| Mazatex Ltd | Other services | 2021 |
| MB Agri-Consultants Limited | Professional & scientific | 2025 |
| MB Automatic Doors Ltd. | Professional & scientific | 2022 |
| Mcclintock SRM Ltd | Administrative & support | 2015 |
| Mccormick Associates Limited | Administrative & support | 2015 |
| Mcfadden Contracting Ltd | Construction | 2019 |
| Mcfarlane Ministries Limited | Other services | 2025 |
| Mcgrane Limited | Construction | 2018 |
| Mcnaughton Machinal Ltd | Professional & scientific | 2024 |
| MCS Electrical Services Limited | Construction | 2019 |
| MCS Property Renovations Limited | Construction | 2021 |
| MCV Property Development Limited | Construction | 2020 |
| MCV Ventures Ltd | Construction | 2025 |
| MD Painting & Decorating Services Limited | Construction | 2021 |
| MDA Pubs Limited | Hospitality | 2005 |
| MDS Plumbing & Heating Ltd. | Construction | 2013 |
| MEB Validation Solutions Limited | Professional & scientific | 2025 |
| Medgenesis Limited | Information & communication | 2009 |
| Medlock River Limited | Real estate | 2024 |
| Meeds Electrical Ltd | Construction | 2021 |
| Mega Kids World Limited | Administrative & support | 2024 |
| MEI LEE Consulting Services Limited | Professional & scientific | 2026 |
| Melmont Ltd | Administrative & support | 2014 |
| Membermag Ltd | Other services | 2023 |
| Memberpulse Ltd | Other services | 2023 |
| Memdobs Limited | Health & social care | 2022 |
| Memento Studios Limited | Information & communication | 2025 |
| Mentiumuk Limited | Professional & scientific | 2024 |
| Meraki Mindset by Beth Ltd | Professional & scientific | 2020 |
| Merrick Properties Ltd | Households | 2023 |
| Metabiosis Limited | Professional & scientific | 2020 |
| Metatoken Limited | Information & communication | 2015 |
| Meze Contracting Ltd | Other services | 2023 |
| MG Engineering & Services Limited | Professional & scientific | 2014 |
| MG Property 2019 Limited | Real estate | 2019 |
| Mgkp Associates Limited | Professional & scientific | 2010 |
| Micard Industries Ltd | Information & communication | 2025 |
| Michael Murray Signs Limited | Manufacturing | 2002 |
| Mileoak Consulting Ltd | Professional & scientific | 2023 |
| Mill Straight Limited | Other services | 2016 |
| Millennium Group Holdings Ltd | Financial services | 2024 |
| Mimumu Limited | Health & social care | 2019 |
| Mindfocus Supplements Ltd | Wholesale & retail | 2025 |
| Minleon Europe Ltd | Wholesale & retail | 2026 |
| Mirassol Services Ltd | Other services | 2023 |
| Miriad FSS Ltd | Information & communication | 2010 |
| Mission Spectrum Ltd | Information & communication | 2025 |
| Mitchell TM Ltd | Construction | 2025 |
| Mitrog Ltd | Administrative & support | 2022 |
| MJ Boiler Solutions Limited | Construction | 2017 |
| MJA Maintenance Services Limited | Construction | 2025 |
| MJD Studios Limited | Arts & recreation | 2019 |
| MJG Compliance Solutions Limited | Professional & scientific | 2019 |
| MJL Motorsport Ltd. | Manufacturing | 2024 |
| Mjp.Legal Limited | Real estate | 2017 |
| MK Box Self Storage Ltd | Administrative & support | 2011 |
| Mkavs Ltd | Extraterritorial | 2021 |
| ML Ascent Limited | Real estate | 2018 |
| ML CAP Investment Limited | Administrative & support | 2024 |
| ML Equity Investment Limited | Administrative & support | 2024 |
| ML Green Investments Limited | Financial services | 2024 |
| ML Optical Services Limited | Administrative & support | 2018 |
| ML Prop Investments Limited | Real estate | 2023 |
| MLU Aesthetics Ltd | Other services | 2025 |
| Mobi Pizza Ltd | Wholesale & retail | 2024 |
| Moldova Matters Ltd | Other services | 2007 |
| MOLMAR21 Limited | Real estate | 2021 |
| Momentum Dance Events Limited | Arts & recreation | 2023 |
| Momentum Market Ltd. | Information & communication | 2022 |
| Mona Construction Ltd | Construction | 2016 |
| Mona Luxury Aesthetic Medicine Clinic Ltd | Health & social care | 2025 |
| Monimi Ltd | Wholesale & retail | 2011 |
| Morespace Storage Ltd | Transport & logistics | 2012 |
| Morris James Ltd | Professional & scientific | 2006 |
| Mortgage Front Limited | Financial services | 2025 |
| Moss UK Holdings Limited | Manufacturing | 2014 |
| Mosttik Ltd | Other services | 2018 |
| Motion Dance Academy Limited | Education | 2021 |
| Motion Media Ltd | Construction | 2004 |
| Motive Graphics Limited | Manufacturing | 2019 |
| Moto Capture Media Ltd | Information & communication | 2025 |
| Motorsense Limited | Transport & logistics | 1979 |
| Motorsport Art Collector Limited | Arts & recreation | 2015 |
| Move IT - Change IT Ltd | Administrative & support | 2022 |
| Mozion Ltd | Other services | 2018 |
| MPS Events Ltd | Administrative & support | 2022 |
| MR Mann Window Cleaning Limited | Administrative & support | 2018 |
| Mr/Co Ltd | Professional & scientific | 2025 |
| MRD Technology Limited | Professional & scientific | 2016 |
| Mrow Construction Limited | Construction | 2025 |
| MSP Estates Limited | Real estate | 2019 |
| Mtjl International Ltd | Administrative & support | 2021 |
| MTX Logistics Ltd | Transport & logistics | 2018 |
| Mucca Beef Wellingtons Limited | Manufacturing | 2020 |
| Multi Security Services Limited | Administrative & support | 2014 |
| Mumco. Ltd | Financial services | 2016 |
| Musikschule Hermine Ltd | Extraterritorial | 2021 |
| Mwcs Cambridge Ltd | Professional & scientific | 2025 |
| MWP Welding & Engineering Services Ltd. | Administrative & support | 2017 |
| My DRY Cleaners Ltd | Other services | 2025 |