| Momac Films Ltd | Wholesale & retail | 2003 |
| Momo Gifts Ltd | Wholesale & retail | 2014 |
| Monatown Limited | Administrative & support | 1996 |
| Moncleaning Ltd | Administrative & support | 2026 |
| Monestro LLC FZ Ltd | Energy | 2025 |
| Monetix Ltd | Information & communication | 2022 |
| Money Collectors Limited | Administrative & support | 2021 |
| Moneyrepublic Ltd | Information & communication | 2019 |
| Monier Road Hackney Wick Management Company Limited | Real estate | 2016 |
| Monk PR Ltd | Administrative & support | 2005 |
| Monkey Business Entertainment Limited | Arts & recreation | 2012 |
| Monmore Grange Management Company Limited | Professional & scientific | 2005 |
| Montag Estate Limited | Construction | 2008 |
| Montcler Limited | Administrative & support | 2023 |
| Monte Cristo Asset Management Limited | Professional & scientific | 2023 |
| Montevecchi Transport Ltd | Transport & logistics | 2026 |
| Montfort Management Ltd | Real estate | 2021 |
| Montreaux Bromley Developments Limited | Construction | 2022 |
| Montreaux Hythe Ltd | Real estate | 2016 |
| Montreaux Luxe Limited | Construction | 2019 |
| Montza Ltd | Manufacturing | 2024 |
| Monumental Properties Ltd | Real estate | 2023 |
| Moonalabs Ltd | Manufacturing | 2021 |
| Moonbeam Health Ltd | Professional & scientific | 2022 |
| Moons Grill & Kebab House Limited | Hospitality | 2018 |
| Moonshot Films Limited | Information & communication | 2019 |
| Moonshot One Limited | Information & communication | 2022 |
| Moonwalker Films Ltd | Information & communication | 2023 |
| Moorcroft Builders Limited | Construction | 2024 |
| Mopa Properties Limited | Real estate | 2016 |
| Mordan Estates Ltd | Real estate | 2024 |
| Mordconstruct Ltd | Construction | 2012 |
| Moreham Wood Limited | Wholesale & retail | 2023 |
| Morewell Building Ltd | Construction | 2014 |
| Morgan Long Fine Art Ltd | Other services | 2023 |
| Morident Ltd | Health & social care | 2024 |
| Morley Finco Limited | Real estate | 2014 |
| Morley Income Co Limited | Real estate | 2014 |
| Morprop Ltd | Financial services | 2022 |
| Morris Investments Limited | Real estate | 1998 |
| Morrisroe Group Limited | Professional & scientific | 2006 |
| Morrisroe Management Limited | Professional & scientific | 2010 |
| Mortlake Limited | Wholesale & retail | 2000 |
| MOS Law Ltd | Professional & scientific | 2024 |
| MOS Properties Limited | Real estate | 2020 |
| MOS Solutions Ltd | Health & social care | 2018 |
| Moscato Transportation LLP | | 2015 |
| Mosha Ltd | Professional & scientific | 2020 |
| Mosiana Ltd | Real estate | 2020 |
| Mosmags Experts Ltd | Professional & scientific | 2020 |
| Moss Hall Developments Limited | Construction | 2006 |
| Moss Hall Holdings Ltd | Financial services | 2022 |
| Moss Retail Group Ltd | Wholesale & retail | 2026 |
| Motcombe Investments Limited | Construction | 2024 |
| Moterra Ltd | Information & communication | 2024 |
| Motiveminds Consulting UK Ltd | Information & communication | 2022 |
| Motor Supermarket Limited | Wholesale & retail | 2012 |
| Motortek Limited | Wholesale & retail | 2008 |
| Mount Street Capital Assets Limited | Real estate | 2014 |
| Mountain (Sunset) Limited | Administrative & support | 2014 |
| Mountain Capital Limited | Hospitality | 2006 |
| Mountport Limited | Information & communication | 2000 |
| Mouton Services Limited | Administrative & support | 2026 |
| Move in Silence Ltd | Wholesale & retail | 2025 |
| Movie Drapes Ltd | Construction | 2023 |
| Moviebytes Ltd | Information & communication | 2016 |
| Mowbray Carpets Limited | Wholesale & retail | 1993 |
| MPA Business Services Limited | Professional & scientific | 2016 |
| Mpbo Projects Ltd | Construction | 2017 |
| Mpbo Properties Limited | Real estate | 2020 |
| Mpbo York Apartments Limited | Real estate | 2025 |
| MPD Holdings Ltd | Transport & logistics | 2020 |
| Mpep Properties Ltd | Real estate | 2025 |
| MPG Developments Limited | Financial services | 2021 |
| MPV Medical Ltd | Health & social care | 2022 |
| MR Andre Ismail Ltd | Health & social care | 2023 |
| MR Food Halal Ltd | Hospitality | 2026 |
| MR Pdnewman Limited | Hospitality | 2026 |
| MR. Bagel's Limited | Professional & scientific | 2009 |
| Mrbh Limited | Hospitality | 2025 |
| MRK 98 Ltd | Transport & logistics | 2022 |
| MRK Capital Holdings Limited | Financial services | 2025 |
| MRM Builders Limited | Construction | 2008 |
| MRS Bite Ltd | Manufacturing | 2023 |
| Mrvr Property Ltd | Real estate | 2025 |
| MS Comm Limited | Information & communication | 2007 |
| MS Fleet Services Ltd | Wholesale & retail | 2019 |
| MSB Creative Limited | Arts & recreation | 2013 |
| Msdp Limited | Health & social care | 2025 |
| MSK Medical Services Ltd | Health & social care | 2009 |
| MSK Property Ltd | Real estate | 2020 |
| MT25 Ltd | Construction | 2025 |
| Mtaa UK Limited | Professional & scientific | 2020 |
| MTE Medical Limited | Health & social care | 2022 |
| Mtjb Engineering Ltd | Professional & scientific | 2017 |
| MTK Events Ltd | Administrative & support | 2023 |
| Mtsm Holdings Ltd | Real estate | 2018 |
| Muhammad Liyawdeen Ltd | Health & social care | 2025 |
| Muhism Ltd | Financial services | 2024 |
| Mukherjee Limited | Health & social care | 2011 |