| MSG Dental Care Limited | Health & social care | 2021 |
| MSG Elite Cleaning Services Ltd | Administrative & support | 2026 |
| MSJ Fittings Limited | Wholesale & retail | 2025 |
| Msko Investments Ltd | Real estate | 2021 |
| MSL Projects Limited | Construction | 1993 |
| MSM Land Ltd | Real estate | 2024 |
| MSV Building Contractors Ltd | Construction | 2025 |
| Mtech Auto Group Ltd | Wholesale & retail | 2019 |
| Mtech Autoworx Ltd | Wholesale & retail | 2026 |
| Mtliedke Ltd | Transport & logistics | 2018 |
| Mtweedy Limited | Professional & scientific | 2026 |
| Mudd Waste Solutions Ltd | Water & waste | 2020 |
| Muddy Paws Darlington Ltd | Professional & scientific | 2025 |
| Mujan Limited | Wholesale & retail | 2018 |
| Mulberry Park Sporting Ltd | Arts & recreation | 2024 |
| Mulholland Builders Limited | Construction | 2020 |
| Multani (BS) Ltd | Wholesale & retail | 2025 |
| Mummyjobs.Co.Uk Ltd | Administrative & support | 2017 |
| Munchie Van Ltd | Hospitality | 2024 |
| Murdoch Project Controls Ltd | Professional & scientific | 2022 |
| Murray and SON Rooflines Limited | Construction | 2022 |
| Murray Klet Limited | Real estate | 2024 |
| Murray Properties Group Ltd | Real estate | 2025 |
| Murray's Project Services Ltd | Mining & quarrying | 2011 |
| Musa Fast Food Ltd | Hospitality | 2024 |
| Muse Restaurants Ltd | Hospitality | 2014 |
| Mussel Technologies Limited | Information & communication | 2021 |
| Mutlu Turkish Barbers Limited | Other services | 2019 |
| MV Tuning Solutions Limited | Wholesale & retail | 2020 |
| MW Rail Limited | Construction | 2026 |
| MWB Services Ltd | Construction | 2022 |
| MWO Services Ltd | Professional & scientific | 2018 |
| MWP Frames Ltd | Construction | 2013 |
| Mwra Ltd | Construction | 2021 |
| My Companion Ltd | Health & social care | 2024 |
| My DAD BAZ Limited | Extraterritorial | 2011 |
| My Driving Licence Driving School Limited | Education | 2019 |
| My Gleeful Box Limited | Wholesale & retail | 2020 |
| My Health Matters Healthcare Limited | Health & social care | 2025 |
| My Home Trend Ltd | Professional & scientific | 2019 |
| My Key Properties Ltd | Real estate | 2019 |
| My Marketing Button Limited | Professional & scientific | 2017 |
| My Property Box Holdings Limited | Financial services | 2024 |
| My Property Box Ltd | Real estate | 2012 |
| My Property PAL Ltd | Professional & scientific | 2023 |
| MYK Baxter Marketing Limited | Professional & scientific | 2021 |
| N & N Trading Limited | Wholesale & retail | 2020 |
| N Clark Consulting Services Ltd | Education | 2017 |
| N G Pipe Fitting Limited | Construction | 2018 |
| N J Cooper Joinery & Building Contractors Ltd | Construction | 2010 |
| N W NE Limited | Wholesale & retail | 2026 |
| N Welch Properties Ltd | Real estate | 2022 |
| N&K Aldus Group Ltd | Professional & scientific | 2026 |
| N&S PUB Company Limited | Hospitality | 2022 |
| N.E Transport Limited | Transport & logistics | 2022 |
| N.E. Auto Tech Holdings Ltd | Wholesale & retail | 2025 |
| N.U.Majesty Ltd | Other services | 2018 |
| Naijahub UK Ltd | Information & communication | 2025 |
| Nails by Katie COX Ltd | Other services | 2025 |
| Naisbitt Limited | Wholesale & retail | 2025 |
| Naked Restaurant Group Ltd | Hospitality | 2019 |
| Naltsad | Extraterritorial | 2016 |
| Namais Ltd | Professional & scientific | 2023 |
| Nano Design Services Ltd | Professional & scientific | 2024 |
| Nano Electronic Services Ltd | Professional & scientific | 2020 |
| Naples Components Limited | Wholesale & retail | 1997 |
| Nasr & El-Okbey Legal Consultancy & Company Formation Ltd | Extraterritorial | 2025 |
| Natalie Lowes Ltd | Other services | 2018 |
| National Commercial Bodies Limited | Manufacturing | 2024 |
| National Council of Women of Great Britain(The) | Education | 1951 |
| National Utility Network Limited | Wholesale & retail | 2016 |
| Nationwide First AID Training Limited | Education | 2024 |
| Nationwide Vehicle Recoveries Ltd | Wholesale & retail | 2018 |
| Natkay Ltd | Professional & scientific | 2014 |
| Natural Synergies Limited | Water & waste | 2012 |
| Nature Based Solutions Limited | Administrative & support | 2020 |
| Nature's Mojo Ltd | Manufacturing | 2021 |
| Natureas Limited | Wholesale & retail | 2011 |
| Navision Ltd | Health & social care | 2023 |
| NB OM Subco Limited | Health & social care | 2026 |
| NBG 2027 Ltd | Wholesale & retail | 2026 |
| Nbti Limited | Wholesale & retail | 2025 |
| Nbtyres - UK Wholesale Ltd | Wholesale & retail | 2026 |
| NC Axiom Ltd | Information & communication | 2026 |
| Ncass Limited | Administrative & support | 2026 |
| NCB Hazcheck Limited | Information & communication | 1986 |
| NCH Entertainment Ltd | Arts & recreation | 2019 |
| ND118 Ltd | Hospitality | 2019 |
| NDL Ltd | Professional & scientific | 2022 |
| NDS Developments NE Limited | Construction | 2025 |
| NE Design and Engineering Limited | Professional & scientific | 2019 |
| NE Maintenance Services Limited | Administrative & support | 2019 |
| NE Tackle Ltd | Wholesale & retail | 2022 |
| NE1 Plumbers Ltd | Construction | 2025 |
| Neasham Estate Limited | Real estate | 1936 |
| Neasham Nurseries Ltd | Agriculture & fishing | 2008 |
| Neasham Solutions Ltd | Construction | 2025 |
| NEASHAM153 Limited | Hospitality | 2020 |
| Neaves Bakes Ltd | Wholesale & retail | 2026 |
| Neil Armstrong and Co Accountancy Services Limited | Professional & scientific | 2015 |