| Montague Clothing Co Ltd | Wholesale & retail | 2024 |
| Montclair Property Ltd | Real estate | 2024 |
| Monte Capital Ltd | Real estate | 2019 |
| Monte Enterprise Ltd | Real estate | 2020 |
| Monte Property Ltd | Real estate | 2019 |
| Monte Wealth Ltd | Financial services | 2019 |
| Montefiore Properties Limited | Real estate | 2021 |
| Montessori & ME Nursery Ltd | Education | 2018 |
| Montessori Minds Ltd | Education | 2017 |
| Monto Events Ltd | Arts & recreation | 2022 |
| Montyclean Limited | Administrative & support | 2025 |
| Monument Brickwork Ltd | Construction | 2020 |
| Monur Ltd | Wholesale & retail | 2023 |
| Monzy's Firm Ltd | Information & communication | 2018 |
| Moonlight Group UK Ltd. | Wholesale & retail | 2019 |
| Moonrise Vintage Ltd | Wholesale & retail | 2025 |
| Moonshine Security UK Ltd | Administrative & support | 2022 |
| Moontales Publishing U.K Limited | Information & communication | 2011 |
| Moore & Moore PI Limited | Real estate | 2025 |
| Moore Foods Limited | Wholesale & retail | 2024 |
| Mooremack Developments Ltd | Construction | 2024 |
| Mooremack Maintenance Ltd | Construction | 2024 |
| Moorhaven Management Limited | Households | 2002 |
| Moorthy & Co. Property Ltd | Financial services | 2025 |
| More Items Store Ltd | Wholesale & retail | 2025 |
| More TEL Ltd | Wholesale & retail | 2019 |
| More.G Ltd | Wholesale & retail | 2022 |
| Moreh Oak Limited | Information & communication | 2020 |
| Morelands Industrial Estate Limited | Real estate | 2018 |
| Morgan & Dixon Properties Limited | Real estate | 2018 |
| Morgan & Dixon Property LLP | | 2012 |
| Morgan Willow Ltd | Real estate | 2026 |
| Morganballards Limited | Professional & scientific | 2013 |
| Morgun Consultants Ltd | Professional & scientific | 2024 |
| Morgun Holdings Ltd | Real estate | 2024 |
| Morgun Sakelis Investments Limited | Construction | 2023 |
| Moriss Limited | Other services | 2023 |
| Morosan Access Ltd | Construction | 2017 |
| Morranti Limited | Information & communication | 2025 |
| Morris Investments Group Limited | Real estate | 2025 |
| Mortubo Consulting Limited | Professional & scientific | 2024 |
| Mory Retail Ltd | Wholesale & retail | 2025 |
| Mosaic Party Walls Ltd | Professional & scientific | 2022 |
| Moscow Consulting Limited | Professional & scientific | 2021 |
| Moscow Investment Limited | Professional & scientific | 2021 |
| Moses Johnson Ltd | Construction | 2014 |
| Mossscent UK Candle Ltd | Wholesale & retail | 2023 |
| Mossscentsuk Ltd | Wholesale & retail | 2023 |
| Motionhq Ltd | Wholesale & retail | 2025 |
| Motiv Advertising Ltd | Administrative & support | 2025 |
| Motivation Chick Limited | Health & social care | 2020 |
| Moto Vehicle Assist Ltd | Wholesale & retail | 2026 |
| Motor Magic Limited | Wholesale & retail | 2015 |
| Motor Magic Tyres & Repairs Ltd | Wholesale & retail | 2021 |
| Motor Maniacs Ltd | Wholesale & retail | 2022 |
| Motormotive Ltd | Wholesale & retail | 2026 |
| Motors for YOU Ltd | Wholesale & retail | 2022 |
| Motorsporttechnik Ltd | Wholesale & retail | 2023 |
| Motorway Boys Enterprise Ltd | Wholesale & retail | 2025 |
| Motovault Solutions Ltd | Transport & logistics | 2024 |
| Mottaz Consultancy Limited | Administrative & support | 2011 |
| Mouchack Ltd | Administrative & support | 2013 |
| Mount House Motors Limited | Wholesale & retail | 2025 |
| Mount Loftus Ltd | Real estate | 2023 |
| Mountain Resin Ltd | Wholesale & retail | 2024 |
| Mountford Developments Ltd | Construction | 2023 |
| Mouse Music Group Ltd | Information & communication | 2024 |
| Movals LLC Ltd | Transport & logistics | 2026 |
| Movement IS Medicine Ltd | Other services | 2024 |
| Moveora Property Group Ltd | Construction | 2026 |
| Moveworks Limited | Administrative & support | 2006 |
| Mowgli's Lead and Lodge Ltd | Other services | 2026 |
| Moyies Ltd | Construction | 2017 |
| MP Beauty and Aesthetics Ltd | Other services | 2026 |
| MP Direct Solutions Ltd | Professional & scientific | 2013 |
| MP Housing & Developments Ltd | Real estate | 2023 |
| MP Landscapes Ltd | Administrative & support | 2023 |
| MP Team Services Ltd | Construction | 2026 |
| MP-K9 Security Ltd | Administrative & support | 2016 |
| Mp-Uk Ltd | Construction | 2017 |
| MPA Electrical Installation Limited | Construction | 2015 |
| MPE Accounting Services Limited | Professional & scientific | 2000 |
| Mpkb Limited | Real estate | 2019 |
| Mpower Site Services Ltd | Construction | 2024 |
| MQ Joinery Ltd | Manufacturing | 2022 |
| Mqplus Ltd | Professional & scientific | 2019 |
| MR and MRS Jadeja Ltd | Health & social care | 2023 |
| MR Beezy Ltd | Education | 2014 |
| MR Betterlife Overseas Ltd | Information & communication | 2024 |
| MR Fashion Merchant Limited | Information & communication | 2025 |
| MR Fast Food Ltd | Hospitality | 2023 |
| MR G Lift Ltd | Construction | 2017 |
| MR GAS Services Limited | Construction | 2020 |
| MR Globals Limited | Wholesale & retail | 2025 |
| MR Jell Limited | Wholesale & retail | 2025 |
| MR London Investments Ltd | Real estate | 2024 |
| MR P'S Corporation Ltd | Wholesale & retail | 2019 |
| MR Project Engineering 2025 Ltd | Professional & scientific | 2025 |
| MR Scanning Freelance Ltd | Health & social care | 2024 |
| MR Simms Olde Sweet Shoppe East Dulwich Limited | Wholesale & retail | 2018 |