| Local Traders Publications Limited | Professional & scientific | 2015 |
| Lock Services Ltd | Construction | 2025 |
| Locum Doctor Recruitment Ltd | Other services | 2022 |
| Logic Named JOE Limited | Information & communication | 2017 |
| Logista AI Ltd | Information & communication | 2024 |
| Logistream Limited | Information & communication | 2009 |
| London First Maintenance Ltd | Construction | 2021 |
| London Livers Ltd | Health & social care | 2020 |
| London Sparx Limited | Education | 2023 |
| London Stairmasters Ltd | Construction | 2024 |
| Londonisvara Trading Co. Ltd | Wholesale & retail | 2016 |
| Lotus Consultants Limited | Construction | 2010 |
| Lotus Nine Ltd | Real estate | 2026 |
| Lowestoft Court Apartments Limited | Construction | 2019 |
| LPS Dental Limited | Health & social care | 2022 |
| LSA Care Limited | Financial services | 2023 |
| Lucas Interiors Ltd | Construction | 2017 |
| Luckinterior Ltd | Construction | 2014 |
| Luconstruct Ltd | Construction | 2016 |
| Lulutzu Ltd | Transport & logistics | 2020 |
| Lunar Event Production Ltd. | Arts & recreation | 2019 |
| Lunay Group Ltd | Financial services | 2024 |
| Lungcorp Ltd | Health & social care | 2019 |
| Lustrio Crew Ltd | Administrative & support | 2026 |
| Lutherlinks Ltd | Real estate | 2024 |
| Luxe Beauty & Aesthetics Ltd | Other services | 2022 |
| Luxe Glowez Limited | Other services | 2025 |
| Luxepopcreationsltd Ltd | Wholesale & retail | 2026 |
| Luxerise Developments Ltd | Construction | 2025 |
| Luxury Bargains Ltd | Wholesale & retail | 2025 |
| Luxury Optics Ltd | Wholesale & retail | 2021 |
| Lymore Mews Residents Association Limited | Hospitality | 2007 |
| LZ Consultants Ltd | Construction | 2021 |
| M Albulet Ltd | Construction | 2015 |
| M Glynn Limited | Other services | 2015 |
| M Heating Limited | Extraterritorial | 2022 |
| M S Geduld Associates Limited | Administrative & support | 2009 |
| M Yale Limited | Administrative & support | 2015 |
| M&A News Agents Ltd | Wholesale & retail | 2024 |
| M&B Utilities 97 Limited | Construction | 2025 |
| M&M SET Design Limited | Construction | 2013 |
| M'Nails 89 Ltd | Other services | 2025 |
| M-Training.Co.Uk Ltd | Education | 2011 |
| M. Yates Limited | Construction | 2004 |
| M.B.A. Literary Agents Limited | Information & communication | 1971 |
| M2M Cycling Ltd | Wholesale & retail | 2021 |
| Mabear Holdings Limited | Financial services | 2012 |
| Mabel's Vintage Tearooms Ltd | Hospitality | 2015 |
| Mack Scaffolding Limited | Construction | 2013 |
| Mactilney Limited | Financial services | 2024 |
| MAD. T Rigging Limited | Professional & scientific | 2017 |
| Made in Chocolate Limited | Manufacturing | 2020 |
| Magic Bathroom Ltd | Construction | 2022 |
| Magna Papers Group Ltd | Wholesale & retail | 2022 |
| Mahalakshmi Enterprises Ltd | Health & social care | 2011 |
| Makalanda Management Group LLP | | 2020 |
| Makz Talent Ltd | Information & communication | 2024 |
| MAL Projects Ltd | Construction | 2025 |
| Malthere Publications Limited | Information & communication | 2014 |
| Management Mantra Ltd | Real estate | 2022 |
| Manbert Ltd | Real estate | 2013 |
| Manchester Housing Assets Limited | Professional & scientific | 2017 |
| Mandell Consulting Limited | Financial services | 2013 |
| Manna Communion Ltd | Other services | 2022 |
| Manor View Health Limited | Health & social care | 2021 |
| Manseel Property Services Ltd | Construction | 2020 |
| MAP Freight Ltd | Transport & logistics | 2013 |
| Marina Tech Solutions Ltd | Information & communication | 2022 |
| Marinat Properties Limited | Real estate | 2006 |
| Mariusmatei Ltd | Construction | 2016 |
| Mark Donald Ltd | Information & communication | 2018 |
| Marklark Limited | Real estate | 1987 |
| Marks Consulting Partners Limited | Administrative & support | 2015 |
| Markscp Holdings Limited | Administrative & support | 2024 |
| Martam Services Limited | Real estate | 2004 |
| Martelbrynic Media Limited | Information & communication | 2017 |
| Maruti Logistic Limited | Professional & scientific | 2018 |
| Masai Group Limited | Real estate | 2018 |
| Masai Ltd | Wholesale & retail | 2018 |
| Mash Enterprises Limited | Manufacturing | 1986 |
| Masmin Limited | Real estate | 2024 |
| Master Glass & Windows Ltd | Manufacturing | 2021 |
| Masterbuild Building Services Ltd | Construction | 2024 |
| Mastersingers (1998) Limited | Arts & recreation | 1998 |
| Masti Entertainment UK Limited | Information & communication | 2023 |
| Match My Office Limited | Real estate | 2025 |
| Matchstick Associates Ltd | Administrative & support | 2019 |
| Materia Products Manufacturing Limited | Administrative & support | 2018 |
| Materium Connect Limited | Professional & scientific | 2023 |
| Mathuram Ltd | Real estate | 2024 |
| Matt Payne Electrical Ltd | Construction | 2015 |
| Mavencia Ltd | Professional & scientific | 2022 |
| Maxfac Surgical Ltd | Other services | 2013 |
| Mayar Motors Ltd | Administrative & support | 2026 |
| Mayflower Removals Limited | Transport & logistics | 2025 |
| Mayflower Security Systems Limited | Administrative & support | 2022 |
| Mayur Enterprises Limited | Wholesale & retail | 2014 |
| MAZ Global Ltd | Wholesale & retail | 2021 |
| MB Optical Limited | Wholesale & retail | 2012 |
| Mcalynn Construction Ltd | Construction | 2023 |