| Lionheart Public Affairs Ltd | Professional & scientific | 2020 |
| LIR Studio Limited | Information & communication | 2026 |
| Little Bird Told ME Ltd | Manufacturing | 2007 |
| Livdin Property Ltd | Real estate | 2018 |
| LIZ Gill Financial Solutions Ltd | Financial services | 2023 |
| LIZ Rawlinson Design Limited | Professional & scientific | 2014 |
| LIZ Turner Properties Ltd | Real estate | 2025 |
| Ljca Limited | Construction | 2015 |
| LJI Services Ltd | Wholesale & retail | 2026 |
| LJS Civils Limited | Construction | 2018 |
| Lmad Architectural Ltd | Professional & scientific | 2021 |
| Lmad Limited | Professional & scientific | 2016 |
| Lomas Investment Group Ltd | Financial services | 2023 |
| London and North Eastern Railway Limited | Other services | 2023 |
| London Lingual School Ltd | Education | 2024 |
| Longley Dairy Company | Other services | 2025 |
| Longwood Lettings Limited | Real estate | 2020 |
| Looby Loos Limited | Health & social care | 2007 |
| Lordstech Ltd | Information & communication | 2025 |
| Lower Bent Company | Other services | 2024 |
| LPJ Goya Ltd | Financial services | 2026 |
| LRE Marketing & Brand Consultancy Ltd | Professional & scientific | 2021 |
| LRU Properties Limited | Real estate | 2020 |
| Lucidian Solutions Ltd | Information & communication | 2010 |
| Lukale Associates Ltd | Construction | 1997 |
| Luxury Bedding Group Ltd | Wholesale & retail | 2019 |
| Luxury Staycations Ltd | Hospitality | 2021 |
| LVT Social Limited | Health & social care | 2025 |
| Lynora Health Ltd | Health & social care | 2025 |
| Lynton Street Limited | Real estate | 2017 |
| M & H Freehold Ltd | Construction | 2025 |
| M & M Motors (Holmfirth) LLP | | 2010 |
| M G Joinery (West Yorkshire) Limited | Construction | 2005 |
| M H W a Holdings Limited | Other services | 2023 |
| M H W a Properties Limited | Real estate | 2017 |
| M J O'Pray Ltd | Wholesale & retail | 2018 |
| M M Imports Ltd | Manufacturing | 2024 |
| M&K Minster Rental Ltd | Real estate | 2024 |
| M-Ten Ltd | Real estate | 2022 |
| M. a. Eastwood Limited | Construction | 1998 |
| Mac-Tb Enterprises Ltd | Extraterritorial | 2021 |
| Mac-Tb Ltd | Hospitality | 2021 |
| Macallan Developments Ltd | Real estate | 2025 |
| Macartney Forbes Limited | Professional & scientific | 2009 |
| Macee Group Ltd | Energy | 2026 |
| Machair Solutions Ltd | Other services | 2023 |
| Madellors Ltd | Real estate | 2023 |
| Madison Computers Limited | Real estate | 1989 |
| Magdale Accountancy Limited | Professional & scientific | 2020 |
| Magdale Testing Station Limited | Wholesale & retail | 2021 |
| Magma Ufhs Limited | Manufacturing | 2023 |
| MAI Barry Ltd | Health & social care | 2019 |
| Mainstone Carving Ltd | Construction | 2022 |
| Majestic Site Management Ltd | Construction | 2019 |
| Majestic Training Limited | Education | 2022 |
| Majlinger FEA Ltd | Professional & scientific | 2025 |
| Makarios Creations Ltd | Financial services | 2019 |
| Malcolm Sizer Planning Limited | Professional & scientific | 2002 |
| Mallin Textile Agency Limited | Wholesale & retail | 2026 |
| Malt Barn Limited | Real estate | 2008 |
| Mandara Homes Limited | Real estate | 2020 |
| Mantle Psychology Ltd | Health & social care | 2019 |
| Maple & Tweed Ltd | Wholesale & retail | 2021 |
| Marcus Hall (Properties) Limited | Construction | 2002 |
| Marioss Pizzeria Limited | Hospitality | 2025 |
| Mark Greenop Associates Ltd | Education | 2009 |
| Mark Warburton Properties LLP | | 2021 |
| Mark Williams Creative Limited | Professional & scientific | 2014 |
| Marketing Solutions 4 U Limited | Professional & scientific | 2013 |
| Marketing Yorkshire Ltd | Professional & scientific | 2024 |
| Marryat & Scott Limited | Professional & scientific | 2024 |
| Marsden IB Limited | Financial services | 2011 |
| Marshall Groundworks Ltd | Administrative & support | 2026 |
| Martin Amod Spares Limited | Manufacturing | 2012 |
| Mason & Sons Consulting Ltd | Professional & scientific | 2024 |
| Master Builders Club Franchise Ltd | Arts & recreation | 2019 |
| Master Builders Club Ltd | Arts & recreation | 2019 |
| Master Pizza & Grill Ltd | Hospitality | 2024 |
| Mastercraft Machine Tools Limited | Wholesale & retail | 2002 |
| Masterplaster (UK) Limited | Construction | 2013 |
| Masters Electrical Limited | Construction | 2007 |
| Matchless Motorcycles Limited | Manufacturing | 2019 |
| Matchmakers Recruitment Ltd | Administrative & support | 2019 |
| Matolli Limited | Wholesale & retail | 2008 |
| Matt Roberts Media and Coaching Limited | Information & communication | 2008 |
| Mayers Properties Ltd | Real estate | 2017 |
| MB Stones Ltd | Manufacturing | 2024 |
| MC and F Limited | Financial services | 2019 |
| MCG Interpreting Ltd | Professional & scientific | 2023 |
| Mcqueenacs Limited | Administrative & support | 2014 |
| MDN Construction (Yorkshire) Limited | Construction | 2016 |
| Mdtrad Limited | Manufacturing | 2011 |
| Meccano Limited | Other services | 2023 |
| Mechanical & Electrical Contracts Ltd | Construction | 2012 |
| Mechanical Bull + Limited | Manufacturing | 2025 |
| Mechanical Bull Holmfirth Ltd. | Manufacturing | 2014 |
| Media Display Screens Ltd | Wholesale & retail | 2014 |
| Media Displays Limited | Professional & scientific | 2004 |
| Mediphase Limited | Wholesale & retail | 2013 |
| Melbourne Street Management (Shipley) Limited | Households | 2011 |