| Love Affiliates Ltd | Professional & scientific | 2022 |
| Love Frequency Limited | Wholesale & retail | 2024 |
| LOX Media Limited | Professional & scientific | 2019 |
| Lrdunnpropertiesltd Ltd | Households | 2025 |
| LRK Consultancy Limited | Administrative & support | 2025 |
| LS Traders (BFD) Ltd | Hospitality | 2026 |
| LTS Commerce Ltd | Information & communication | 2025 |
| Lumy Property Services Limited | Construction | 2022 |
| Luna Property Investing Ltd | Administrative & support | 2025 |
| Lusify Ltd | Construction | 2022 |
| Lutons of Baildon Limited | Transport & logistics | 2023 |
| Luvora Care Limited | Health & social care | 2025 |
| Luxe Vehicle Solutions Ltd | Wholesale & retail | 2020 |
| LWW Engineering Precision Limited | Construction | 2015 |
| Lyleburn Limited | Real estate | 2008 |
| Lyndale Hotel Limited | Hospitality | 2023 |
| Lynfield Properties Group Ltd | Real estate | 2022 |
| Lynwood 65 Limited | Wholesale & retail | 2012 |
| M a Trading Group (Yorkshire) Ltd | Wholesale & retail | 2023 |
| M D Bentley Property Services Limited | Construction | 2000 |
| M I Carz Limited | Wholesale & retail | 2012 |
| M James Commercials Ltd | Wholesale & retail | 2025 |
| M K Joinery Yorkshire Ltd | Construction | 2025 |
| M Locum Services Ltd | Other services | 2025 |
| M M Construction Services Limited | Construction | 2026 |
| M R Bakery Services Limited | Manufacturing | 2018 |
| M Richardson Process Engineering Limited | Professional & scientific | 2025 |
| M Y Courier Services (Yorkshire) Ltd | Transport & logistics | 2019 |
| M&A Yorkshire Limited | Real estate | 2021 |
| M&N Jets Ltd | Administrative & support | 2023 |
| M&S Food Solutions Ltd | Hospitality | 2024 |
| M. B. Bellmore Dormant Limited | Professional & scientific | 1977 |
| M.Evans.Dogwalking Limited | Other services | 2024 |
| M.K.M Motivation Limited | Real estate | 2014 |
| M.P.S. (Leeds) Limited | Administrative & support | 2011 |
| M4 Bar Co Limited | Hospitality | 2025 |
| Maclean & Company, Accountants Limited | Professional & scientific | 2017 |
| MAG Services Group Ltd | Professional & scientific | 2022 |
| Magellan Estates Limited | Real estate | 1998 |
| Magis Electrical Limited | Construction | 2025 |
| Magis Fire Limited | Public administration | 2025 |
| Magis Security Limited | Administrative & support | 2025 |
| MAH Optical Ltd | Wholesale & retail | 2025 |
| Mahr Holdings Ltd | Real estate | 2024 |
| Majestic Driveways Limited | Construction | 2024 |
| Make Your Furniture Ltd | Manufacturing | 2020 |
| Makeable Labs Ltd | Professional & scientific | 2025 |
| Making Your Mind UP IT Ltd | Education | 2018 |
| MAL Decorating Ltd | Construction | 2019 |
| MAL Property Solutions Limited | Construction | 2024 |
| Malli Medical Ltd | Other services | 2024 |
| Mallisam Ltd. | Real estate | 2019 |
| Malloy & Co Pubs Limited | Hospitality | 2025 |
| Malstoosch Ltd | Real estate | 2023 |
| Malt Property Developments Limited | Real estate | 2017 |
| Mango Developments Ltd | Financial services | 2023 |
| Mango Estates & Lettings Ltd | Real estate | 2023 |
| Manor Coating Systems (Holdings) Limited | Financial services | 2013 |
| Manor Coating Systems (Properties) Limited | Financial services | 2013 |
| Maple Tree Estates Investments Ltd | Real estate | 2023 |
| Maple Tree Estates Limited | Real estate | 2016 |
| Maps Villacim Limited | Real estate | 2023 |
| Maptastic Limited | Information & communication | 2022 |
| Marah Associates Limited | Administrative & support | 2024 |
| Marbec Healthcare Ltd | Health & social care | 2021 |
| March Solutions Limited | Professional & scientific | 2025 |
| Marchup House Limited | Professional & scientific | 2017 |
| Marine Valley Associates Limited | Administrative & support | 2018 |
| Marios DS Restaurant Ltd | Hospitality | 2023 |
| Mark Brearley & Company Limited | Real estate | 2020 |
| Mark Paynter (Contracts) Limited | Construction | 1986 |
| Marketing Adventures UK Ltd | Professional & scientific | 2023 |
| Marlows Development & Rentals Ltd | Real estate | 2017 |
| Maroat Ltd | Real estate | 2025 |
| Marpak Extrusions Limited | Manufacturing | 2000 |
| Marpol Construction Ltd | Construction | 2026 |
| Martial Arts Coach Limited | Administrative & support | 2015 |
| Martin Bell Electrical Limited | Construction | 2013 |
| Martinjhirst Limited | Professional & scientific | 2025 |
| MAS Scaffolding Services Limited | Construction | 2018 |
| Masala Doncaster Ltd | Hospitality | 2026 |
| Mash Architecture Interiors Ltd | Professional & scientific | 2010 |
| Mason and Rhodes Properties Limited | Real estate | 2025 |
| Masons Mickleover 55 Limited | Hospitality | 2022 |
| Massimo 5 Limited | Wholesale & retail | 2020 |
| Mastwood Properties Limited | Construction | 2002 |
| Matchgorithm Ltd | Information & communication | 2017 |
| Matthews MEE Limited | Professional & scientific | 2010 |
| Maws Craft Limited | Wholesale & retail | 2024 |
| MB Parks Limited | Construction | 2024 |
| MB Projects & Interiors Limited | Construction | 2013 |
| MB Roofing & Building Services Limited | Construction | 2023 |
| MB Storage Limited | Transport & logistics | 2025 |
| MBH Dent Ltd | Health & social care | 2025 |
| Mbsb Investments Ltd | Other services | 2025 |
| Mccarten Properties Ltd | Real estate | 2019 |
| Mcford Plumbing Ltd | Construction | 2019 |
| MCM Marketing Limited | Information & communication | 2016 |
| MCM Property Management Limited | Real estate | 2000 |
| Mcquillan Corporate Communication Limited | Professional & scientific | 2014 |