| MDF Engineering UK Limited | Wholesale & retail | 2005 |
| MDR Electrical(Kent) Ltd | Construction | 2010 |
| Mead & Mcgee Limited | Construction | 2008 |
| MED Clean Domestic Limited | Administrative & support | 2017 |
| Meddy's ROH Ltd | Hospitality | 2025 |
| Medispa by M.R Ltd | Administrative & support | 2019 |
| Megjestic Properties LLP | | 2021 |
| Melior Holdings Ltd | Real estate | 2024 |
| Melissa Viviers Ltd | Professional & scientific | 2015 |
| Mental Health United Thanet C.I.C. | Arts & recreation | 2025 |
| Meopham Mini Skips Ltd | Water & waste | 2021 |
| Mercury North Distribution Limited | Professional & scientific | 2011 |
| MF Security Solutions Ltd | Administrative & support | 2023 |
| Mfmorris Statistics Limited | Professional & scientific | 2026 |
| MFP Design Consultants Ltd | Professional & scientific | 2025 |
| MH Media Global Ltd | Information & communication | 2011 |
| Micare Official Ltd | Wholesale & retail | 2026 |
| Michael Hillary Tax Consultant Limited | Professional & scientific | 2022 |
| Michael J Davis Limited | Financial services | 2021 |
| Mikio Limited | Hospitality | 2023 |
| Milanov 81 Limited | Transport & logistics | 2019 |
| Mill Inn Ltd | Hospitality | 2023 |
| Mills Group Ltd | Financial services | 2025 |
| Millykay Couture Limited | Manufacturing | 2026 |
| Milton Ashbury Limited | Real estate | 1998 |
| Mimi Activewear Limited | Wholesale & retail | 2026 |
| Mimi Event Hire Ltd | Hospitality | 2019 |
| Mindfulness at Work Limited | Administrative & support | 2011 |
| Mini Tennis Insight Limited | Arts & recreation | 2023 |
| Minibots Limited | Information & communication | 2025 |
| Minnis Bay Management Company Limited | Real estate | 2005 |
| Minnis Road Management Company Limited | Administrative & support | 2005 |
| Minnitron Limited | Manufacturing | 1962 |
| Minster Athenian Ltd | Hospitality | 2024 |
| Minster Beautique Ltd | Other services | 2024 |
| Minster Chinese Limited | Hospitality | 2024 |
| Minster Lodge (Ramsgate) Limited | Households | 2004 |
| Minster MOT & Repair Centre Ltd | Wholesale & retail | 2018 |
| Mischievous Theatre CIC | Arts & recreation | 2012 |
| Mist Hydration Ltd | Wholesale & retail | 2025 |
| Mitchell Gifts Ltd | Wholesale & retail | 2026 |
| Mixies Combination Cereal Ltd | Manufacturing | 2025 |
| MJ Buy & Sell Ltd | Wholesale & retail | 2025 |
| Mj's Cleaning Ltd | Administrative & support | 2024 |
| MJL Plastering Ltd | Construction | 2022 |
| MJP Systems Ltd | Information & communication | 2026 |
| MJT Computing Limited | Administrative & support | 2017 |
| MK Account Services Ltd | Extraterritorial | 2019 |
| MK Compliance Ltd | Professional & scientific | 2018 |
| MKR Trading Limited | Wholesale & retail | 2024 |
| ML Development Deal Ltd | Construction | 2023 |
| MLG Promotions Limited | Professional & scientific | 2024 |
| MM Flooring (Kent) Limited | Wholesale & retail | 2021 |
| MMA Garage Ltd | Wholesale & retail | 2025 |
| Mmfb Property Limited | Real estate | 2025 |
| MNH Windows & Conservatories Ltd | Construction | 2022 |
| Mnsc Projects Limited | Administrative & support | 2025 |
| Modern Surface Ltd | Professional & scientific | 2021 |
| Modern Trade Materials Ltd. | Wholesale & retail | 2023 |
| Moducore Consulting Ltd | Professional & scientific | 2024 |
| Mollys Cars Ltd | Administrative & support | 2025 |
| Momentum Healthcare Ltd | Health & social care | 2019 |
| Momentum Installations Ltd | Construction | 2023 |
| Monarch Estate Lettings Ltd | Real estate | 2025 |
| Monkton BBQ House Ltd | Hospitality | 2025 |
| Monkton Carpets Limited | Wholesale & retail | 2020 |
| Monkton Contracts Limited | Administrative & support | 2008 |
| Monkton Manor Residents Company Limited | Households | 1983 |
| Monocstune Mews Limited | Households | 2016 |
| Montecristo Bay Ltd | Real estate | 2012 |
| Moochdesign Limited | Arts & recreation | 2002 |
| Mood Indigo Ltd | Arts & recreation | 2017 |
| Moore & Moore Coach House Property Ltd | Real estate | 2020 |
| More Than US Ltd | Real estate | 2021 |
| Morena's Nail & Beauty Salon's Limited | Other services | 2011 |
| Morgan Bodyworks Ltd | Wholesale & retail | 2019 |
| Morgan Trussing Limited | Manufacturing | 2002 |
| Morliss Fast Food Ltd | Hospitality | 2021 |
| Mortgage Services 4U Ltd | Financial services | 2008 |
| Mortimers Restaurant Limited | Hospitality | 2008 |
| Mother Brain Ltd | Arts & recreation | 2022 |
| Mother Ultimate Ltd | Professional & scientific | 2019 |
| Mount Music Management Ltd | Real estate | 2013 |
| MP Kent Limited | Other services | 2019 |
| MPG Properties (Thanet) Limited | Real estate | 2003 |
| MPJ Property Management Limited | Administrative & support | 2021 |
| MPZ Group Ltd | Construction | 2024 |
| MR Crustie of Broadstairs Ltd | Wholesale & retail | 2011 |
| MR Holistic Care UK Ltd | Administrative & support | 2023 |
| MR Tripson Limited | Professional & scientific | 2016 |
| MRD Electrical Ltd | Construction | 2023 |
| Mrjm Business Ltd | Hospitality | 2026 |
| MSA E-Commerce Limited | Wholesale & retail | 2021 |
| MSD Wall Coatings Ltd | Construction | 2023 |
| MSN Transport Kent Ltd | Transport & logistics | 2022 |
| MTH Electrical Limited | Construction | 2013 |
| Mthm Rail Ltd | Construction | 2025 |
| Mtstudios Limited | Information & communication | 2004 |
| MUC Global Ltd | Wholesale & retail | 2026 |
| Mundostra Ltd | Information & communication | 2024 |