| Meads Scientific Ltd | Professional & scientific | 2025 |
| Meads Village Allotments CIC | Real estate | 2019 |
| Meadscroft Limited | Households | 2005 |
| Meadsway Management Company Limited | Households | 1992 |
| Mealsonwheelstoyou Ltd | Hospitality | 2025 |
| Meatex Holdings Ltd | Wholesale & retail | 2012 |
| Meatex Ltd | Wholesale & retail | 2012 |
| Mech-Elec Group Ltd | Administrative & support | 2019 |
| Mechanical & Electrical Handling Services Limited | Construction | 2007 |
| MED Therapeutics Limited | Professional & scientific | 2018 |
| Medaivate Limited | Professional & scientific | 2025 |
| Medelite Ltd | Health & social care | 2025 |
| Medeng PVT Ltd | Education | 2024 |
| Medi WAV Ltd | Transport & logistics | 2020 |
| Media CVS Ltd | Other services | 2020 |
| Media Marquee Limited | Professional & scientific | 2025 |
| Mediabite Group Limited | Professional & scientific | 2019 |
| Medic Tour Damis Ltd | Wholesale & retail | 2010 |
| Medical Aesthetic Solutions Ltd | Health & social care | 2021 |
| Medical Smart Marketing Ltd | Professional & scientific | 2016 |
| Medicine for ALL Ltd | Administrative & support | 2017 |
| Medvy Ltd | Health & social care | 2023 |
| Medway City Roofing Ltd | Construction | 2022 |
| MEE Utilities Ltd | Construction | 2022 |
| Meeware Echo Ltd | Professional & scientific | 2022 |
| Meghan and Becky Ltd | Manufacturing | 2017 |
| Mehl Dentistry Limited | Health & social care | 2024 |
| Mehl Holdings Limited | Financial services | 2024 |
| Mehl Limited | Health & social care | 2010 |
| Mehl Properties Limited | Construction | 2024 |
| Mehra Autos Limited | Wholesale & retail | 2017 |
| Mehra Services Limited | Professional & scientific | 2019 |
| Meix Fluat Limited | Real estate | 2022 |
| Meldarosa Properties Limited | Real estate | 2010 |
| Melting Point Media Limited | Information & communication | 2014 |
| Memzbarber Limited | Other services | 2023 |
| Merch Hub Limited | Other services | 2009 |
| Mercor Limited | Wholesale & retail | 2017 |
| Meridian Construction Management Ltd | Construction | 2026 |
| Meridian Court (Eastbourne) RTM Company Limited | Households | 2017 |
| Meridian Prime Limited | Professional & scientific | 2004 |
| Meridian Social Work Limited | Extraterritorial | 2018 |
| Meridiem Services Ltd | Real estate | 2019 |
| Merleburgh Place Residents Management Company Limited | Households | 2025 |
| Merlin HR Solutions Limited | Administrative & support | 2012 |
| Merlinlink Limited | Administrative & support | 2009 |
| Merlswood Residents' Association Limited | Households | 1970 |
| Merlynn Management (Eastbourne) Limited | Households | 1979 |
| Mermaid Dental Care Limited | Health & social care | 2010 |
| Merrystead Dental Ltd | Health & social care | 2021 |
| Mert 2011 Ltd | Hospitality | 2024 |
| Merthur Limited | Professional & scientific | 2012 |
| Merton Court (Eastbourne) Management Company Ltd | Households | 2014 |
| Metal Powder Emergence Limited | Manufacturing | 2021 |
| Metal Recycling Limited | Water & waste | 1997 |
| Metal Recycling Sussex Limited | Transport & logistics | 2011 |
| Metal Teeth Threads Limited | Wholesale & retail | 2023 |
| Metamodern Medicine CIC | Education | 2023 |
| Metamorphosis Business Projects Ltd | Real estate | 2023 |
| Metavita Ltd | Information & communication | 2022 |
| Meteoric Games Ltd | Wholesale & retail | 2011 |
| Metropolis Craft Limited | Hospitality | 2016 |
| Mevp Limited | Wholesale & retail | 2018 |
| Mewetts 9-12 (Management) Limited | Households | 2006 |
| Mewetts Court (Management) Limited | Households | 2005 |
| Mexbourne Property Holdings Limited | Real estate | 2025 |
| MF Construction & Developments Limited | Construction | 2020 |
| Mfcdars Limited | Administrative & support | 2017 |
| Mfch Ltd | Wholesale & retail | 2024 |
| Mford Engineering Limited | Manufacturing | 2024 |
| MG Locations Ltd | Administrative & support | 2025 |
| MG Studio Ltd | Manufacturing | 2015 |
| MG Sussex Limited | Extraterritorial | 2024 |
| MGC Consultancy Limited | Wholesale & retail | 2003 |
| Mgrh Holdings Ltd | Real estate | 2020 |
| MGT Investments Limited | Real estate | 2017 |
| MGW Building Ltd | Construction | 2024 |
| MH Autowerke Ltd | Wholesale & retail | 2023 |
| MHN Investments Limited | Real estate | 2024 |
| MIA Real Estates Ltd | Real estate | 2024 |
| Mian Digital Empire Ltd | Wholesale & retail | 2025 |
| Mibia Ltd | Health & social care | 2023 |
| Michael Jones Building Solutions Limited | Construction | 2024 |
| Michael Legg Ltd | Construction | 2015 |
| Michael Leigh Management Ltd | Professional & scientific | 2026 |
| Michaela Edwardes Limited | Arts & recreation | 2008 |
| Michel Grove House RTM Company Limited | Households | 2007 |
| Mick Hannam Plastering Services Limited | Construction | 2012 |
| Middle Aged Vandals Ltd | Arts & recreation | 2025 |
| Middlehouse.Shop Ltd | Wholesale & retail | 2024 |
| Miderma Ltd | Health & social care | 2018 |
| Midiservices Ltd | Information & communication | 1992 |
| Midori Wellness Ltd. | Administrative & support | 2019 |
| Miftari Developments Limited | Real estate | 2020 |
| Miga Property Group Ltd | Real estate | 2025 |
| Mighty Micky's Limited | Other services | 2025 |
| Mightyfist England Limited | Wholesale & retail | 2014 |
| Miha's Cafe Ltd | Hospitality | 2019 |
| Mihk Solutions Ltd | Information & communication | 2018 |
| Mikani Flex Limited | Professional & scientific | 2025 |