| Mokko Logistics and Transport Ltd | Transport & logistics | 2024 |
| Mokwena Ltd | Health & social care | 2019 |
| Molecular Mixology Limited | Hospitality | 2018 |
| Molim.Co.Uk Ltd | Professional & scientific | 2021 |
| Mollie & Sky Ltd | Wholesale & retail | 2020 |
| Molly's Bakehouse Ltd | Manufacturing | 2024 |
| Momentum Marine Limited | Professional & scientific | 2019 |
| Momma's Curbside Kitchen Ltd | Hospitality | 2026 |
| MON Calliste Group Limited | Information & communication | 2015 |
| Mona Pouya Ltd | Hospitality | 2016 |
| Monahan Roofing Ltd | Construction | 2022 |
| Monahookings Ltd | Real estate | 2026 |
| Monarch Bar & Restaurant Ltd | Hospitality | 2026 |
| Monarch Cocktail Bar Limited | Hospitality | 2019 |
| Monarch International Solutions Ltd | Water & waste | 2014 |
| Monarch Oxford Street Ltd | Hospitality | 2026 |
| Moncea Ltd | Transport & logistics | 2017 |
| Mondaaay Limited | Other services | 2024 |
| Mondo Line Business Ltd | Transport & logistics | 2016 |
| Monex Market Limited | Professional & scientific | 2018 |
| Money Management Group (UK) Ltd | Wholesale & retail | 1994 |
| Moneysprite Solent Limited | Financial services | 2007 |
| Monics & Co Ltd | Administrative & support | 2025 |
| Monika Ltd | Transport & logistics | 2025 |
| Monil Trans Ltd | Transport & logistics | 2022 |
| Monitery Ltd | Information & communication | 2025 |
| Monitor and Screen Rental Ltd | Administrative & support | 2009 |
| Monix Expeditions Limited | Administrative & support | 2015 |
| Monkerton Heat Company Limited | Energy | 2015 |
| Monkey Consultant Limited | Professional & scientific | 2022 |
| Monkey Office Ltd | Extraterritorial | 2010 |
| Monks Court Management Company (Lymington) Limited | Households | 1999 |
| Monma Limited | Other services | 2020 |
| Monmiral LLP | | 2023 |
| Monnatally Ltd | Transport & logistics | 2011 |
| Monomyth Limited | Professional & scientific | 2025 |
| Monroes Hair and Beauty Limited | Other services | 2024 |
| Monros of Ludgershall Limited | Construction | 1954 |
| Monsieur Monkey Limited | Administrative & support | 2011 |
| Monster Aviation Limited | Transport & logistics | 2020 |
| Monster Camper Limited | Wholesale & retail | 2022 |
| Monster Wheels Limited | Wholesale & retail | 2022 |
| Monsterwraps Limited | Wholesale & retail | 2014 |
| Montaj Limited | Information & communication | 2019 |
| Montana Ltd | Construction | 2020 |
| Monteith Brown Upholstery Limited | Extraterritorial | 2020 |
| Montfort Court Management Limited | Households | 1995 |
| Monthorn Limited | Professional & scientific | 2007 |
| Montiara & ROH International Resources Ltd | Administrative & support | 2021 |
| Monture Limited | Financial services | 2025 |
| Monument Development Management Ltd | Professional & scientific | 2014 |
| Monux Limited | Wholesale & retail | 2026 |
| MOO at the Barnyard Ltd | Hospitality | 2024 |
| Mood Boxes Ltd | Wholesale & retail | 2021 |
| Moody &Webb Limited | Construction | 2023 |
| Moody Goat Ltd | Hospitality | 2026 |
| Mooka Ltd | Wholesale & retail | 2011 |
| Mooka Wholesale Ltd | Wholesale & retail | 2017 |
| Moon Water Treasures Ltd | Wholesale & retail | 2020 |
| Moonaz Limited | Wholesale & retail | 2024 |
| Moonduster Ltd | Hospitality | 2011 |
| Moonfleet Advisory Ltd | Professional & scientific | 2020 |
| Moonlight Real Estate Ukeig | | 2014 |
| Moonlightworks Ltd | Manufacturing | 2021 |
| Moonlit Forest Ltd | Extraterritorial | 2015 |
| Moonworks IT Ltd | Information & communication | 2012 |
| Moor Street Local Centre Management Company Limited | Households | 2006 |
| Moore Care & Support Limited | Health & social care | 2004 |
| Moore Love Ltd | Other services | 2020 |
| Moore Pharma Ltd | Professional & scientific | 2018 |
| Moore Than Sandwiches Limited | Hospitality | 2013 |
| Moore Wholesale Ltd | Wholesale & retail | 2026 |
| Moores Electrical Services Ltd | Construction | 2017 |
| Moorlands Guesthouse Ltd | Hospitality | 2025 |
| Moorside Office Limited | Wholesale & retail | 2009 |
| Moramilo Ltd | Construction | 2025 |
| Morandale Limited | Wholesale & retail | 2021 |
| Morash Limited | Wholesale & retail | 2025 |
| Moray Marine Solutions Ltd | Transport & logistics | 2018 |
| More Carpentry Ltd | Construction | 2019 |
| More Than Hair Ltd | Other services | 2021 |
| More Than Safety Limited | Wholesale & retail | 1988 |
| Morebury Limited | Wholesale & retail | 2002 |
| Moreno Trans Logistic Ltd | Transport & logistics | 2025 |
| Moresby Recruitment Ltd | Administrative & support | 2020 |
| Morestead Change Ltd | Other services | 2024 |
| Morestead Homes Limited | Construction | 2023 |
| Moreton Gohl Limited | Professional & scientific | 2015 |
| Moretoproperties Ltd | Real estate | 2025 |
| Morgan FIC Limited | Real estate | 2024 |
| Morgan Land Limited | Construction | 2001 |
| Morgan's Hair Limited | Other services | 2023 |
| Morgan-Knox Limited | Real estate | 2011 |
| Morgans Movers Ltd | Transport & logistics | 2023 |
| Morgate SPV Ltd | Real estate | 2025 |
| Morningside Projects Ltd | Real estate | 2021 |
| Morribrook Investments Limited | Real estate | 1955 |
| Morris Sinclair Recruitment Ltd | Administrative & support | 2017 |
| Morrison Plumbing and Heating Ltd | Construction | 2023 |
| Morriss Building Developments Limited | Construction | 2015 |