| MT Tech Limited | Information & communication | 2003 |
| Mtab Holdings Limited | Financial services | 2017 |
| MTB Plant Services Limited | Construction | 2015 |
| MTD & SON Ltd | Administrative & support | 2020 |
| MTD Tax Accountants Ltd | Professional & scientific | 2026 |
| Mtol Ltd | Transport & logistics | 2018 |
| MTS Healthcare Limited | Administrative & support | 2023 |
| Mttaylor UK Limited | Professional & scientific | 2017 |
| MTY Enterprise Limited | Construction | 2020 |
| Mu-Easy (UK) Limited | Professional & scientific | 2012 |
| Mudlark Labs Limited | Information & communication | 2025 |
| MUH Ltd | Hospitality | 2023 |
| Muk-Movers Limited | Other services | 2016 |
| Mukash Retail Ltd | Wholesale & retail | 2024 |
| Multichoice Metals Ltd | Manufacturing | 2026 |
| MUM Life Limited | Other services | 2024 |
| Munaire Limited | Wholesale & retail | 2025 |
| Mundon House Ltd | Real estate | 2022 |
| Muniad Limited | Health & social care | 2019 |
| Murena Services Ltd | Other services | 2015 |
| Murphy Scaffolding Limited | Construction | 2022 |
| Musa Transport Ltd | Transport & logistics | 2021 |
| Muscle Recovery Ltd | Wholesale & retail | 2024 |
| Muscovadocafe Limited | Hospitality | 2023 |
| Muscovy (UK) Limited | Professional & scientific | 2007 |
| Muse (EN) Limited | Wholesale & retail | 2021 |
| Mushherby Limited | Construction | 2025 |
| Musson Grip Limited | Administrative & support | 2011 |
| Musti Services Ltd | Wholesale & retail | 2026 |
| Muswell Road Management Limited | Real estate | 2023 |
| Muttley Crew Services Ltd | Other services | 2021 |
| Mutual Estate Agents Limited | Real estate | 2007 |
| MV Homes Ltd | Real estate | 2024 |
| MWS Accountants Limited | Professional & scientific | 2024 |
| My Basildon Barbers Ltd | Other services | 2024 |
| My Icon Services Ltd | Wholesale & retail | 2026 |
| My Stay Ltd | Real estate | 2014 |
| My SUB Hub Ltd | Administrative & support | 2025 |
| Mycoproglobal Ltd | Wholesale & retail | 2023 |
| Mycrown Investments Limited | Real estate | 1999 |
| Mygivingplus Limited | Information & communication | 2024 |
| Mylifeline Care Ltd | Health & social care | 2026 |
| Mypest Ltd | Professional & scientific | 2025 |
| Myrtle Advisory Group Limited | Professional & scientific | 2024 |
| N & J Solutions (UK) Limited | Construction | 2011 |
| N C Battle Services Ltd | Construction | 2016 |
| N Davidson Building Consultants Limited | Construction | 2007 |
| N J Eyre and Sons Property Management Ltd | Real estate | 2021 |
| N N Islam Limited | Health & social care | 2012 |
| N-Spire Chauffeurs of London Ltd | Transport & logistics | 2023 |
| N-Zet Limited | Professional & scientific | 2019 |
| N.E.A. Services Ltd | Transport & logistics | 2022 |
| N.E.H Fitness Ltd | Arts & recreation | 2019 |
| N9 Construction Limited | Construction | 2011 |
| NA Properties London Ltd | Real estate | 2024 |
| NAA Builders Limited | Construction | 2017 |
| Naav Logistics Ltd | Transport & logistics | 2025 |
| NAC Consultancy Services Limited | Professional & scientific | 2020 |
| Nadesprings Healthcare Ltd | Health & social care | 2023 |
| Nadia Group Ltd | Other services | 2017 |
| Nadjo Biomedicals Limited | Health & social care | 2014 |
| Naek Ltd | Wholesale & retail | 2026 |
| Naga Funding Limited | Financial services | 2017 |
| Nagoja UK Ltd | Construction | 2019 |
| Nagreen Concepts Ltd | Wholesale & retail | 2020 |
| Nails on Nails Ltd | Other services | 2022 |
| Nain Healthcare Ltd | Health & social care | 2023 |
| Nakamya Consultancy Limited | Health & social care | 2012 |
| Nakoasofasan Limited | Health & social care | 2016 |
| Namasthe Saab Ltd | Hospitality | 2024 |
| NAN Trans Limited | Transport & logistics | 2016 |
| Nana Gyarko Healthcare Solutions Limited | Health & social care | 2018 |
| Nanee Foods Ltd | Wholesale & retail | 2025 |
| Nani Construction Ltd | Construction | 2019 |
| Nanninella Ltd | Hospitality | 2018 |
| Nant HIR Farm Services Limited | Professional & scientific | 2005 |
| Narcis VS Limited | Administrative & support | 2017 |
| Nasah Limited | Health & social care | 2011 |
| Nash Electrical Services BA Limited | Manufacturing | 2019 |
| Natasha Brennan Aesthetics Limited | Other services | 2023 |
| Nation Properties Ltd | Construction | 2018 |
| National Fleet Wash & Jetwash Services Ltd | Administrative & support | 2021 |
| Nationwide Contracting Services Ltd | Construction | 2022 |
| Nationwide IT Consultancy Limited | Information & communication | 2010 |
| Nationwide Tower Crane Management Ltd | Construction | 2024 |
| Natrose Properties Ltd | Real estate | 2024 |
| Natshunt Limited | Wholesale & retail | 2025 |
| Natural Pure Organic Ltd | Wholesale & retail | 2018 |
| Naturally Pure and Organic Minerals Limited | Manufacturing | 2026 |
| Nautintel Limited | Other services | 2025 |
| Navale Medical Services Limited | Health & social care | 2023 |
| Navam Coffee Limited | Hospitality | 2023 |
| Navam Properties Limited | Real estate | 2020 |
| Navamcare Limited | Health & social care | 2023 |
| Navs Prosper Ltd | Education | 2022 |
| Nawal Fish and Chips Ltd | Hospitality | 2025 |
| NB3 Projects Limited | Construction | 2026 |
| NB3 Real Estate Limited | Real estate | 2025 |
| NC News Colchester Ltd | Wholesale & retail | 2017 |
| NC04022025 Limited | Professional & scientific | 2013 |