| Monddi Dimond Press Ltd | Administrative & support | 2008 |
| Moneytree Financial Ltd | Professional & scientific | 2015 |
| Monitess Limited | Real estate | 2025 |
| Monolith Construction Group Ltd | Construction | 2024 |
| Montana Estates London Limited | Construction | 2022 |
| Montana Food Limited | Hospitality | 2014 |
| Montgomrey's Wharf Management Company Ltd | Households | 2023 |
| Monttaber Holdings Limited | Financial services | 2026 |
| MOO MOO Property Holdings Limited | Real estate | 2023 |
| MOO MOO Property Management Ltd | Households | 2022 |
| Moomba Events Ltd | Arts & recreation | 2024 |
| Moon Runner Digital Ltd | Information & communication | 2025 |
| Moor Place Park Management Company Ltd | Real estate | 2014 |
| Moore Accessories London Ltd | Wholesale & retail | 2020 |
| Mora High Standard Limited | Health & social care | 2021 |
| Morgan Creative Limited | Arts & recreation | 2007 |
| Morning DEW Property Investment Limited | Financial services | 2019 |
| Motivaction Consultancy Ltd | Professional & scientific | 2026 |
| Motivatin CIC | Administrative & support | 2022 |
| Motor Medics Cheshunt Limited | Wholesale & retail | 2026 |
| MOUNT41 Estates Limited | Real estate | 2023 |
| Move Studio London Ltd | Arts & recreation | 2025 |
| Mowena Ltd | Hospitality | 2025 |
| MOY Property Services Ltd | Construction | 2016 |
| MP Consultancy Group Limited | Education | 2021 |
| MP Cuffley Ltd | Real estate | 2025 |
| MPR & Associates Ltd | Transport & logistics | 2020 |
| MPS Horticultural Limited | Wholesale & retail | 2010 |
| MPW Green Scenes Ltd | Administrative & support | 2019 |
| Mrs.Blak Ltd | Wholesale & retail | 2012 |
| Msbs Group Ltd | Manufacturing | 2024 |
| MSC Clinical Specialist Consulting Ltd | Health & social care | 2025 |
| MSL Assets Ltd | Real estate | 2017 |
| MSL Holdings Limited | Professional & scientific | 2015 |
| MSO Woodland Limited | Construction | 2025 |
| MT Brickpro Ltd | Construction | 2025 |
| MTS Construction Limited | Construction | 2024 |
| Mukai Digital Ltd | Information & communication | 2020 |
| Mulberry Wills LLP | | 2025 |
| Multai Ltd | Information & communication | 2025 |
| Multiclean Services Maintenance and Repairs Limited | Administrative & support | 2012 |
| Multiple Digits Ltd | Information & communication | 2009 |
| Multiworth Limited | Real estate | 1969 |
| Munro Carpentry Ltd | Manufacturing | 2022 |
| Muraci Ltd | Construction | 2022 |
| Murati Group Ltd | Construction | 2018 |
| Murcias Finest Properties Ltd | Real estate | 2025 |
| Musa Hussain Ltd | Hospitality | 2025 |
| Mush BE Love Limited | Health & social care | 2023 |
| Music Mission Ltd | Education | 2021 |
| Musical Flow Ltd. | Real estate | 2015 |
| Musonza Ltd | Health & social care | 2017 |
| Muthabara Ltd | Real estate | 2025 |
| Muzzy Group Ltd | Construction | 2019 |
| Muzzy Haulage Ltd | Transport & logistics | 2019 |
| Muzzy LAB Supply Ltd | Wholesale & retail | 2026 |
| Mvblake Consultancy Limited | Professional & scientific | 2017 |
| My London Services Ltd | Hospitality | 2015 |
| My Photo Genie Limited | Professional & scientific | 2018 |
| My Properties (UK) Limited | Real estate | 2014 |
| MYR Estates Limited | Real estate | 2016 |
| Myra Developments Limited | Construction | 2020 |
| Myrojin Ltd | Financial services | 2022 |
| Myvon Peegee Medical Consultancy Limited | Health & social care | 2010 |
| N & E Investments Limited | Real estate | 1997 |
| N Flack Building Services Ltd | Construction | 2016 |
| N15 Waste and Recycle Ltd | Water & waste | 2024 |
| N16 Property Services Limited | Real estate | 2010 |
| N17 Handyman Ltd | Construction | 2025 |
| NAG Construction Ltd | Construction | 2017 |
| Nails Space Ltd | Other services | 2025 |
| Nala Limited | Manufacturing | 2018 |
| NAM Nails Ltd | Other services | 2017 |
| Nanak Roots Ltd | Financial services | 2025 |
| Naonath Consulting Limited | Other services | 2020 |
| NAR Development Services Limited | Construction | 2026 |
| NAS Property Investments Ltd | Real estate | 2023 |
| Naseberry Court Management Company Limited | Real estate | 2019 |
| Nash Company Admin Services Limited | Administrative & support | 2024 |
| Natalia Care Services Ltd | Health & social care | 2015 |
| Nathi Property Ltd | Real estate | 2024 |
| National Vehicle Hire Limited | Administrative & support | 2025 |
| Naturals Byyb Ltd | Other services | 2023 |
| Nature Friendly Health Limited | Health & social care | 2015 |
| Nays Foods Limited | Hospitality | 2023 |
| Naz's Property Limited | Real estate | 2025 |
| Nazeing Auto Repairs Limited | Wholesale & retail | 2024 |
| Nazeing Autos Ltd | Wholesale & retail | 2023 |
| NB Private Tuition Ltd | Education | 2026 |
| NB Rail Ltd | Construction | 2022 |
| Nbistro Ltd | Hospitality | 2023 |
| Ncommerce London Ltd | Wholesale & retail | 2023 |
| Nconwa Services Limited | Construction | 2019 |
| Nearestplane Limited | Manufacturing | 2026 |
| Neatdot Limited | Information & communication | 2021 |
| Nefsoft Ltd | Information & communication | 2020 |
| Neky Consultants Limited | Real estate | 2014 |
| Nellsar Holdings Limited | Financial services | 2026 |
| Nenik Consulting Ltd | Professional & scientific | 2018 |
| Nerdlxb Ltd | Professional & scientific | 2024 |