| Legit Rainbow Ltd | Information & communication | 2024 |
| Leighton Plumbing and Heating Ltd | Construction | 2023 |
| Lets Talk Rubbish Waste Management and Maintenance Solutions Ltd | Water & waste | 2024 |
| Lifevision Consulting Ltd | Other services | 2024 |
| Linillo Ltd | Information & communication | 2026 |
| Link Connectivity Limited | Information & communication | 2018 |
| Lisa Nell Consulting Ltd | Professional & scientific | 2021 |
| Lishman Group Limited | Real estate | 2018 |
| Lithiumrec Ltd | Water & waste | 2025 |
| Litigation Costs Services Ltd | Professional & scientific | 2004 |
| Little Kimble Consulting Limited | Professional & scientific | 2012 |
| Livingstone Audio Visual Ltd | Construction | 2024 |
| Local Car and Van Leasing Limited | Extraterritorial | 2008 |
| Local Car and Van Rental Limited | Wholesale & retail | 2006 |
| Local Vehicle Transport Limited | Transport & logistics | 2017 |
| Locality I.T. Services Limited | Information & communication | 2010 |
| Lodestone Solutions Limited | Professional & scientific | 1990 |
| Lomoco Properties Ltd | Real estate | 2025 |
| London Leader (NO.24) Ltd | Wholesale & retail | 2025 |
| Longfox Limited | Financial services | 2022 |
| Longwick Business Solutions Ltd | Professional & scientific | 2012 |
| Loom & Grid Ltd | Information & communication | 2026 |
| LRA Services Ltd | Professional & scientific | 2018 |
| Lucolimil Limited | Information & communication | 2019 |
| Ludmac Limited | | 1984 |
| Luke Clarke Plumbing Limited | Construction | 2021 |
| Lumia I.S Ltd | Construction | 2014 |
| M Solman Project Management Limited | Construction | 2009 |
| M York Transport Limited | Transport & logistics | 2006 |
| M. J. H. Services Bucks Ltd. | Wholesale & retail | 1994 |
| Mackenzie Contracts & Design Limited | Extraterritorial | 2009 |
| Make Promotion Simple Limited | Manufacturing | 2015 |
| Make-It Design Limited | Information & communication | 2010 |
| Malro Plastics Limited | | 1985 |
| Mandeville Care Services Limited | Health & social care | 2005 |
| Mandolyn Limited | Manufacturing | 1996 |
| Manford Securities & Estates Limited | Wholesale & retail | 2003 |
| Manford Securities & Investments Limited | Financial services | 1988 |
| Manford Securities Limited | Administrative & support | 1990 |
| Manor Farm Barns (Ilmer) Management Limited | Households | 2002 |
| Mapledean Consulting Limited | Professional & scientific | 2025 |
| Maps Property Limited | Real estate | 2021 |
| Margan Bespoke Limited | Manufacturing | 2016 |
| Margan Ltd | Manufacturing | 2007 |
| Mark Hale Building Services Ltd | Construction | 2021 |
| Marketing Design Plus International Ltd | Professional & scientific | 2022 |
| Marland Broadribb Limited | Arts & recreation | 2016 |
| Marzena's Hair & Beauty Studio Limited | Other services | 2012 |
| Marzena's Hair Studio Limited | Other services | 2024 |
| Mcintosh Farms Ltd | Agriculture & fishing | 2022 |
| Mcintyre Property Limited | Real estate | 2020 |
| Meadow Long Residents Limited | Households | 1989 |
| MEB (UK) Limited | Professional & scientific | 2003 |
| MEC Leisure Ltd | Wholesale & retail | 2023 |
| Medic Move Ltd | Administrative & support | 2025 |
| Membury Macadam Ltd | Manufacturing | 2021 |
| Mfab Consulting Limited | Administrative & support | 2015 |
| Micro Electronics, Limited | | 1968 |
| Miles of Smiles NB Limited | Health & social care | 2006 |
| Millbrook Homes Ltd. | Construction | 1998 |
| Millstream Walk (Colnbrook) Management Limited | Households | 1992 |
| Mind Values Leadership Limited | Professional & scientific | 2018 |
| Mirrored Memories Limited | Professional & scientific | 2018 |
| Miss Joy Limited | Real estate | 1947 |
| MJ Property Investor Ltd | Real estate | 2019 |
| MO2 Design Limited | Professional & scientific | 2012 |
| Mobility Leisure Limited | Wholesale & retail | 2022 |
| Money Matters (High Wycombe) Limited | Professional & scientific | 1998 |
| Monsta Pizza Limited | Hospitality | 2017 |
| Montgomery Court MC Limited | Real estate | 2021 |
| Moon & Daughter Limited | Wholesale & retail | 2012 |
| Morgan Frances Limited | Construction | 2017 |
| Mortimer Property Company Limited | Real estate | 2016 |
| Moss Coffee Trading Ltd | Manufacturing | 2025 |
| Moubon Brothers Ltd | Hospitality | 2026 |
| Mould Inspections Ltd | Administrative & support | 2025 |
| Mould Remediation Ltd | Construction | 2025 |
| MS8 Ltd | Other services | 2017 |
| MSI Capital Ltd. | Financial services | 2005 |
| Mulry Properties Ltd | Real estate | 2009 |
| Multiply Music Group Limited | Education | 2018 |
| Musical Mayhem UK LLP | | 2014 |
| Myfg Limited | Other services | 2023 |
| Naef Consulting Limited | Information & communication | 2015 |
| National Equine Welfare Council C.I.C. | Other services | 2014 |
| Natural Synergy Ltd | Agriculture & fishing | 1998 |
| Navigar Limited | Information & communication | 2020 |
| NC Wenda Limited | Extraterritorial | 2008 |
| Neelam Management Consultancy Limited | Professional & scientific | 2012 |
| Neil Flavelle Consulting Ltd | Professional & scientific | 2024 |
| Nesti Living Limited | Real estate | 2017 |
| Network Music Limited | Wholesale & retail | 2005 |
| Nevstone Limited | Manufacturing | 2015 |
| New Media Solutions Ltd | Information & communication | 2024 |
| New Milvus Resources Ltd | Professional & scientific | 2017 |
| Newell Projects Limited | Professional & scientific | 2010 |
| Nextgen FX Ltd | Information & communication | 2023 |
| NHI Property Limited | Real estate | 2020 |
| Nikki Cory Consulting Ltd | Professional & scientific | 2015 |
| Nitebright Limited | Wholesale & retail | 2014 |