| Monadia Ltd | Transport & logistics | 2010 |
| Monah Estates Ltd | Real estate | 2024 |
| Monkey-Trans Ltd | Transport & logistics | 2021 |
| Monolace Limited | Health & social care | 1985 |
| Monopol Northampton Ltd | Wholesale & retail | 2016 |
| Montgomery FS Ltd | Financial services | 2019 |
| Moochi Designs Limited | Manufacturing | 2023 |
| Mooke Home Ltd | Wholesale & retail | 2021 |
| Moor Road Garage Ltd | Wholesale & retail | 2014 |
| Moreks Ltd | Transport & logistics | 2022 |
| Moreworth Ltd | Professional & scientific | 2015 |
| Moreworth Properties Ltd | Real estate | 2022 |
| Morey Electrical Services Ltd | Other services | 2022 |
| Morley Muller Estates Ltd | Real estate | 2021 |
| Morningstar Group Ltd | Manufacturing | 2024 |
| Morrison Automation & Controls Ltd | Professional & scientific | 2019 |
| Moses Foods Ltd | Hospitality | 2025 |
| Mossman Tebbs Handling Ltd | Extraterritorial | 2013 |
| Mossman Tebbs Ltd | Wholesale & retail | 2011 |
| Mosulica Ltd | Manufacturing | 2025 |
| Moth Killers Ltd | Administrative & support | 2019 |
| Moth Trap Ltd | Wholesale & retail | 2024 |
| MOTIV8 Group Ltd | Information & communication | 2013 |
| Motor Technical Services Limited | Manufacturing | 2016 |
| Movcar Logistics Ltd | Transport & logistics | 2022 |
| Move Forwards.Be Useful Limited | Financial services | 2023 |
| Mowerman Maintenance Ltd | Manufacturing | 2022 |
| Mowgli Properties Ltd | Real estate | 2017 |
| MP Nails & Beauty Limited | Other services | 2020 |
| MPC Maxy Ltd | Transport & logistics | 2023 |
| MPG Healthcare Limited | Wholesale & retail | 2015 |
| Mpower Talent Ltd | Administrative & support | 2024 |
| Mprg Limited | Real estate | 2017 |
| MPW Decorating Ltd | Construction | 2017 |
| MR Finder Ltd | Wholesale & retail | 2020 |
| MR Protech Ltd | Wholesale & retail | 2023 |
| Mr.Jay Ltd | Transport & logistics | 2017 |
| MRB Management Ltd | Professional & scientific | 2010 |
| Mreh AL Kindy Property Ltd | Real estate | 2024 |
| MRM Trading & Solutions Ltd | Wholesale & retail | 2024 |
| MRV London Ltd | Wholesale & retail | 2026 |
| MS Trans Services Ltd | Transport & logistics | 2015 |
| Msfb Ltd | Construction | 2014 |
| MSK Autorepairs Ltd | Wholesale & retail | 2022 |
| MSK Prime Ltd | Health & social care | 2025 |
| Msys UK Ltd | Information & communication | 2000 |
| Mtec Installations Ltd | Construction | 2021 |
| Mtechz Ltd | Information & communication | 2025 |
| MTM Parkin Properties Limited | Real estate | 2023 |
| MTR Audio Ltd | Extraterritorial | 2026 |
| Mtungwa Enterprises Limited | Health & social care | 2020 |
| MTV Transport Ltd | Transport & logistics | 2024 |
| Muchem Logistics Limited | Transport & logistics | 2026 |
| Mudav Health Ltd | Health & social care | 2025 |
| Muddy Matches Limited | Information & communication | 2006 |
| Mughal Raunds Ltd | Hospitality | 2019 |
| Mullen & Sons Ltd | Transport & logistics | 2026 |
| Multi-Platform Solutions Limited | Information & communication | 2015 |
| Mundo Express Ltd | Wholesale & retail | 2020 |
| Muppala Ltd | Construction | 2026 |
| Murdoch Norton Limited | Wholesale & retail | 1955 |
| Muwan Ltd | Other services | 2025 |
| MW and TW LLP | | 2011 |
| MW Joiting Ltd | Construction | 2024 |
| Mwendauya Properties Limited | Real estate | 2025 |
| My Ancient World Learning Ltd | Education | 2022 |
| My Happy Play Cafe Ltd | Arts & recreation | 2024 |
| My Healthy Pet Ltd | Wholesale & retail | 2024 |
| My Nurtura Limited | Wholesale & retail | 2025 |
| My Place Property Ltd | Administrative & support | 2023 |
| My Property Stays Limited | Real estate | 2025 |
| My Rental Property Ltd | Real estate | 2018 |
| My Studio Suite Ltd | Information & communication | 2026 |
| Myescape NH Ltd | Arts & recreation | 2018 |
| MYK Mobile Tech Ltd | Wholesale & retail | 2020 |
| Myriad Fabrication Limited | Construction | 2022 |
| MZ Projects Ltd | Professional & scientific | 2020 |
| Mzima Springs Ltd | Real estate | 2023 |
| N M Heating & Cooling Ltd | Administrative & support | 2024 |
| N S J Enterprises Limited | Construction | 2019 |
| N.D.E. Insurance Services Limited | | 1981 |
| N90 Ltd | Extraterritorial | 2015 |
| Naaddo Ltd | Wholesale & retail | 2021 |
| Nafiko Ventures Ltd | Wholesale & retail | 2017 |
| Nail Pro Group Ltd | Other services | 2026 |
| Naji Healthcare Ltd | Health & social care | 2017 |
| Nakov Limited Limited | Wholesale & retail | 2025 |
| Naly Trans Ltd | Manufacturing | 2017 |
| NAMO1 Ltd | Wholesale & retail | 2025 |
| Nannymamie Limited | Health & social care | 2025 |
| Nanu Administration Limited | Administrative & support | 2022 |
| Napleton Developments Limited | Construction | 2019 |
| Napleton Limited | Professional & scientific | 2026 |
| Napleton Wind Power Limited | Energy | 2022 |
| Napsbury Properties Limited | Real estate | 2012 |
| Narrative Audio Ltd | Information & communication | 2017 |
| Nasta Transport Limited | Transport & logistics | 2019 |
| Natchi Health Ltd | Health & social care | 2020 |
| Nathar Ltd | Wholesale & retail | 2011 |
| National Executive Transport Limited | Extraterritorial | 2025 |