| Loverseed Consulting Ltd | Financial services | 2016 |
| Lower Norton Farms Limited | Agriculture & fishing | 2011 |
| LR Aesthetics Ltd | Other services | 2024 |
| LR Coaching Ltd | Education | 2026 |
| LRC Transport Ltd | Transport & logistics | 2009 |
| LS Choules Limited | Water & waste | 2016 |
| Ltjl Limited | Information & communication | 2020 |
| LTR Innovations Ltd. | Professional & scientific | 2023 |
| LTS Removals Ltd | Transport & logistics | 2024 |
| Luce Family Investment Ltd | Other services | 2017 |
| Lucky Clover (Property) Limited | Real estate | 2021 |
| Lucky Dragon Takeaway Limited | Hospitality | 2024 |
| Lucy Rose Ltd | Administrative & support | 2015 |
| Luka Investments Limited | Financial services | 2025 |
| Luke Huckle Video Ltd | Information & communication | 2019 |
| Luken Beck MDP Limited | Professional & scientific | 2011 |
| Lukmore Mcilroy Limited Partnership | | 2002 |
| LUM Electric Technology UK Ltd | Wholesale & retail | 2024 |
| Lumi Accountancy Limited | Professional & scientific | 2026 |
| Lumify Creative Limited | Information & communication | 2017 |
| Luminary Leaders Limited | Education | 2022 |
| Lumivera Coaching & Consulting Limited | Education | 2024 |
| Luna & Associates Ltd | Information & communication | 2023 |
| Lunar Shutters Ltd | Wholesale & retail | 2023 |
| Luntz Limited | Information & communication | 2015 |
| Lunways Construction Ltd | Construction | 2006 |
| Lush Cleaning Group Ltd | Administrative & support | 2023 |
| Lush Electrical Limited | Extraterritorial | 2017 |
| Lush Group Limited | Financial services | 2017 |
| Lush Mechanical Limited | Construction | 2012 |
| Lush Properties (Southern) Limited | Real estate | 2013 |
| Lushill Habitat Limited | Professional & scientific | 2024 |
| Lutine Group Ltd | Professional & scientific | 2018 |
| Lutton Developments Limited | Real estate | 2015 |
| Lutton Properties Limited | Real estate | 2015 |
| Luxure Roofing Ltd | Construction | 2025 |
| LVC Solutions Ltd | Wholesale & retail | 2025 |
| Lwjk Ltd | Information & communication | 2025 |
| Lwse Ltd | Health & social care | 2026 |
| Lycroft Farm Limited | Agriculture & fishing | 2016 |
| Lydia Morton Aesthetics Ltd | Health & social care | 2024 |
| Lyle Radiology Limited | Health & social care | 2019 |
| Lymphatics by LIV Ltd | Other services | 2025 |
| Lynette Eastman Associates Ltd | Professional & scientific | 2010 |
| Lyra Greenhouse GAS Reduction LLP | | 2005 |
| M & B Sporting LLP | | 2013 |
| M & M'S Metalwork Limited | Manufacturing | 2004 |
| M & V Farming Limited | Agriculture & fishing | 2010 |
| M Consulting & Architecture Ltd | Information & communication | 2023 |
| M Finance Limited | Financial services | 2009 |
| M J Gill-Dougherty Ltd | Information & communication | 1999 |
| M O People Limited | Administrative & support | 2011 |
| M Squared Productions Ltd | Information & communication | 2020 |
| M Willis Consultancy Limited | Wholesale & retail | 2015 |
| M&E Dent Solutions Limited | Health & social care | 2018 |
| M&P Inter Ltd | Wholesale & retail | 2023 |
| M-Ybls LLP | | 2020 |
| M.F. Broadcasting Services Ltd | Professional & scientific | 2021 |
| M.J.T. Decorating Limited | Construction | 1992 |
| M.M. Whidborne & Sons Limited | Agriculture & fishing | 1977 |
| M.P. Surveying and Energy Services Ltd | Professional & scientific | 2018 |
| M3 Maharjan Company Limited | Real estate | 2025 |
| M3JUNCTION7 Self Storage Ltd | Real estate | 2014 |
| MA & B Consulting Ltd | Wholesale & retail | 2024 |
| MAA Network Ltd | Health & social care | 2025 |
| Mackenzie Cameron Limited | Professional & scientific | 2010 |
| Mackenzie Higgs Limited | Professional & scientific | 2012 |
| Mackintosh Catering Limited | Hospitality | 1996 |
| Macks Fitness Limited | Health & social care | 2010 |
| Macnamara London Ltd | Other services | 2020 |
| Macniven Quays Limited | Real estate | 1979 |
| MAD Keen Limited | Administrative & support | 2018 |
| MAD Sauces Ltd | Manufacturing | 2025 |
| Made the Edit Limited | Wholesale & retail | 2015 |
| Madeleine Rose Finance Ltd | Financial services | 2026 |
| Madge Ltd | Information & communication | 2018 |
| Madzore Limited | Health & social care | 2021 |
| Magdalen Mews Limited | Households | 2014 |
| Magenta Accounts Limited | Professional & scientific | 2003 |
| Magenta Drinks Ltd | Wholesale & retail | 2024 |
| Magnus Paediatrics Ltd | Health & social care | 2023 |
| Magpie Inspiring Development Limited | Professional & scientific | 2018 |
| MAID2CLEAN (Isle of Wight) Ltd | Education | 2019 |
| Maids Close Management Company Limited | Households | 2014 |
| Main Square (Bagshot) Limited | Real estate | 2006 |
| Main Square (Brinkworth) Ltd | Construction | 2022 |
| Main Square (Finance) Limited | Administrative & support | 2008 |
| Mainplan Financial Limited | Financial services | 2021 |
| Maintain Property Maintenance Limited | Administrative & support | 2019 |
| Mainza Care Services Limited | Health & social care | 2021 |
| Majara Group Ltd | Real estate | 2026 |
| Majcare Limited | Health & social care | 2020 |
| Makappen Limited | Information & communication | 2019 |
| Make IT Amazing Ltd | Manufacturing | 2021 |
| Make IT Properties Ltd | Households | 2020 |
| Make Life Simple Ltd | Other services | 2014 |
| Make My Trail Ltd | Extraterritorial | 2004 |
| Makkel Ltd | Real estate | 2022 |
| Malden and Coombe Estates Successors Limited | Other services | 1981 |
| Malden Mitcham Properties Limited | Real estate | 1934 |