| MON Choubidou Ltd | Wholesale & retail | 2025 |
| Mona Translates Ltd | Administrative & support | 2014 |
| Monarch Electro Diesel Limited | Wholesale & retail | 1993 |
| Monarculu Agent Ltd | Information & communication | 2024 |
| Mondas Media International Limited | Professional & scientific | 2016 |
| Mondosa Ltd | Professional & scientific | 2017 |
| Mondturn Limited | Wholesale & retail | 1985 |
| Monesha Care Limited | Health & social care | 2015 |
| Money 4 Leisure Ltd | Professional & scientific | 2012 |
| Money Debt & Credit Group Limited | Financial services | 2006 |
| Moneyrow Homes Ltd | Real estate | 2026 |
| Moneyrow Property Ltd | Real estate | 2026 |
| Monfared Pizza Ltd | Hospitality | 2018 |
| Monfy Media Ltd | Information & communication | 2026 |
| Monica Garcia Consulting Limited | Professional & scientific | 2020 |
| Monica Joita Ltd | Other services | 2018 |
| Monica''s Maid Services Ltd | Other services | 2006 |
| Monica's Cleaning Services Ltd | Administrative & support | 2010 |
| Monica's Maid Services (Watford) Ltd | Administrative & support | 2018 |
| Monica's Maintenance Services Ltd | Administrative & support | 2016 |
| Monkitech PVT Ltd | Information & communication | 2025 |
| Monreve AI Ltd | Professional & scientific | 2024 |
| Monreve Marn Ltd | Financial services | 2024 |
| Monroe Capital Investments Limited | Financial services | 2026 |
| Monroe Developments Ltd | Real estate | 2020 |
| Monroe Investments LLP | | 2017 |
| Monroe Properties Ltd | Real estate | 2017 |
| Monss Ltd | Wholesale & retail | 2026 |
| Monster Joysticks Ltd | Manufacturing | 2017 |
| Montagu Court Investments Ltd | Real estate | 2022 |
| Montana Development Solutions Limited | Administrative & support | 2018 |
| Montana Dining Company Ltd | Hospitality | 2026 |
| Monte Trans Limited | Transport & logistics | 2023 |
| Monteal Ltd | Real estate | 2010 |
| Montero Properties Ltd | Real estate | 2024 |
| Monterra Group Ltd | Construction | 2025 |
| Montpelier Rise Management Company Limited | Households | 1999 |
| Montvue Estates Ltd | Real estate | 2025 |
| Monuhk Limited | Wholesale & retail | 2020 |
| Monumental Post Ltd | Information & communication | 2014 |
| Mood Cafe Ltd | Hospitality | 2021 |
| Moodyz World Ltd | Other services | 2024 |
| Moon (LDN) Ltd | Hospitality | 2024 |
| Moon and Spoon Limited | Professional & scientific | 1996 |
| Moon and Stars Limited | Professional & scientific | 1996 |
| Moon Build Ltd | Construction | 2026 |
| Moon on the Hill Limited | Professional & scientific | 1996 |
| Moon Rabbit Group Ltd | Wholesale & retail | 2021 |
| Moonframe Ltd | Wholesale & retail | 2026 |
| Moonlight Chakras Limited | Wholesale & retail | 2023 |
| Moonlit Pictures Ltd | Information & communication | 2025 |
| MOOR2LIFE Ltd | Manufacturing | 2025 |
| Moore, Scott and Hale Management Company Limited | Real estate | 1980 |
| Moorsom & Co Limited | Hospitality | 1959 |
| Moosajie Consulting Ltd | Professional & scientific | 2016 |
| Moosvi IT Limited | Information & communication | 2015 |
| Moove Supply Chain Ltd | Professional & scientific | 2022 |
| Moral Design Ltd | Professional & scientific | 2016 |
| Morale Solutions Ltd | Professional & scientific | 2009 |
| Moray House Residents Association Limited | Other services | 1973 |
| More Park Ltd | Hospitality | 2011 |
| Morecon Limited | Professional & scientific | 2012 |
| Morell Cheng Ltd | Information & communication | 2024 |
| Moreno Healthcare Ltd | Health & social care | 2026 |
| Moreno-Rehabservices Ltd | Health & social care | 2023 |
| Morgan Entertainment Limited | Arts & recreation | 2024 |
| Morgan Jamieson Services Ltd. | Other services | 2014 |
| Morgan Rice Art Ltd | Arts & recreation | 2026 |
| Moroccan and Arab Exhibition Ltd | Administrative & support | 2022 |
| Moromizato Ltd | Information & communication | 2023 |
| Morpheus Caregroup Ltd | Health & social care | 2019 |
| Morris Consultancy Services Limited | Information & communication | 2005 |
| Morrisroe Demolition Limited | Construction | 1967 |
| Morta Enterprises Limited | Information & communication | 2014 |
| Mortgage for ME Ltd | Financial services | 2023 |
| Mortgage Knight Limited | Financial services | 2023 |
| Mortgages Warehouse Ltd | Financial services | 2012 |
| Mortgagetek Ltd | Financial services | 2014 |
| Moruz Ltd | Wholesale & retail | 2017 |
| Mosab Cartify Ltd | Wholesale & retail | 2026 |
| Mosale Enterprises Limited | Construction | 2013 |
| Mosflowline Ltd. | Other services | 2009 |
| Moss Free Xpert Ltd | Administrative & support | 2024 |
| Mostar Property Ltd | Real estate | 2016 |
| MOT Direct to YOU Ltd | Manufacturing | 2015 |
| Motee London Limited | Wholesale & retail | 2016 |
| Motion Commerce Ltd | Information & communication | 2008 |
| Motion-Friendly Ltd | Transport & logistics | 2020 |
| Motobodywork Ltd | Wholesale & retail | 2026 |
| Motor Consulting and Marketing Limited | Health & social care | 2016 |
| Motor LAB Ltd | Wholesale & retail | 2025 |
| Motor MOB Autos Ltd | Wholesale & retail | 2025 |
| Motor Part Group Limited | Wholesale & retail | 2021 |
| Motor Services Watford Ltd | Wholesale & retail | 2012 |
| Motor Universe Limited | Wholesale & retail | 2025 |
| Motori UK Ltd | Wholesale & retail | 2022 |
| Motormiles Limited | Wholesale & retail | 2017 |
| Motov Ltd | Information & communication | 2020 |
| Mount Park Investments Limited | Real estate | 2016 |
| Mount Park Partnership Ltd | Real estate | 2020 |