| Masked Ltd | Information & communication | 2025 |
| Masoudi Ltd | Hospitality | 2012 |
| Matwad Ltd | Health & social care | 2021 |
| MAX Abraham (Roofing Contractors) Limited | Construction | 1972 |
| MAY Travel Ltd | Administrative & support | 2025 |
| Mayevelyne Interiors Ltd | Manufacturing | 2017 |
| Mazinani Capital Limited | Wholesale & retail | 2021 |
| MB Sections Limited | Manufacturing | 2014 |
| MBR Electrical Limited | Construction | 2025 |
| MBW (Yorkshire) Transport Ltd | Transport & logistics | 2011 |
| MC Controls Limited | Manufacturing | 2014 |
| MC Roofing Services Ltd | Construction | 2025 |
| Mccj Ltd | Transport & logistics | 2025 |
| Mcgavigan Corporate Limited | Professional & scientific | 2017 |
| Mcgavigan Holdings Limited | Professional & scientific | 2017 |
| MCI Transport Ltd | Transport & logistics | 2021 |
| MCM Commercial Developments Limited | Construction | 2018 |
| MDH Consultancy Solutions Limited | Professional & scientific | 2022 |
| MDH Design Studio Limited | Professional & scientific | 2023 |
| Mediterraneo Greco Ltd | Hospitality | 2026 |
| Medmec Limited | Construction | 2018 |
| Melanie's Florist Limited | Wholesale & retail | 2022 |
| Melanies Helping Hands Ltd | Health & social care | 2025 |
| Messenger Direct Limited | Information & communication | 1998 |
| Metal Depot Limited | Manufacturing | 2014 |
| Metalbybrian Limited | Manufacturing | 2023 |
| Methley Bridge Boatyard Limited | Manufacturing | 2011 |
| Methley Field Sports Limited | Arts & recreation | 2020 |
| Mezge 69 Limited | Transport & logistics | 2014 |
| MG Watch’S Ltd | Wholesale & retail | 2025 |
| MGV Auto Spares Limited | Water & waste | 2013 |
| Mhizha & Co Ltd | Wholesale & retail | 2025 |
| Michelle Larkin Consultancy Ltd | Professional & scientific | 2020 |
| Mick Thorpe & SON Ltd | Construction | 2024 |
| Midas Touch Powder Coatings Ltd | Construction | 2021 |
| Middleton Heating & Contractors Ltd | Manufacturing | 2023 |
| Mihai Vaduva Ltd | Transport & logistics | 2025 |
| MIK Trans Ltd | Transport & logistics | 2018 |
| Mike Grinch Publishing Ltd | Information & communication | 2025 |
| Mill Lane Lift Holdings Ltd | Financial services | 2021 |
| Mill Lane Lift Services Limited | Manufacturing | 2011 |
| Mill Tech Limited | Manufacturing | 2025 |
| Millees Ltd | Wholesale & retail | 2022 |
| Miracle Healthcare Recruitment Ltd | Health & social care | 2019 |
| Mirror Properties Limited | Hospitality | 2014 |
| MJ Plant Hire Yorkshire Limited | Administrative & support | 2017 |
| MK Accident Repair Specialists Ltd | Wholesale & retail | 2010 |
| MK Power Plant Services Limited | Professional & scientific | 2026 |
| MKC (Yorkshire) Limited | Financial services | 2012 |
| MKR Couriers Ltd | Transport & logistics | 2020 |
| MKR Transport Consultancy Ltd | Transport & logistics | 2024 |
| MLP Property Ventures Ltd | Real estate | 2024 |
| MO Fade Barber Limited | Other services | 2024 |
| Mobiles Expert Ltd | Wholesale & retail | 2017 |
| Mobius Edge Ltd | Professional & scientific | 2026 |
| Modern Concepts Consulting Ltd | Professional & scientific | 2013 |
| Monarch City Living Limited | Construction | 2005 |
| Monika Polish Food Ltd | Wholesale & retail | 2024 |
| Monster Lettings Ltd | Real estate | 2016 |
| Moonlite Care Ltd | Health & social care | 2023 |
| Moorhouse Opticians Limited | Health & social care | 1950 |
| Moreby Hall Houses Management Company Limited | Real estate | 2023 |
| Morta Management Ltd | Real estate | 2018 |
| Morvexs Tech Limited | Wholesale & retail | 2025 |
| Motor Source UK Limited | Administrative & support | 2017 |
| MPH Maintenance Limited | Construction | 2009 |
| MPS Care Services Ltd | Health & social care | 2022 |
| MR Protein's Ltd | Hospitality | 2024 |
| MS Endoscopy Ltd | Health & social care | 2014 |
| MSH Consulting Services Limited | Professional & scientific | 2026 |
| MSJ Management Investments Ltd | Professional & scientific | 2022 |
| MSJ Management Solutions Ltd | Professional & scientific | 2025 |
| MSW Sports Limited | Wholesale & retail | 2015 |
| Mtpooltablerecovers Limited | Arts & recreation | 2025 |
| MTW Investments Ltd | Real estate | 2024 |
| Munday Training Services Limited | Education | 2025 |
| MVS Sports and Suvs Ltd | Wholesale & retail | 2024 |
| MW Plant & Fleet Services Limited | Manufacturing | 2026 |
| MWA Fencing Limited | Construction | 2015 |
| My Goals Media Ltd | Administrative & support | 2018 |
| My Pharmacy Online UK Ltd | Wholesale & retail | 2020 |
| MZ Cars (Yorkshire) Ltd | Other services | 2026 |
| MZ Cars York Ltd | Wholesale & retail | 2021 |
| N & G Limited | Professional & scientific | 2026 |
| N & K Ferguson Properties Limited | Real estate | 2024 |
| N Fisher Services Ltd | Construction | 2026 |
| N.G.F. Industrial Doors Limited | Manufacturing | 1998 |
| NAD Construction North Ltd | Construction | 2022 |
| Nanking Takeaway Castleford Ltd | Hospitality | 2022 |
| NAS’ Convenience Store Ltd | Wholesale & retail | 2024 |
| Nationwide Business Consultancy Limited | Real estate | 2022 |
| Nationwide Business Sales Limited | Wholesale & retail | 2021 |
| Nationwide Cars & Vans Ltd | Wholesale & retail | 2025 |
| Nationwide Sales Limited | Administrative & support | 2025 |
| Nationwide Specialist Services Limited | Professional & scientific | 2018 |
| Natures Heritage Limited | Manufacturing | 2023 |
| Nauthiz Technologies Limited | Information & communication | 2003 |
| NDG Engineering Ltd | Wholesale & retail | 2025 |
| NDM Services (Yorkshire) Limited | Construction | 2015 |
| NEO Property Solutions Limited | Construction | 2007 |