| MKW Access Scaffolding Ltd | Construction | 2022 |
| MM Global Invest Limited | Extraterritorial | 2014 |
| Mobility Services International UK LLC | | 2008 |
| Modern Electrical Services Ltd | Construction | 2010 |
| Modus Sports Management Limited | Professional & scientific | 2008 |
| Moisal Ascot Ltd | Hospitality | 2010 |
| Mojaberry Limited | Administrative & support | 2015 |
| Momentum Global Network Limited | Information & communication | 2012 |
| Momentum Marketing Team Limited | Professional & scientific | 2017 |
| Monafs Indian Cuisine Limited | Hospitality | 2026 |
| Monday Property Ltd | Real estate | 2018 |
| Monetae Bullion Limited | Wholesale & retail | 2015 |
| Monkey Bean Media Limited | Information & communication | 2014 |
| Monkey Properties Ltd | Real estate | 2025 |
| Monkey Ventures Ltd | Real estate | 2025 |
| Monotrade Limited | Wholesale & retail | 2008 |
| Mont Pearl Limited | Wholesale & retail | 2012 |
| Monte Alto Solutions Limited | Professional & scientific | 2017 |
| Monte Cristo Properties Ltd | Extraterritorial | 2016 |
| Mood Indigo Events Limited | Arts & recreation | 2016 |
| Moonbeam Marketing & Consulting Ltd | Professional & scientific | 2025 |
| Morgan Finch & Partners Limited | Professional & scientific | 1980 |
| Morgan Stewart Interiors Ltd | Administrative & support | 2014 |
| Moto BIO Ltd | Information & communication | 2022 |
| Moto Inspection Ltd | Wholesale & retail | 2024 |
| Motorwise ( Mot`S) Limited | Wholesale & retail | 2010 |
| Movess Realty Ltd | Extraterritorial | 2017 |
| MR. Gain Ltd | Wholesale & retail | 2021 |
| Mukwano Gw'Abato Limited | Education | 2019 |
| Multiservicesvs Ltd | Other services | 2018 |
| Munchies @ 3RD Hampton Limited | Health & social care | 2016 |
| Muniment Bradford Developments Ltd | Real estate | 2014 |
| Muniment Greenwich Ltd | Real estate | 2014 |
| Muniment Limited | Real estate | 2013 |
| Muniment Property Developments Ltd | Construction | 2018 |
| Muniment Warrington Ltd | Real estate | 2014 |
| Munro&Co Ltd | Wholesale & retail | 2020 |
| Murphy & Liang Ltd | Health & social care | 2025 |
| Music Over Everything CIC | Administrative & support | 2024 |
| MW Event Services Ltd | Administrative & support | 2026 |
| My Good Wardrobe Ltd | Wholesale & retail | 2023 |
| My Huise Ltd | Real estate | 2017 |
| My Iwear Ltd | Wholesale & retail | 2011 |
| My Supermart Ltd | Wholesale & retail | 2019 |
| Mzima Investments Ltd | Real estate | 2019 |
| N Chopra Ltd | Wholesale & retail | 2025 |
| Nadia Cicele Design Ltd | Professional & scientific | 2020 |
| Nails & More Ltd | Other services | 2026 |
| Nano Investments Ltd | Real estate | 2014 |
| Napier Court (Lovelace Gardens) Residents Association Limited | Households | 1973 |
| Narin Thai Therapy Ltd | Other services | 2026 |
| Nathans Accountants Limited | Extraterritorial | 2013 |
| National Testing Services Limited | Professional & scientific | 2015 |
| Naunoor Limited | Wholesale & retail | 2021 |
| Navigare Ventures Limited | Information & communication | 2026 |
| NB Coin Ltd | Other services | 2023 |
| NBR Property Limited | Real estate | 2023 |
| Nearart (Building) Limited | Construction | 1989 |
| Neil Lucas Building & Landscapes Ltd | Construction | 2019 |
| Nelisiwe Limited | Health & social care | 2012 |
| Nellies London Ltd | Manufacturing | 2018 |
| Nest Habitat Ltd | Real estate | 2018 |
| Network Delivery Consultancy Limited | Information & communication | 2021 |
| Neudwell PTE Ltd | Extraterritorial | 2019 |
| Neuroyogaplus Ltd | Wholesale & retail | 2025 |
| New Media Networks Limited | Professional & scientific | 2008 |
| New Tides Productions Limited | Information & communication | 2012 |
| New Ventures Holdings Ltd | Real estate | 2016 |
| Newline Security Solutions Ltd | Administrative & support | 2025 |
| NEX GEN Build Ltd | Construction | 2025 |
| Nexa Resourcing Ltd | Administrative & support | 2026 |
| Next Tuesday Limited | Information & communication | 2017 |
| Nextgen Roofing Specialist Ltd | Construction | 2025 |
| Nexus IP Limited | Information & communication | 2018 |
| Ngage Therapy Ltd | Health & social care | 2020 |
| Ngin and Sons Limited | Real estate | 2017 |
| Nickel Aviation Ltd | Professional & scientific | 2021 |
| Nicolett Alexandra Art Ltd | Arts & recreation | 2013 |
| Night Smart Automotive Ltd | Financial services | 2022 |
| Nimbus Realty Ltd | Real estate | 2019 |
| Ninanaira Ltd | Other services | 2024 |
| Nineagle Ltd | Professional & scientific | 2015 |
| Nineteen Adelaide Road Limited | Households | 1961 |
| Nivellaink Ltd | Wholesale & retail | 2026 |
| NJS Accounting Ltd | Professional & scientific | 2025 |
| NNG Services Ltd | Administrative & support | 2022 |
| NO. 74 Clinics Ltd | Health & social care | 2021 |
| Noise Supply Ltd | Professional & scientific | 2005 |
| North London Autocare Limited | Wholesale & retail | 2021 |
| Northumberland Place Management Co. Limited | Households | 1983 |
| Nova Aviation Ltd | Professional & scientific | 2024 |
| Novum Horizon Ltd | Real estate | 2017 |
| NOW Book IT Ltd | Information & communication | 2016 |
| NOW I Work Ltd | Other services | 2003 |
| NR Coaching Ltd | Arts & recreation | 2021 |
| Nrcc LLP | | 2018 |
| NSS Incorporation Ltd | Extraterritorial | 2018 |
| Number One John Street Limited | Households | 1996 |
| Nurapace Ltd | Information & communication | 2026 |
| Nursery Gardens Management Limited | Real estate | 2000 |