| Movie Link Limited | Information & communication | 2019 |
| Mowgli Coffee Oakwood Limited | Hospitality | 2025 |
| Moxy Logistics Ltd | Transport & logistics | 2021 |
| Moysov 87 Ltd | Transport & logistics | 2015 |
| MPG Heating Ltd | Construction | 2010 |
| MQ Tailoring Ltd | Administrative & support | 2026 |
| MR Electric JIS Ltd | Construction | 2025 |
| MR HUG Limited | Real estate | 2023 |
| MR HUG Properties LLP | | 2023 |
| MR Monkey Vape Ltd | Wholesale & retail | 2017 |
| MR Ruislip Car Wash Ltd | Administrative & support | 2023 |
| MR Smart Transport Service Ltd | Transport & logistics | 2025 |
| MRB Interior Design Ltd | Manufacturing | 2025 |
| Mrkt Insights 2020 LLP | | 2019 |
| Mrkt Insights Ltd | Information & communication | 2021 |
| MRS Singh Academy Ltd | Education | 2021 |
| Mshr Capital Ltd | Real estate | 2020 |
| MSI Marine Ltd | Wholesale & retail | 2018 |
| MT Beauty LMT Company Ltd | Other services | 2024 |
| Mtlg Training Solutions Ltd | Education | 2026 |
| Muchenje Limited | Information & communication | 2020 |
| MUD Shareholding Limited | Financial services | 2025 |
| Muddicuts Limited | Other services | 2017 |
| Mudu Consultants Ltd | Information & communication | 2025 |
| Mulburries Ltd | Real estate | 2021 |
| Mulburries Prime Ltd | Real estate | 2024 |
| Muldoon Construction Ltd | Construction | 2026 |
| Mulligan Project Management Ltd | Administrative & support | 2023 |
| Mullins Electrical Services Limited | Construction | 2019 |
| Multicraft Ltd | Construction | 2021 |
| Multiple Links Limited | Administrative & support | 2020 |
| Mummery and Mummery Ltd | Construction | 2019 |
| Mummery and Mummery Renewables Ltd | Construction | 2024 |
| Munch Bite Limited | Wholesale & retail | 2016 |
| Munday Property Limited | Construction | 2022 |
| Murphy Commercial Management Limited | Professional & scientific | 2022 |
| Murray’S Construction Ltd | Construction | 2021 |
| Music and Brands Limited | Extraterritorial | 2017 |
| Music Art Company Angelica Lopez Ltd | Arts & recreation | 2020 |
| Musical Orbit Limited | Education | 2015 |
| Muñequita Products Ltd | Manufacturing | 2019 |
| MVS Logistic Ltd | Transport & logistics | 2019 |
| MXE Constructions Ltd | Construction | 2025 |
| My Consultancy Matters Ltd | Professional & scientific | 2022 |
| My Last Goodbye Limited | Wholesale & retail | 2013 |
| My Olive Branch Ltd | Wholesale & retail | 2011 |
| My Zone(Uk) Ltd | Information & communication | 2019 |
| MY7HEAVENS Ltd | Wholesale & retail | 2018 |
| Mylar Design LDN Limited | Administrative & support | 2021 |
| Mylittle.Craftitude Ltd | Wholesale & retail | 2024 |
| Myteachertraining.Com Ltd | Education | 2020 |
| Mytoor Limited | Professional & scientific | 2017 |
| MZ Joinery and Woodworks Ltd | Other services | 2023 |
| MZE Pictures Ltd | Information & communication | 2022 |
| MZW Engineering Consultants Ltd | Professional & scientific | 2011 |
| Mélo Dental Aesthetics Limited | Health & social care | 2024 |
| N & N Admin Services Ltd | Wholesale & retail | 2013 |
| N D Paving & Building Limited | Construction | 2015 |
| N&A Botanicals Ltd | Manufacturing | 2025 |
| N&J IT Consultancy Limited | Information & communication | 2014 |
| N2S Consulting Limited | Information & communication | 2002 |
| Nader Tech Ltd | Information & communication | 2013 |
| Nadirah & Co Ltd | Other services | 2020 |
| Nagare Capital Limited | Financial services | 2025 |
| Nagpal Food and Wine Limited | Wholesale & retail | 2013 |
| Nagra Sons Limited | Real estate | 2025 |
| NAI Solutions Limited | Information & communication | 2014 |
| Naked Health Group Ltd | Manufacturing | 2018 |
| Naklang Limited | Wholesale & retail | 2026 |
| Namastea Ltd | Hospitality | 2025 |
| Nana Bimpong Ltd | Construction | 2017 |
| Nantong Chengliang Marine Machinery Manufacturing Co., Ltd. | Wholesale & retail | 2024 |
| Nantong Shangcheng Metal Technology Co., Ltd | Wholesale & retail | 2025 |
| Naomi Wallace Asher Limited | Professional & scientific | 2024 |
| NAP Consultancy & Investments Ltd | Real estate | 2019 |
| Narm Investments Ltd | Real estate | 2024 |
| Nastiuc Empire Ltd | Construction | 2021 |
| Natesans Galleries Limited | Wholesale & retail | 1990 |
| Nathan's Nibbles Limited | Hospitality | 2017 |
| Nathans Ice Cream Parlour Ltd | Hospitality | 2022 |
| National Building Operations Limited | Construction | 2024 |
| National BUS Group Ltd | Transport & logistics | 2016 |
| National Homestay UK Ltd | Hospitality | 2018 |
| Native Speaks UK Ltd | Professional & scientific | 2019 |
| Natural Chandler Ltd | Manufacturing | 2020 |
| Naturally Best (Produce) Limited | Hospitality | 2005 |
| Naturally Delightful Ltd | Wholesale & retail | 2026 |
| Nautilus International Ltd | Information & communication | 2019 |
| Nava Medical Ltd | Health & social care | 2020 |
| Navicore Systems Ltd | Information & communication | 2024 |
| Naysha Limited | Construction | 2026 |
| Nazagor Ltd | Transport & logistics | 2021 |
| Ncpc Limited | Wholesale & retail | 1997 |
| NCS Back Office Services Ltd | Construction | 2020 |
| NCU DRY Lining Ltd | Construction | 2019 |
| ND Groundworks Ltd | Construction | 2022 |
| NED Doherty Rentals Limited | Real estate | 2023 |
| NED Group Limited | Wholesale & retail | 2020 |
| Nefermyst Limited | Wholesale & retail | 2025 |
| Nelivia Ltd | Health & social care | 2021 |