Elderly AID | Health & social care | 2003 |
| Milelands Limited | Health & social care | 1985 |
| Millbridge Limited | | 1990 |
| Millennium Entertainment Ltd | Hospitality | 1997 |
| Mineral Craft North Limited | Wholesale & retail | 1993 |
| Mint Properties (Yorkshire) Limited | Real estate | 2004 |
| Mirfield Motor Spares Ltd. | Wholesale & retail | 2001 |
| Mirfield Properties Limited | Real estate | 1999 |
| Mirzai Limited | Construction | 1998 |
| Misra & Misra LLP | | 2004 |
| Mitha (Trafalgar) & Co | Wholesale & retail | 2003 |
| Mitre Estates Limited | Construction | 1972 |
| Mitre Residential LLP | | 2005 |
| MJD Enterprises Limited | Professional & scientific | 2007 |
| Mmcg Topco Holdings Ltd | Professional & scientific | 2022 |
| MMG Business Process Solutions Limited | Professional & scientific | 2006 |
| Modality Systems Limited | Information & communication | 2007 |
| Mone Brothers (Properties) Limited | Construction | 1979 |
| Moorhouse Opticians (Northern) Limited | Health & social care | 1974 |
| Moortown Estate Agency Limited | Professional & scientific | 1968 |
| Moortown Plumbing and Heating Services Limited | Construction | 2003 |
| Moorview Systems Limited | Information & communication | 2006 |
| More Than Mobility Ltd | Professional & scientific | 2007 |
| Morgan Hughes Limited | Construction | 2000 |
| Morgan-Verne Executive Travel Limited | Extraterritorial | 2007 |
| Morgan-Verne Limited | Extraterritorial | 2008 |
| Morphet Service Limited | Professional & scientific | 2003 |
| Morton Logistics Limited | Extraterritorial | 2007 |
| Morton Meadow Logistics Limited | Administrative & support | 2000 |
| Mostyn Limited | Professional & scientific | 2000 |
| Motech Services (Yorkshire) Limited | Construction | 2004 |
| Motorseal Gaskets Limited | Manufacturing | 1983 |
| Mott Trade Co., Ltd | Wholesale & retail | 2025 |
| Mount Automotive Solutions Limited | Wholesale & retail | 2005 |
| Mount Dental Surgery Limited | Health & social care | 2007 |
| Mount Garage Limited | Real estate | 1950 |
| Movie Gazette Limited | Information & communication | 2005 |
| MPS Building Contractors Limited | Wholesale & retail | 2005 |
| MS Online Solutions Ltd | Wholesale & retail | 2024 |
| Msig Ltd | Construction | 2016 |
| MTW Architectural Limited | Manufacturing | 2005 |
| Mughal Jewellers Ltd | Wholesale & retail | 2003 |
| Multischeme Limited | Construction | 1997 |
| Musical Collectables Limited | Arts & recreation | 1996 |
| MW Electrics Limited | Construction | 2007 |
| My Plant Ltd | Administrative & support | 2009 |
| Myers Skip Hire Ltd | Water & waste | 1977 |
| Myers Software Services Limited | Information & communication | 2007 |
| Mytum & Selby Waste Holdings Limited | Financial services | 2024 |
| N K Wood Limited | Professional & scientific | 2007 |
| N S Project Management Limited | Information & communication | 2008 |
| N. D. Building Limited | Construction | 2004 |
| N. E. Holden Limited | Construction | 2003 |
| N.D. ENG Ltd | Manufacturing | 2007 |
| Nadcom Europe Consulting Limited | Information & communication | 2003 |
| Nangla Court Ltd | Real estate | 2005 |
| Narang Wholesalers Limited | Wholesale & retail | 1995 |
| Nasstar (UK) Limited | Information & communication | 1998 |
| Nasstar for Recruitment Limited | Information & communication | 2002 |
| Nasstar Limited | Administrative & support | 2018 |
| Nasstar Managed Services Group Limited | Information & communication | 2005 |
| Nasstar Services Limited | Information & communication | 2005 |
| Nasstar South Limited | Information & communication | 2004 |
| Nasstar Trading Limited | Information & communication | 1999 |
| National Business College Limited | Education | 2002 |
| Nayler Chemicals Limited | Manufacturing | 1981 |
| NB Plumbing & Heating Limited | Construction | 2006 |
| NEC (Electrical) Limited | Construction | 2003 |
| Nectar Trading Limited | Other services | 2024 |
| Neelam Limited | Information & communication | 2001 |
| Neil Paxman Limited | Other services | 2006 |
| Neil Walters Property Services Limited | Administrative & support | 2004 |
| Nelson Street (Queensbury) Management Limited | Professional & scientific | 2007 |
| Neoligaments Limited | Professional & scientific | 2000 |
| Neptune Diner Limited | Hospitality | 2005 |
| New ERA Carpet Co Limited | Wholesale & retail | 1959 |
| New Guard Coatings Limited | Manufacturing | 1977 |
| New Heights SLT Ltd | Health & social care | 2023 |
| New Holland Dock Wharfingers Limited | Transport & logistics | 1986 |
| New Leaf IT Consultancy Ltd | Other services | 2016 |
| Newburn Power Limited | Administrative & support | 2007 |
| Newly Weds Foods Acquisition Limited | Administrative & support | 2002 |
| Newly Weds Foods European Trading | | 1991 |
| Newly Weds Foods Limited | Manufacturing | 1942 |
| Newmarket Garage (Otley) Limited | | 1982 |
| Newspoint (Arndale) Ltd | Wholesale & retail | 2007 |
| Newspoint (Kirkgate) Ltd | Wholesale & retail | 2007 |