| Lotos Vehicle Management Limited | Wholesale & retail | 2019 |
| Loucos Estates Ltd | Real estate | 2022 |
| Loughkei Ventures Ltd | Information & communication | 2024 |
| Louis Byrne Real Estate Ltd | Real estate | 2023 |
| Louis Carlsen Build & Renovation Limited | Construction | 2020 |
| Loup Architecture Limited | Professional & scientific | 2020 |
| Love My Planet Limited | Arts & recreation | 2006 |
| Lovin Films Pro Ltd | Information & communication | 2023 |
| Lower Farm (Windsor) Management Company Limited | Households | 1996 |
| Lowgate Property Management Limited | Real estate | 1982 |
| Lowjamz* Ltd | Arts & recreation | 2024 |
| LPM Property Services Limited | Real estate | 2016 |
| Lred Consultancy Services Limited | Professional & scientific | 2023 |
| Lred Group Holdings Ltd | Financial services | 2026 |
| LS Neurodiversity Services Ltd | Health & social care | 2023 |
| LSB Props Ltd | Administrative & support | 2022 |
| LSM Global Limited | Professional & scientific | 2014 |
| Lucid Asset Investments Limited | Real estate | 2018 |
| Lucid Communications Limited | Information & communication | 2002 |
| Lucidity London Limited | Professional & scientific | 2015 |
| Lucky Star Car Hire Ltd | Administrative & support | 2017 |
| Lucy Higginson Ltd | Information & communication | 2015 |
| LUD Ltd | Administrative & support | 2013 |
| Lukaszdtrans Ltd | Transport & logistics | 2023 |
| Lullymore Properties Limited | Real estate | 2023 |
| Lulu Stripe Limited | Wholesale & retail | 2022 |
| Lulu's Cafe and Patisserie Ltd | Wholesale & retail | 2025 |
| Lumina Comms Ltd | Professional & scientific | 2024 |
| Luna Bella Properties Limited | Real estate | 2022 |
| Luna Gray Trades Limited | Other services | 2025 |
| LUX Fashions Ltd | Wholesale & retail | 2023 |
| LUX Homes Developments Ltd | Construction | 2019 |
| Luxe Flowers Limited | Wholesale & retail | 2013 |
| Luxelist Concierge Limited | Arts & recreation | 2009 |
| Luxnest Property Ltd | Real estate | 2024 |
| Luxostore Ltd | Wholesale & retail | 2025 |
| Luxtract Ltd | Construction | 2025 |
| Luxury Executive Cars Ltd | Transport & logistics | 2019 |
| Luxury Living Space Ltd | Transport & logistics | 2024 |
| Lydos Consultancy Limited | Professional & scientific | 2025 |
| Lyndhurst Fish Bar Ltd | Hospitality | 2019 |
| Lynton House Management Company Limited | Households | 1964 |
| Lysande Ventures Ltd | Professional & scientific | 2022 |
| M & K Davis Services Limited | Construction | 2019 |
| M and M Corporate Services Ltd | Construction | 2025 |
| M Church Carpentry Ltd | Information & communication | 2021 |
| M D West Building Services Ltd | Construction | 2026 |
| M J Wyatt Heating Ltd | Construction | 2017 |
| M T Manganelli Limited | Construction | 2002 |
| M&F Property Group Ltd | Real estate | 2023 |
| M&Sk Limited | Education | 2025 |
| M.B.S. Fabrics Limited | Wholesale & retail | 1973 |
| MA Management Group Ltd | Professional & scientific | 2020 |
| MA Teachings Ltd | Education | 2022 |
| Mabiko Intergrated Arts Ltd | Arts & recreation | 2018 |
| MAC & BEC Services Ltd | Construction | 2024 |
| Macer Medical Ltd | Administrative & support | 2020 |
| Madbird Limited | Real estate | 2016 |
| Magic Cat Records Limited | Information & communication | 2011 |
| Magic Connect Limited | Administrative & support | 2025 |
| Magic Transport Services (UK) Ltd | Transport & logistics | 2017 |
| Magicwire Limited | Wholesale & retail | 2016 |
| Mahakali MAA Limited | Real estate | 2024 |
| Maia Homes Ltd | Real estate | 2024 |
| Maid 2 Clean West Berkshire Limited | Administrative & support | 2011 |
| MAID2CLEAN Maidenhead and Bracknell Limited | Administrative & support | 2011 |
| MAID2CLEAN Reading & Wokingham Ltd | Other services | 2013 |
| Maiden Autoparts Ltd | Wholesale & retail | 2025 |
| Maidenhead and Ascot Accountancy Limited | Extraterritorial | 2006 |
| Maidenhead Pawn Ltd | Wholesale & retail | 2025 |
| Mailinglistsxpress UK Limited | Professional & scientific | 2018 |
| Main Raid Technologies Limited | Professional & scientific | 2012 |
| Maison Meejana Ltd | Hospitality | 2024 |
| Majestic Car Sales Ltd | Wholesale & retail | 2025 |
| Majestic Corp Ltd | Professional & scientific | 2023 |
| Majestic Drive Limited | Transport & logistics | 2024 |
| Majestic MED Ltd | Health & social care | 2024 |
| Majolica Hair Limited | Other services | 2019 |
| Major Immigration Services Ltd | Professional & scientific | 2016 |
| Makeoffer Limited | Wholesale & retail | 2009 |
| Maldec Holdings Ltd | Financial services | 2024 |
| Maldec Property Knolewood Ltd | Real estate | 2023 |
| Maldec Property Limited | Real estate | 2013 |
| Maldec Property Nottingham Ltd | Real estate | 2025 |
| Maldec Property Stables Limited | Hospitality | 2021 |
| Mallaby Carter Ltd | Administrative & support | 2022 |
| Manaccom UK Ltd. | Hospitality | 2026 |
| Manchester Oxford Street Hotel Opco Limited | Hospitality | 2018 |
| Manhattan Music Ltd | Arts & recreation | 2008 |
| Manifest Media Ltd | Professional & scientific | 2020 |
| Manley Restorations Limited | Administrative & support | 2004 |
| Manning & Boyce Coachworks Ltd | Wholesale & retail | 2021 |
| Manning Building & Developments Limited | Construction | 2013 |
| Manning Surgical Limited | Wholesale & retail | 2023 |
| Manningviney Limited | Health & social care | 2019 |
| Maple (357) Limited | Households | 2010 |
| Maple Assets Ltd | Real estate | 2023 |
| Maple Court (Eton Wick) Limited | Households | 1992 |
| Maplewood Court (Ashford) Residents Management Company Limited | Households | 2012 |
| Marai Services Ltd | Information & communication | 2026 |