| Marine Studios Arts and Culture C.I.C. | Arts & recreation | 2024 |
| Mariusz Construction Services Limited | Construction | 2018 |
| Marlborough House RTM Company Limited | Households | 2009 |
| Marlowe Property Services Limited | Other services | 2010 |
| Maroon Adventures CIC | Other services | 2026 |
| Marox Holdings Ltd | Real estate | 2019 |
| Marquette Events Ltd | Administrative & support | 2026 |
| Marsea Commercials Ltd | Professional & scientific | 2024 |
| Marsh Jointing Contractors Ltd | Construction | 2026 |
| Marshbank Estates Ltd | Professional & scientific | 2006 |
| Martini Time Ltd | Other services | 2018 |
| Marvegas Limited | Information & communication | 2012 |
| Marvellous Media Digital Ltd | Professional & scientific | 2024 |
| Marvik Ltd | Health & social care | 2021 |
| Maslow Training and Consultancy Limited | Health & social care | 2020 |
| Mason FRY Properties Ltd | Real estate | 2017 |
| Master CUT Kent Ltd | Other services | 2020 |
| Matcham Plant Hire Ltd | Financial services | 2024 |
| Mathews Management Ltd | Professional & scientific | 2019 |
| Matkit Ltd | Administrative & support | 2023 |
| Matrescence CIC | Education | 2026 |
| Maurice Blackman Limited | Construction | 1983 |
| Mavis Joan Memorial Hospital Limited | Health & social care | 2026 |
| Maxbuilt Innovations Ltd | Construction | 2025 |
| Maximus Catering Ltd | Hospitality | 2024 |
| Maynard & Barn Construction Ltd | Construction | 2018 |
| Mayuma Holdings Ltd | Financial services | 2026 |
| MC09 Limited | Construction | 2026 |
| Mcam Services Ltd | Information & communication | 2023 |
| Mccree and Daughter Limited | Real estate | 2026 |
| Mcenhill Limited | Education | 2025 |
| Mckay Building Services Ltd | Administrative & support | 2024 |
| Mckenna Enforcement Solutions Ltd | Administrative & support | 2022 |
| Mcmlxxix Ltd | Information & communication | 2019 |
| MCP Design & Print Limited | Manufacturing | 2007 |
| Mcsquared Property Limited | Real estate | 2023 |
| MD Accounting Marine Tax Services Ltd | Professional & scientific | 2020 |
| ME Fish & Chips Ltd | Hospitality | 2025 |
| Me&Sg Ltd | Wholesale & retail | 2024 |
| Meades Accounting Limited | Professional & scientific | 2017 |
| Medixis Healthcare Ltd | Administrative & support | 2024 |
| Medway Office Interiors Limited | Construction | 1981 |
| Mega Global Trade Ltd | Transport & logistics | 2018 |
| Mehmet Bay Ltd | Hospitality | 2021 |
| Mel's Home Organisation & Cleaning Company Ltd | Administrative & support | 2025 |
| Mendenhall Limited | Other services | 2006 |
| Meranti Marine Ltd | Professional & scientific | 2006 |
| Merchalicious Limited | Manufacturing | 2024 |
| Mergit Invest Ltd | Wholesale & retail | 2024 |
| Merrytime Promotions Ltd | Arts & recreation | 2018 |
| Merton Services Ltd | Professional & scientific | 2024 |
| Messiah Riff Audio Ltd. | Information & communication | 2022 |
| Metaball Ltd | Arts & recreation | 2021 |
| Meyra Fish & Chips Ltd | Hospitality | 2024 |
| MF Contemporary Build Ltd | Construction | 2020 |
| Mfbr Property 2 Ltd | Real estate | 2024 |
| Mfbr Property Ltd | Real estate | 2023 |
| MFC Investments Limited | Financial services | 2018 |
| MG Independent Trading Ltd | Public administration | 2020 |
| MH Horses Ltd | Wholesale & retail | 2021 |
| MIA of Margate Ltd | Other services | 2020 |
| MIA Papas Kitchen Ltd | Hospitality | 2022 |
| Michael Brothers (of Margate) Limited | Real estate | 1962 |
| Michael Shields Limited | Manufacturing | 2019 |
| Michberge Limited | Real estate | 2021 |
| Michelle the Mindset Coach Ltd | Administrative & support | 2023 |
| Michrock Global Limited | Construction | 2025 |
| Midea Solutions Ltd | Information & communication | 2025 |
| Mighty Margate CIC | Arts & recreation | 2025 |
| Mik's Refurbishments Ltd | Construction | 2020 |
| Miki Trans Ltd | Transport & logistics | 2014 |
| Mildon Services Limited | Real estate | 2025 |
| Mile High Scaffolding Ltd | Construction | 2016 |
| Milk First Ltd | Information & communication | 2020 |
| Millen & Co (Margate) Limited | Professional & scientific | 2017 |
| Millen & Co Limited | Professional & scientific | 2007 |
| Millen Property Limited | Households | 2021 |
| Mini Amsterdam Ltd | Wholesale & retail | 2020 |
| Mini Market Margate Limited | Wholesale & retail | 2019 |
| Minnis Bay Property Limited | Real estate | 2023 |
| Minster Food Station Ltd | Hospitality | 2023 |
| Minster Kitchen and Wardrobes Ltd | Manufacturing | 2022 |
| Mirwell Commercial Limited | Financial services | 2021 |
| Miss Green Clean Ltd | Administrative & support | 2017 |
| Miss Vintage Vicky Limited | Other services | 2024 |
| Mitchells Kitchens & Bathrooms Ltd | Construction | 2023 |
| MIX UP Meet UP Limited | Hospitality | 2024 |
| MJC Renewable Energy Ltd | Professional & scientific | 2025 |
| MK Auto Repairs Ltd | Wholesale & retail | 2016 |
| MKA Supply Ltd | Wholesale & retail | 2025 |
| MLM Electrical Contractors Ltd | Construction | 2022 |
| Mlst Solutions Ltd | Information & communication | 2022 |
| MM Events Managements Limited | Agriculture & fishing | 2025 |
| Mmsj Trans Ltd | Transport & logistics | 2022 |
| Mmtuk Policy Research Group Ltd | Professional & scientific | 2025 |
| MN Data Services Ltd | Information & communication | 2020 |
| Moat Park Properties Limited | Real estate | 2002 |
| MOB Solutions Limited | Other services | 2021 |
| Mobile Valeting Auto Perfection Ltd | Other services | 2018 |
| MOL Merch Ltd | Wholesale & retail | 2025 |