| Luma Restaurants Limited | Hospitality | 2016 |
| Lumi Play Ltd | Hospitality | 2026 |
| Luxxwavvs Ltd | Other services | 2025 |
| Lyburn and Stilton Holdings Ltd | Real estate | 2026 |
| M & M Brickwork and Building Contractors Limited | Construction | 1997 |
| M & R Property Partnership Limited | Construction | 2018 |
| M a H Courier Services Ltd | Transport & logistics | 2023 |
| M F Designs Limited | Professional & scientific | 2002 |
| M F O Holdings Limited | Professional & scientific | 2023 |
| M Horton Investments Limited | Wholesale & retail | 2013 |
| M J Rose Plumbing & Heating Ltd | Construction | 2019 |
| M R a Holdings (South) Limited | Real estate | 2022 |
| M Rhys Property Investment Limited | Real estate | 2017 |
| M W Conservatories Limited | Construction | 2016 |
| M.Gover Electrical Ltd | Construction | 2025 |
| Maar Holdings Ltd | Professional & scientific | 2016 |
| MABI99 Limited | Transport & logistics | 2020 |
| Machaan Ltd | Hospitality | 2026 |
| Macvere (Engineering) Limited | Manufacturing | 1972 |
| Madeira Roots Ltd | Hospitality | 2025 |
| Madhu RAO Limited | Professional & scientific | 2015 |
| Maglic Limited | Health & social care | 2015 |
| Magload Ltd | Manufacturing | 2018 |
| Mahantam London Limited | Wholesale & retail | 2024 |
| Mainline 1 Ltd | Real estate | 2020 |
| Mainline 2 Ltd | Real estate | 2020 |
| Make IT Memorable Ltd | Other services | 2024 |
| Making Space for Crafts Ltd | Arts & recreation | 2002 |
| Malama ARK Ltd | Wholesale & retail | 2019 |
| Mallard Accounting Ltd | Professional & scientific | 2019 |
| Marine Electrical Ltd | Construction | 2018 |
| Marine Flow Products Ltd | Wholesale & retail | 2020 |
| Market Spice Limited | Hospitality | 2025 |
| Marlene Ruby Limited | Construction | 2019 |
| Marsh Plant Hire Limited | Administrative & support | 1965 |
| Massalla Lounge Ltd | Hospitality | 2018 |
| Mastercue Limited | Arts & recreation | 1998 |
| Masters in Beauty Ltd | Wholesale & retail | 2021 |
| Matthew Trust UK | Real estate | 2008 |
| Mays Estate Agents Ltd | Real estate | 2024 |
| MBI Property Group Ltd | Real estate | 2023 |
| MCG Building and GAS Services Limited | Energy | 2019 |
| MCI Group UK Limited | Administrative & support | 1986 |
| MCI UK Limited | Administrative & support | 1977 |
| Mclqualitech Ltd | Professional & scientific | 2026 |
| Meddent Global Solutions Ltd | Manufacturing | 2025 |
| Melia Properties Ltd | Construction | 2024 |
| Memtech Solutions Ltd | Information & communication | 2026 |
| Meridian GAS Services Limited | Construction | 2021 |
| Merritt Decorating Contractors Limited | Construction | 2014 |
| Meta Marketing (UK) Ltd | Wholesale & retail | 2012 |
| Metal Craft Fabrications (Havant) Limited | Manufacturing | 2003 |
| MG Imaging Ltd | Wholesale & retail | 2011 |
| MGE Resources Ltd | Public administration | 2023 |
| MGN Property Services Ltd | Construction | 2019 |
| MI Property Services Group Limited | Construction | 2019 |
| MIA Nails Havant Limited | Other services | 2024 |
| Microsec Limited | Information & communication | 1979 |
| Middlewood Garden Maintenance Ltd | Administrative & support | 2023 |
| Mike & JON Limited | Real estate | 2023 |
| Mike Ring Developments Limited | Professional & scientific | 2024 |
| Mike Ring Industries Limited | Manufacturing | 2024 |
| Mila Developments Ltd | Construction | 2020 |
| Mills Composites Limited | Manufacturing | 2024 |
| Milners Outdoors Ltd | Wholesale & retail | 2025 |
| Mimi's Organics Ltd | Wholesale & retail | 2013 |
| Mind Mirage Apps Ltd | Information & communication | 2026 |
| Mintstyle Limited | Professional & scientific | 2001 |
| Mipa Paints Limited. | Manufacturing | 1986 |
| Miqu Ltd | Professional & scientific | 2015 |
| Missionkraft Limited | Manufacturing | 2011 |
| Mixed Golf Events Ltd | Arts & recreation | 2025 |
| MJH Spa and Wellbeing Limited | Professional & scientific | 2019 |
| MKZ Capital Ltd | Financial services | 2025 |
| Mlay Consult Limited | Professional & scientific | 2024 |
| Mma-Max Ltd | Administrative & support | 2011 |
| MMD Media Group Ltd | Professional & scientific | 2025 |
| MMP Electrovibe UK Limited | Professional & scientific | 2012 |
| Mold GB Services Ltd | Wholesale & retail | 2018 |
| Money Shop Direct Limited | Financial services | 2010 |
| Monkeydribble Films Ltd | Information & communication | 2021 |
| Mono DC Limited | Professional & scientific | 2012 |
| Mono ZG Limited | Professional & scientific | 2012 |
| Monolution Holdings Limited | Professional & scientific | 2009 |
| Monolution Limited | Manufacturing | 2006 |
| Monotek (UK) Limited | Construction | 2018 |
| Monsters INK HQ Limited | Wholesale & retail | 2014 |
| Morgan & Morgan Medical Services Limited | Health & social care | 2022 |
| Motatalk Garage Services Ltd | Manufacturing | 2012 |
| Motorent Limited | Administrative & support | 2005 |
| Motorom Ltd | Wholesale & retail | 2016 |
| Mountbureau Group Limited | Professional & scientific | 2025 |
| Mousetrap (Sussex) Limited | Wholesale & retail | 2003 |
| MP ALL Safety Ltd | Professional & scientific | 2024 |
| MR & MRS Pickles Ltd | Hospitality | 2024 |
| MR Floorsure (Southern) Limited | Construction | 2015 |
| Ms.Aestheticsuk Ltd | Other services | 2022 |
| Msba Limited | Professional & scientific | 2025 |
| Mulberry Building Contractors Ltd. | Construction | 1998 |
| Multi Serv (Group) Limited | Financial services | 2012 |