| Modha Assets Limited | Financial services | 2023 |
| Modha Pharma Limited | Wholesale & retail | 2024 |
| Modha Residential Ltd | Households | 2023 |
| Mogano Ltd | Construction | 2014 |
| MOH Capital Ltd | Real estate | 2019 |
| MOH Services Ltd | Professional & scientific | 2019 |
| Mohgi Ltd | Information & communication | 2024 |
| Moirai Finance Consultancy Ltd | Professional & scientific | 2025 |
| MOJ Holdings Ltd | Financial services | 2026 |
| Mojho Limited | Professional & scientific | 2024 |
| Mojo Marine Ltd | Extraterritorial | 2025 |
| Mojoco Limited | Administrative & support | 2020 |
| Mojomental LLP | | 2019 |
| Molen Style London Ltd | Manufacturing | 2015 |
| Molten Finance Ltd | Professional & scientific | 2019 |
| Molvic Court RTM Company Ltd | Real estate | 2014 |
| Momikmich Company Ltd | Health & social care | 2014 |
| Mompa Ltd | Manufacturing | 2025 |
| Monarch Marquees Ltd | Administrative & support | 2023 |
| Monarchy Equestrian Limited | Wholesale & retail | 2022 |
| Monday to Friday Tea Ltd | Wholesale & retail | 2017 |
| Monetic Capital Limited | Financial services | 2020 |
| Monioro Services Limited | Administrative & support | 2018 |
| Monkhouse Surgical Limited | Health & social care | 2014 |
| Monochrome Interactive Limited | Information & communication | 2004 |
| Monochrome Limited | Information & communication | 1999 |
| Monro and Bùrn Ltd | Manufacturing | 2017 |
| Monseigneurdj Ltd | Information & communication | 2024 |
| Monsieur Dahlstrom Ltd | Information & communication | 2011 |
| Monster Time Productions Limited | Professional & scientific | 1998 |
| Monteiro Consultancy Ltd | Information & communication | 2013 |
| Monterey Insight Limited | Information & communication | 2012 |
| Montpelier Solicitors Limited | Professional & scientific | 2017 |
| Moolayil Healthcare Limited | Health & social care | 2022 |
| Moonjolly LAB Co. Limited | Extraterritorial | 2018 |
| Moonlite Home Ltd | Real estate | 2019 |
| Moorcroft (Weybridge) Management Company Limited | Households | 2000 |
| Moore House Freehold Company Limited | Households | 2019 |
| Moore Properties II Ltd | Real estate | 2020 |
| Moorham Limited | Construction | 2020 |
| Moorlands (Chislehurst Flats) Limited | Real estate | 1967 |
| Moran Roofing & Building Ltd | Construction | 2019 |
| Moreland Builders and Developers Limited | Construction | 1986 |
| Morello Quarter RTM Co Ltd | Households | 2024 |
| Moresso Ltd | Manufacturing | 2021 |
| Moreton (Sidcup) Management Company Limited | Households | 1982 |
| Morgan Roberts Electrical Limited | Construction | 2015 |
| Morgans Scaffolding Ltd | Construction | 2014 |
| Morley Court (Westmoreland Road) Ltd | Households | 2004 |
| Morley Osteo Aesthetics Ltd | Other services | 2025 |
| Morley Osteopathy Limited | Health & social care | 2022 |
| Morley UK Bidco Limited | Financial services | 2024 |
| Morley UK Holdco Limited | Financial services | 2024 |
| Morning Exchange Ltd | Financial services | 2023 |
| Moro Construct Ltd | Construction | 2023 |
| Mortgage Info Limited | Financial services | 2022 |
| Mortgagetrackai Ltd | Information & communication | 2025 |
| Mortimer Development Group Limited | Construction | 2024 |
| Mosaic Health Ltd | Health & social care | 2020 |
| Mosaic House Ltd | Real estate | 2019 |
| Moshog Ltd | Professional & scientific | 2017 |
| Moss Homes (UK) Limited | Construction | 2014 |
| Mosslea MOT Limited | Wholesale & retail | 2005 |
| Most Trade Team Ltd | Manufacturing | 2023 |
| Motion Captured Limited | Professional & scientific | 2012 |
| Motus Health and Wellbeing Ltd | Health & social care | 2025 |
| Mountain Skyline Ltd | Real estate | 2025 |
| Mounthurst Limited | Professional & scientific | 2018 |
| Mountlake Property Limited | Real estate | 2020 |
| Movement Intellect Ltd | Health & social care | 2017 |
| Movezone Limited | Real estate | 2025 |
| Movezone Property Limited | Real estate | 2025 |
| MP Facilities Management Ltd | Administrative & support | 2022 |
| MPA Development Limited | Professional & scientific | 2002 |
| MPH Design Consultants Ltd | Professional & scientific | 2015 |
| Mpkc Ltd | Wholesale & retail | 2026 |
| Mplr Services Limited | Education | 2024 |
| MPM Strategies LLP | | 2011 |
| Mpower Supported Living Ltd | Health & social care | 2020 |
| MPP Bromley Ltd | Hospitality | 2026 |
| MR & MRS Domestic Cleaning Ltd | Administrative & support | 2026 |
| MR & MRS Peate Limited | Professional & scientific | 2016 |
| MR Bentley Ltd | Wholesale & retail | 2018 |
| MR Favourite Kebab & Grill Ltd | Hospitality | 2021 |
| MR LYE Ltd | Arts & recreation | 2019 |
| Mridley Ltd | Information & communication | 2012 |
| MRM Electrical Contractors Limited | Construction | 2018 |
| MRO People Ltd | Education | 2015 |
| MS Community Housing Ltd | Real estate | 2021 |
| MS Flowers Ltd | Wholesale & retail | 2023 |
| MSC Contracts Limited | Construction | 2016 |
| MSC Coote Ltd | Arts & recreation | 2014 |
| MSE Residential Properties Ltd | Real estate | 2023 |
| MSL Couriers Logistics Ltd | Transport & logistics | 2024 |
| Msnb Motion Limited | Information & communication | 2025 |
| MSQ Consulting Limited | Professional & scientific | 2022 |
| Mstadross Ltd | Real estate | 2018 |
| MSZ Cafe Ltd | Hospitality | 2019 |
| MT Electrical Installations Ltd | Construction | 2018 |
| MT Investments Group Limited | Financial services | 2025 |