| Lofe Properties Ltd | Real estate | 2025 |
| Log-It Shop Limited | Wholesale & retail | 2023 |
| Lolar Limited | Real estate | 2017 |
| London & Lincolnshire Investments Limited | Real estate | 1993 |
| London Pattu Ltd | Wholesale & retail | 2025 |
| Londonthorpe Construction Limited | Real estate | 1997 |
| Londonthorpe Property Ltd | Real estate | 2000 |
| Long Meadow (Sudbrook) Management Co Limited | Real estate | 2006 |
| Long ROW Consulting Limited | Professional & scientific | 2021 |
| Long Wittenham Ltd | Transport & logistics | 2022 |
| Looporder Limited | Transport & logistics | 1987 |
| Lorienne Limited | Households | 2015 |
| Lotsie Ltd | Information & communication | 2026 |
| Loughkillygreen Ltd | Administrative & support | 2021 |
| Love Construction Limited | Construction | 2005 |
| Love Forever Ltd | Professional & scientific | 2025 |
| Loveden Estates (Dawsmere) Limited | Agriculture & fishing | 2016 |
| Loveden Estates Limited | Financial services | 2018 |
| Lower Sturthill LLP | | 2006 |
| Lowkee Living Ltd | Households | 2021 |
| LR Nexus Consultancy Ltd | Professional & scientific | 2026 |
| LR Rogers Property Ltd | Real estate | 2017 |
| LRT Consulting Limited | Professional & scientific | 2024 |
| Lucky Nails 99 Ltd | Other services | 2025 |
| Ludgate Resources Limited | Financial services | 2021 |
| Lulu’S Hair & Beauty Ltd | Other services | 2026 |
| Lumley Farming Company Limited | Agriculture & fishing | 2022 |
| Lumous Properties Ltd | Real estate | 2025 |
| Luna RAY Events Ltd | Professional & scientific | 2018 |
| Lunn & Partners Contracting Ltd | Manufacturing | 2002 |
| Lutine Luncheon Club Limited | Other services | 2017 |
| Lxfoodcraft Ltd | Hospitality | 2025 |
| Lygean Finance Limited | Financial services | 2011 |
| Lykke Venues Limited | Hospitality | 2020 |
| Lymington Underwriting Limited | Financial services | 2001 |
| M & B Sacks Limited | Manufacturing | 1981 |
| M & G Mobile Home Sales Ltd | Wholesale & retail | 2019 |
| M a Scott Plumbing & Heating Limited | Construction | 2018 |
| M Brentley Heating Limited | Construction | 2007 |
| M H Chatterton Limited | Financial services | 2025 |
| M K Mobile Refinishing Limited | Wholesale & retail | 2017 |
| M Kara Building Services Ltd | Construction | 2023 |
| M Kara Investments Limited | Real estate | 2025 |
| M Naylor Consulting Limited | Professional & scientific | 2017 |
| M Planning and Design Limited | Professional & scientific | 2025 |
| M S Herbert Limited | Real estate | 2014 |
| M W Monks Limited | Professional & scientific | 2024 |
| M Watson Construction (2010) Limited | Construction | 2010 |
| M Watson Construction Limited | Construction | 2005 |
| M&G Group Europe Ltd | Wholesale & retail | 1993 |
| M&J Van Logistics Ltd | Transport & logistics | 2018 |
| M&L Law Holdings Limited | Financial services | 2022 |
| M&L Law Properties Limited | Real estate | 2022 |
| M&M Willett Homes Ltd | Construction | 2020 |
| M&M Willett Properties Ltd | Construction | 2026 |
| M. Hulett Garden Services Limited | Construction | 2020 |
| M.D.K Builders Ltd | Construction | 2022 |
| MA Co GA Ltd | Households | 2025 |
| Maceo Design and Management (GB) Ltd | Professional & scientific | 2010 |
| MAD Philomena Ltd | Professional & scientific | 2015 |
| MAD Textiles Limited | Manufacturing | 2009 |
| Madigan-Hughes Property Ltd | Real estate | 2020 |
| Magentis Publishing Ltd | Information & communication | 2026 |
| Magic Bore Ltd | Manufacturing | 2019 |
| Magna Heating Ltd | Construction | 2022 |
| Magpie Underwriting LLP | | 2008 |
| Mahalakshmi Karri Ltd | Health & social care | 2019 |
| Maidenhouse Limited | Agriculture & fishing | 2013 |
| Mainstay Support Services Ltd | Professional & scientific | 2020 |
| Majestic Joinery Ltd | Manufacturing | 2019 |
| MAK Smile Services Ltd | Health & social care | 2022 |
| Making Headspace Ltd | Administrative & support | 2009 |
| Mako VET Ltd | Professional & scientific | 2026 |
| Makshal Limited | Public administration | 2022 |
| Malinka Market Limited | Wholesale & retail | 2017 |
| Malones Accounting Limited | Professional & scientific | 2024 |
| Malones Business Services Limited | Professional & scientific | 2026 |
| Mandarin Chinese Takeaway Ltd | Hospitality | 2025 |
| Manili Transport Ltd | Transport & logistics | 2016 |
| Mann Projects Ltd | Construction | 2016 |
| Mannakin Ltd | Agriculture & fishing | 2008 |
| Manor Barns Management Limited | Hospitality | 2005 |
| Manor Croft Residents Company Limited | Households | 2007 |
| Manor Farm Tree Services Limited | Agriculture & fishing | 2018 |
| Manor Farms (North Witham) | Agriculture & fishing | 1948 |
| Mantels Limited | Manufacturing | 2007 |
| Manthorpe Construction Limited | Construction | 2001 |
| Manthorpe Furniture Ltd | Other services | 2019 |
| Maplebrook Construction Ltd | Construction | 2024 |
| Maplebrook Lettings Ltd | Real estate | 2025 |
| Mapps 418 LLP | | 2007 |
| Marast Ltd | Real estate | 2020 |
| Marcus Wilkinson Clocks Ltd | Wholesale & retail | 2011 |
| Mardleybury Underwriting LLP | | 2009 |
| Mardleybury USD Limited | Financial services | 2022 |
| Mari Spotless Services Limited | Administrative & support | 2025 |
| Marigolds Cleaning & Gardening Services Ltd | Households | 2012 |
| Mariopol Ltd | Transport & logistics | 2016 |
| Mark Bates Limited | Financial services | 1994 |
| Mark Hickling Ltd | Transport & logistics | 2014 |