| Moorgate Mortgages Ltd | Financial services | 2022 |
| Moose Building Solutions Ltd | Construction | 2009 |
| Moov Parnters Ltd | Administrative & support | 2025 |
| Morbel Construction Ltd | Construction | 2025 |
| More Business HQ Ltd | Information & communication | 2019 |
| More Life Property Ltd | Real estate | 2019 |
| Morgan Neighbour Coaching Ltd | Education | 2026 |
| Morgarten Holdings Limited | Administrative & support | 2018 |
| Mori Tatt Ltd | Hospitality | 2026 |
| Morning DEW Development Limited | Construction | 2023 |
| Morning Glory Topco Ltd | Professional & scientific | 2024 |
| Morris & Sons Investment Limited | Hospitality | 2019 |
| Morrison Contracts Limited | Manufacturing | 2014 |
| Morrisons Properties Limited | Real estate | 2020 |
| Morrisons Property Management Limited | Real estate | 2020 |
| Morton Mulberry Silk Ltd | Wholesale & retail | 2020 |
| Moscow Connect Ltd | Professional & scientific | 2024 |
| Moss Waking Watch Services Ltd | Administrative & support | 2024 |
| Mosspig Limited | Manufacturing | 2024 |
| Mother Ginger Ltd | Other services | 2024 |
| Motion Recruitment Ltd | Administrative & support | 2022 |
| Motion Ventures Ltd | Hospitality | 2019 |
| Motiv Music UK Limited | Information & communication | 2021 |
| Motivated Learning LLP | | 2026 |
| Motor ED Transports Ltd | Transport & logistics | 2017 |
| Motoract Motors Limited | Wholesale & retail | 2020 |
| Moulton Johnson Limited | Professional & scientific | 2010 |
| Mount Thrift Management Ltd | Real estate | 2024 |
| Mount Thrift Occupational Health Limited | Administrative & support | 2014 |
| Mountnessing Fields Limited | Households | 2010 |
| Mountnessing Partners Ltd | Administrative & support | 2019 |
| Mountune 2 Limited | Other services | 2020 |
| Mountune Racing 2 Limited | Other services | 2020 |
| Move for Life Ltd | Other services | 2011 |
| Move-A-Safe Limited | Manufacturing | 2002 |
| Movezen Group Ltd | Transport & logistics | 2023 |
| Movitation Limited | Other services | 2019 |
| Moxie Pictures LLP | | 2005 |
| MP Heating and Plumbing Ltd | Construction | 2018 |
| MR Big Recovery Ltd | Wholesale & retail | 2011 |
| MR Creative Limited | Professional & scientific | 2017 |
| MR Elegance Essex Ltd | Other services | 2026 |
| MR FFF Coaching LLP | | 2026 |
| MR Golf Academy Ltd | Wholesale & retail | 2022 |
| MR Green & Smart Transport Solutions Ltd | Manufacturing | 2021 |
| MR Makeup BOY Ltd | Wholesale & retail | 2025 |
| MR Pike the Movie Limited | Information & communication | 2018 |
| MR Reason and MR Squalor Ltd | Arts & recreation | 2009 |
| MRG Private Clients Ltd | Financial services | 2011 |
| Mroc Building Services Ltd | Professional & scientific | 2016 |
| Mrpm Services Limited | Professional & scientific | 2009 |
| MRSC20 Limited | Real estate | 2020 |
| MRT Repairs Centre Ltd | Information & communication | 2017 |
| MRT Risk Consultancy Ltd | Professional & scientific | 2015 |
| MS CRM Experts Limited | Information & communication | 2012 |
| MS Safety in Design Ltd | Professional & scientific | 2018 |
| MSA Cars Ltd | Wholesale & retail | 2018 |
| Mscloudgenie Ltd | Information & communication | 2019 |
| Msms Property Investments Ltd | Real estate | 2026 |
| Msms Supermarket Limited | Wholesale & retail | 2014 |
| Msms Superstore Limited | Wholesale & retail | 2014 |
| MSR Umbrella Services Ltd | Administrative & support | 2016 |
| Mstp Limited | Real estate | 2024 |
| Mstr Medical Beauty Ltd | Other services | 2025 |
| Msul Solutions Ltd | Professional & scientific | 2019 |
| MSV Entertainment Ltd | Administrative & support | 2021 |
| MT Creative Management Ltd | Arts & recreation | 2017 |
| MT Educate Ltd | Education | 2023 |
| MT2 Electrical Contractors Ltd | Construction | 2023 |
| Mtimis Limited | Wholesale & retail | 2024 |
| Mtsb Consulting Ltd | Administrative & support | 2022 |
| MTY Bespoke Ltd | Manufacturing | 2025 |
| Muja Wires Ltd | Construction | 2022 |
| Mulberry Enterprises Limited | Wholesale & retail | 2006 |
| Mulberry Green Management Company Limited | Households | 2020 |
| Mulder GAS & Heating Limited | Other services | 2015 |
| Multibeton Ltd. | Construction | 1976 |
| Multify Ltd | Construction | 2025 |
| Multitalent Training Services Ltd | Administrative & support | 2011 |
| Multitech Maintenance Limited | Construction | 2006 |
| Multiview Limited | Administrative & support | 2004 |
| Mumafe LLP | | 2026 |
| Munaf ALI Consultancy Limited | Professional & scientific | 2003 |
| Munns Place Ltd | Professional & scientific | 2012 |
| Muns Interiors Ltd | Other services | 2020 |
| Muntjac Furniture Limited | Manufacturing | 2024 |
| Murco (Electrical) Limited | Other services | 1961 |
| Musca D Transport Ltd | Administrative & support | 2014 |
| Musgrave Financial Limited | Professional & scientific | 2017 |
| Muslimah Life Coach Ltd | Health & social care | 2025 |
| Mutual Driving School Limited | Other services | 2018 |
| MVG Electrical Ltd | Construction | 2018 |
| MWH Programme Services Limited | Information & communication | 2025 |
| My Brentwood Barbers Ltd | Other services | 2025 |
| My Buggy Buddy Ltd. | Wholesale & retail | 2010 |
| My Constellation Limited | Administrative & support | 2023 |
| My Fight Camp Nutrition Ltd | Arts & recreation | 2025 |
| My Little Find Ltd | Wholesale & retail | 2026 |
| My Path 2 Wellness CIC | Health & social care | 2023 |
| My Time to Reign Ltd | Professional & scientific | 2020 |