| Lion Lock Limited | Hospitality | 2018 |
| Lionz DEN Gym Ltd | Arts & recreation | 2020 |
| Liquid Fabrications Limited | Manufacturing | 2019 |
| Little and Large Catering Ltd | Hospitality | 2024 |
| Little Earthlings Ltd | Wholesale & retail | 2025 |
| Local Friendly Plumber Ltd | Construction | 2021 |
| Lockdown Events Ltd | Arts & recreation | 2022 |
| Lockmasters Midlands Ltd | Professional & scientific | 2025 |
| Lodge 17 Ltd | Hospitality | 2026 |
| Lofty Lifting Services Ltd | Wholesale & retail | 2021 |
| Lofty Property Holdings Ltd | Real estate | 2024 |
| London & Home Counties Shop Holdings Limited | Real estate | 1939 |
| London Road Valeting Centre Ltd | Administrative & support | 2016 |
| Long Furlong Farm Wedding & Events Ltd | Arts & recreation | 2016 |
| LOW March Investments Limited | Extraterritorial | 2024 |
| LR SS UK Ltd | Hospitality | 2024 |
| Lr-Man Limited | Administrative & support | 2021 |
| Ltautodiagnostics Ltd | Wholesale & retail | 2025 |
| Lucautotrade Ltd | Wholesale & retail | 2025 |
| Lucidity IP Ltd | Professional & scientific | 2022 |
| Luma Leadership Development Ltd | Professional & scientific | 2025 |
| Lumena Lights Ltd | Wholesale & retail | 2009 |
| Luminlayer Technologies Ltd | Information & communication | 2026 |
| Lumix Group Ltd | Professional & scientific | 2024 |
| Lunabee Limited | Transport & logistics | 2025 |
| Lyte Coatings Limited | Energy | 2021 |
| M C T Engineering Limited | Manufacturing | 1995 |
| M Crumpton Builders Limited | Construction | 2010 |
| M Davies Limited | Construction | 2003 |
| M P Clarke Construction Limited | Administrative & support | 2013 |
| M R Transport Ltd | Transport & logistics | 2019 |
| M. Keenan Construction Ltd | Construction | 2023 |
| M.F. Penning Limited | Arts & recreation | 2004 |
| Mackenzie Business Development Limited | Construction | 2003 |
| Macson Engineering Limited | Manufacturing | 2019 |
| MAD Collective Ltd | Wholesale & retail | 2021 |
| Madfly Limited | Administrative & support | 2007 |
| Madsie Investments Ltd | Real estate | 2022 |
| Maghaus Studio Ltd | Professional & scientific | 2025 |
| Maharajah Bar & Lounge Ltd | Hospitality | 2025 |
| Main Line Timber (Holdings) Limited | Financial services | 2015 |
| Main Line Timber Limited | Manufacturing | 1988 |
| Maineford Ltd | Professional & scientific | 2014 |
| MAK Jobs Ltd | Administrative & support | 2019 |
| Malcam Ltd | Transport & logistics | 2024 |
| Malexi Ltd | Transport & logistics | 2023 |
| Malo Events Europe Limited | Other services | 2016 |
| Malo Events Limited | Other services | 2017 |
| Mama African Limited | Administrative & support | 2017 |
| Mambo Global Ltd | Manufacturing | 2024 |
| Mancain Limited | Hospitality | 2026 |
| Manhaus Ltd | Other services | 2010 |
| Manor Farm Day Care Ltd | Health & social care | 2022 |
| Manor Way Limited | Other services | 2025 |
| Manorial Counsel Limited | Professional & scientific | 2013 |
| Manualcpd Ltd | Information & communication | 2026 |
| Manyatta Limited | Wholesale & retail | 2014 |
| March Projects Developments Limited | Construction | 2016 |
| Marcin Drabinowicz Support Fair Exhibitors Ltd | Transport & logistics | 2013 |
| Marconi Electronics Ltd | Professional & scientific | 2024 |
| Marconti Ltd | Transport & logistics | 2022 |
| Mardi Gras Motorsport Limited | Wholesale & retail | 1992 |
| Margo and Evie Vintage Ltd | Wholesale & retail | 2020 |
| Maria Addison Ltd | Extraterritorial | 2024 |
| Maria Ltd | Transport & logistics | 2023 |
| Marine Hygiene Limited | Wholesale & retail | 2020 |
| Mario Transport Ltd | Transport & logistics | 2010 |
| Mark Rathore PSC Limited | Professional & scientific | 2021 |
| Marker Hospitality Ltd | Hospitality | 2025 |
| Marketing With Ethics Ltd | Professional & scientific | 2016 |
| Marlborough Furniture Surfaces Limited | Professional & scientific | 2003 |
| Marnic Property Limited | Professional & scientific | 2005 |
| Mars Healthcare Solutions Ltd. | Transport & logistics | 2015 |
| Mars Optical Limited | Wholesale & retail | 2009 |
| Marshall Marine Contracting Ltd | Manufacturing | 2020 |
| Marsovszki Ltd | Transport & logistics | 2018 |
| Martins Performing Arts Limited | Arts & recreation | 2025 |
| Marvel Maintenance Ltd | Construction | 2025 |
| Masada Lifting Industry Co., Ltd | Professional & scientific | 2015 |
| Masalla Curry House Limited | Hospitality | 2023 |
| Massage Guru Limited | Other services | 2022 |
| Matosza Ltd | Transport & logistics | 2016 |
| Matrix Secretaries Limited | Professional & scientific | 2005 |
| Matt and Gloss Designs Ltd | Manufacturing | 2002 |
| Mattcallaghan Motorsport Design Ltd | Professional & scientific | 2022 |
| Maxwell Optics Ltd | Wholesale & retail | 2015 |
| Mayfair Clean Care Ltd | Administrative & support | 2012 |
| Maylin Associates Limited | Real estate | 2009 |
| Mazpro Ltd | Public administration | 2026 |
| MAZPRO12 Limited | Health & social care | 2019 |
| MC Gibb Ltd | Wholesale & retail | 2024 |
| Mccarthy Decorating Ltd | Construction | 2023 |
| Mckilnerhone Ltd. | Administrative & support | 2011 |
| MD Investgroupp Ltd | Construction | 2018 |
| Md&A Construction Ltd | Construction | 2022 |
| MDT Logistics Solutions Ltd | Administrative & support | 2017 |
| ME Wright Holdings Limited | Financial services | 2013 |
| Meatgold Beef Limited | Agriculture & fishing | 2021 |
| MEC & Associates Limited | Professional & scientific | 2014 |
| Mecpro GB Limited | Wholesale & retail | 2021 |