| Mcgarry Geoconsulting Ltd | Professional & scientific | 2022 |
| Mcgowan & Bros Ltd | Construction | 2020 |
| MDM Accounting Limited | Professional & scientific | 2003 |
| Mdp-Computing Ltd | Wholesale & retail | 2025 |
| MEA Consultants Ltd | Other services | 2014 |
| Mebes Motors Ltd | Financial services | 2017 |
| Mega Mart PVT Ltd | Wholesale & retail | 2021 |
| Melanie Clark Limited | Professional & scientific | 2013 |
| Meld Ltd | Manufacturing | 2017 |
| Memflight Ltd | Wholesale & retail | 2018 |
| Men's Policy Project CIC | Education | 2026 |
| Mentors Web Design Ltd | Information & communication | 2025 |
| Merlyn Homes Limited | Construction | 2018 |
| Merrow Mapping Ltd | Professional & scientific | 2024 |
| Mervis Ltd | Health & social care | 2020 |
| Metaproductions Limited | Professional & scientific | 2022 |
| Metis Tech Limited | Administrative & support | 2024 |
| Metro Stop Mobiles Limited | Wholesale & retail | 2021 |
| MIA Special Care Ltd | Hospitality | 2020 |
| MIA Special Ltd | Hospitality | 2018 |
| Miah Indian Takeaway Ltd | Hospitality | 2021 |
| Midicy Management Ltd | Households | 2021 |
| MII Limited | Manufacturing | 2020 |
| Mikafy Ltd | Information & communication | 2026 |
| Milk and Hustle Ltd | Hospitality | 2020 |
| Millgrove Estates Limited | Real estate | 2004 |
| Mini Moons (Sussex) Limited | Health & social care | 2026 |
| Miramus Limited | Arts & recreation | 2009 |
| Missing Link Productions Limited | Education | 2000 |
| MJ Organisational and Management Consultancy Limited | Health & social care | 2022 |
| MJ Sherwood Holding Limited | Financial services | 2025 |
| MJC Capital Ltd | Professional & scientific | 2022 |
| Mmlg Limited | Construction | 1997 |
| MMR Trades Limited | Wholesale & retail | 2025 |
| Mnamky Ltd | Professional & scientific | 2024 |
| Modura Interiors Ltd | Construction | 2025 |
| Mojo Vets Ltd | Professional & scientific | 2024 |
| Molyneux Court Limited | Professional & scientific | 1999 |
| Mongrel Ltd | Manufacturing | 2021 |
| Mono Antiques Limited | Wholesale & retail | 2024 |
| Moorgate Surgeries Ltd | Health & social care | 2015 |
| Moringa Trading Investments Co. Limited | Construction | 1982 |
| Mossgrove Limited | Real estate | 1990 |
| Mosswall UK Ltd | Extraterritorial | 2015 |
| Moth Shop Ltd | Wholesale & retail | 2022 |
| Mother Gorilla Ltd | Professional & scientific | 2024 |
| Movafagh Development Ltd | Real estate | 2025 |
| Move on PAM Ltd | Health & social care | 2014 |
| Move: North Ltd | Arts & recreation | 2025 |
| Movekind CIC | Health & social care | 2026 |
| MPS Private Limited | Professional & scientific | 2023 |
| MRO Limited | Other services | 2020 |
| Mtssd Ltd | Real estate | 2025 |
| MU Mwah Ltd | Hospitality | 2020 |
| Murano House Management Co Ltd | Real estate | 2011 |
| Murphys Rail & Construction Limited | Construction | 2019 |
| Muse Corporation Limited | Information & communication | 2018 |
| My GAS Boiler Limited | Construction | 2017 |
| My Tiny Town Ltd | Arts & recreation | 2023 |
| Mystic Rose Ltd | Administrative & support | 2019 |
| N60 Limited | Administrative & support | 2012 |
| Namoz Limited | Hospitality | 2024 |
| Nanotech Consulting Ltd. | Professional & scientific | 2013 |
| National Secure Ambulance Alliance Limited | Other services | 2026 |
| Naturebytes C.I.C. | Education | 2014 |
| Navsan Enterprises UK Ltd | Wholesale & retail | 2025 |
| Naylor Rail Limited | Professional & scientific | 2016 |
| NCK Research Ltd | Professional & scientific | 2020 |
| Neale Willis Limited | Arts & recreation | 2007 |
| Neat-Lycom Ltd | Administrative & support | 2025 |
| Neovo Ltd | Construction | 2025 |
| Nevill Court Hove Limited | Households | 2017 |
| New Building Materials Limited | Wholesale & retail | 2023 |
| New Maisonettes Management Company Limited | Professional & scientific | 2005 |
| New Spice Ltd | Hospitality | 2019 |
| Newmans DRY Cleaners Ltd | Other services | 2022 |
| Nexora Global Affairs Ltd | Information & communication | 2025 |
| Nexphase Electrical Ltd | Construction | 2025 |
| Next Generation Networks Limited | Information & communication | 2024 |
| NEXTGEN1066 Ltd | Construction | 2025 |
| Nick Ballon Photography Limited | Professional & scientific | 2014 |
| Niffy Rocks Limited | Information & communication | 2003 |
| Nigerian- British Chamber UK Ltd | Administrative & support | 2026 |
| Ninety Nine Surveying (Sussex) Ltd | Professional & scientific | 2024 |
| Ninety Nine Surveying Limited | Professional & scientific | 2017 |
| NO Fast NO Furiouz Ltd | Information & communication | 2025 |
| NO Other Purpose Limited | Arts & recreation | 2023 |
| NO Pictures Ltd | Information & communication | 2023 |
| NO. 57 the Drive Hove, Limited | Households | 1965 |
| Noble Care Homes Ltd | Health & social care | 2022 |
| Norcross Meridian Ltd | Wholesale & retail | 2026 |
| Northumberland Court Management (Brighton) Limited | Households | 1979 |
| Novatech Loadcells D & M Limited | Manufacturing | 2021 |
| NPW Group Ltd | Construction | 2025 |
| NUR Supermarket Limited | Wholesale & retail | 2024 |
| Nursebank Limited | Administrative & support | 2015 |
| Nutritiongetsnude Limited | Information & communication | 2003 |
| Nuts About Cookies Ltd | Manufacturing | 2017 |
| Oak & Stable Ltd | Manufacturing | 2026 |
| Oakfield Investment Assets Limited | Financial services | 2024 |