| LWK Media Limited | Information & communication | 2023 |
| Lyberate Ltd | Information & communication | 2024 |
| Lycett Property Limited | Extraterritorial | 2019 |
| Lycett Racing Limited | Agriculture & fishing | 2018 |
| Lydon Homes Limited | Real estate | 2022 |
| Lyne Capital Limited | Real estate | 2020 |
| Lynwood House Lillington Management Co Limited | Hospitality | 1987 |
| Lynx Family Office Limited | Financial services | 2025 |
| Lyra Trans Limited | Transport & logistics | 2025 |
| Lyty Ltd | Education | 2023 |
| M & J Stevens Limited | Professional & scientific | 2019 |
| M & L Albemarle Rest Home Ltd | Health & social care | 2018 |
| M & M Transport Services Ltd | Transport & logistics | 2026 |
| M & T Midlands Developments Limited | Construction | 2018 |
| M & T Midlands Limited | Construction | 2013 |
| M a Randall Limited | Information & communication | 2015 |
| M C Carbon Ltd | Wholesale & retail | 2012 |
| M C Garden Services Limited | Administrative & support | 2004 |
| M D V Property Maintenance Limited | Construction | 2023 |
| M Dempsey Ltd | Professional & scientific | 2025 |
| M H Polo Limited | Professional & scientific | 2011 |
| M Hardy Limited | Professional & scientific | 2013 |
| M J D Treasury Solutions Limited | Professional & scientific | 2015 |
| M J Property Portfolios Ltd | Professional & scientific | 2001 |
| M J Stalker Services Ltd | Real estate | 2023 |
| M L Classics Limited | Manufacturing | 2014 |
| M N Mechanical Estimation Services Limited | Administrative & support | 2018 |
| M Ovidiu Engineering Limited | Professional & scientific | 2014 |
| M S Fitting Solutions Ltd | Manufacturing | 2008 |
| M Skelcey Building Services Limited | Professional & scientific | 2011 |
| M Swan Holdings Ltd | Real estate | 2021 |
| M.J. Timms and SON Limited | Administrative & support | 1988 |
| M.J.Roche Ltd | Professional & scientific | 2014 |
| M57 Garage Limited | Wholesale & retail | 2025 |
| MAA Sharda Infotech Limited | Information & communication | 2019 |
| MAB Properties (West Mids) Limited | Real estate | 2025 |
| MAC Land Development Limited | Construction | 2024 |
| Mac+Wood Co. Limited | Other services | 2020 |
| Macari Design Limited | Professional & scientific | 2024 |
| Macfarlane Distribution Limited | Wholesale & retail | 2023 |
| Machine Limited | Professional & scientific | 2024 |
| Machine Vision Technology Limited | Information & communication | 2000 |
| Mackbridge International Limited | Administrative & support | 2023 |
| Mackie Consultancy Services Ltd | Professional & scientific | 2024 |
| MAD Business Consultants Ltd | Professional & scientific | 2023 |
| MAD Fellows Ltd. | Information & communication | 2011 |
| Madar Consulting Ltd | Information & communication | 2012 |
| Made in India Ltd | Wholesale & retail | 2019 |
| Maerae Properties Limited | Real estate | 2026 |
| Magic Labs IT Ltd | Information & communication | 2012 |
| Maglia Nera Ltd. | Arts & recreation | 2014 |
| Magnetar Consulting Limited | Information & communication | 2015 |
| Magnom Corporation Limited | Manufacturing | 2003 |
| MAH Couriers Ltd | Transport & logistics | 2023 |
| Mahajan Holdings Ltd | Information & communication | 2024 |
| Mahajan UK Estates Ltd | Real estate | 2021 |
| Mahaveer Publishers Ltd | Information & communication | 2016 |
| Mahaveer Records Ltd | Information & communication | 2014 |
| Maia Cafe Limited | Hospitality | 2018 |
| Mainline Repairs Ltd | Wholesale & retail | 2026 |
| Mainstave Limited | Financial services | 1987 |
| Maison Raine Ltd | Manufacturing | 2023 |
| Maitek Solutions Ltd | Wholesale & retail | 2014 |
| Majoa Ltd | Information & communication | 2019 |
| Majotech Partnership Limited | Professional & scientific | 2011 |
| Make Agency Holdings Limited | Professional & scientific | 2022 |
| Make Agency Limited | Professional & scientific | 2014 |
| Make Leamington CIC | Arts & recreation | 2022 |
| Make Live Limited | Professional & scientific | 2023 |
| Making Marks Tattoo Co. Limited | Other services | 2024 |
| Malakai Property Management Limited | Real estate | 2023 |
| Malik Estates COV Ltd | Real estate | 2024 |
| Mallorca Food & Drink Ltd | Information & communication | 2017 |
| Malvern Ltd | Wholesale & retail | 2012 |
| Mam-Mooth Ltd | Wholesale & retail | 2012 |
| Mammoth Projects Limited | Professional & scientific | 2019 |
| MAN Autos Limited | Wholesale & retail | 2025 |
| Management Sanctuary Limited | Professional & scientific | 2007 |
| Manak Software Solutions Limited | Information & communication | 2014 |
| Manderley Limited | Real estate | 2015 |
| Mangata GD Ltd | Professional & scientific | 2022 |
| Mangolab Limited | Information & communication | 2006 |
| Manhat Properties Ltd | Real estate | 2020 |
| Manifest Futures Ltd | Real estate | 2024 |
| Manjo Cleaning & Maintenance Ltd | Administrative & support | 2023 |
| Manor Farm Land Limited | Real estate | 1991 |
| Manse Residence Ltd | Households | 2021 |
| Manser Ltd | Real estate | 2024 |
| Manufacture for Design Ltd | Professional & scientific | 2025 |
| Mapduce Limited | Other services | 2019 |
| Maple Kitchen 88 Limited | Hospitality | 2022 |
| Maps of the Mind Ltd. | Education | 2020 |
| Mareeba Limited | Information & communication | 2004 |
| Margaret Hall Properties Limited | Real estate | 1973 |
| Margway Limited | Extraterritorial | 2013 |
| Mari Carmen Coaching Limited | Other services | 2024 |
| Marino Service Ltd | Manufacturing | 2020 |
| Marion James Design Limited | Extraterritorial | 2005 |
| Marir Limited | Financial services | 2014 |
| Mark & Spencer Decorating Limited | Extraterritorial | 2012 |