| Marbed Ltd | Other services | 2014 |
| Marbourne Chase (Lane END) Management Company Limited | Households | 2013 |
| Marchington Consulting Limited | Professional & scientific | 2020 |
| Marchington House RTM Company Limited | Households | 2017 |
| Marcons Ltd | Professional & scientific | 2008 |
| Marcor Management Limited | Professional & scientific | 2024 |
| Maresfield Residents Management Company Limited | Households | 2022 |
| Maria White Ltd | Health & social care | 2014 |
| Mariadb UK Ltd | Administrative & support | 2022 |
| Marianne Hall Consulting Ltd | Professional & scientific | 2025 |
| Mariano Ltd | Information & communication | 2012 |
| Marie Beauty Limited | Other services | 2019 |
| Market Fresh Fruit N Vegetables Trader Limited | Wholesale & retail | 2025 |
| Market Lane Management Limited | Households | 1990 |
| Marks Sparks Limited | Construction | 2022 |
| Marlow Brewery Estate Management Company Ltd | Households | 1997 |
| Marlow House Residents Limited | Households | 2003 |
| Marlow Road Residents Management Company Limited | Households | 2018 |
| Marmara Grill & Bar Ltd | Hospitality | 2018 |
| Marmat Ltd | Transport & logistics | 2026 |
| Marshalls Secretaries Ltd | Extraterritorial | 2015 |
| Martin & Bente Property Services Limited | Households | 2025 |
| Martin Denny Management Limited | Arts & recreation | 2002 |
| Marvel Tiles Ltd | Construction | 2020 |
| Marvell Glass Ltd | Construction | 2019 |
| Marvell Stone Ltd | Construction | 2021 |
| Mascot Makers Ltd | Wholesale & retail | 2015 |
| Mason Wills Commercial Limited | Real estate | 2025 |
| Mason Wills Limited | Real estate | 2019 |
| Master Chef Takeaway Limited | Hospitality | 2022 |
| Master Hairstyles Ltd | Other services | 2023 |
| Masterwell Ltd | Information & communication | 2020 |
| MAT Fabrications Ltd | Manufacturing | 2013 |
| Matt Yeoson Design Ltd | Professional & scientific | 2022 |
| Matthew Potter Professional Golf Shop Limited | Wholesale & retail | 2023 |
| Maurice Academy Limited | Professional & scientific | 2025 |
| Mavado Holding Limited | Financial services | 2020 |
| Maverick Studios Limited | Information & communication | 2021 |
| Mawdsley Financial Services Ltd | Financial services | 2022 |
| Mawlaw 376 Limited | Professional & scientific | 1997 |
| Maxrete Ltd | Wholesale & retail | 2021 |
| Maxv Media Ltd | Information & communication | 2012 |
| Maybach Building & Property Maintenance Ltd | Construction | 2020 |
| Maybach Group Holdings Ltd | Other services | 2024 |
| Maybach Roofing & Property Maintenance Ltd | Construction | 2024 |
| Maybury Consultancy Ltd | Administrative & support | 2021 |
| Mayes Estates Limited | Real estate | 1997 |
| Mayes Instruments Limited | Manufacturing | 1993 |
| Mayfair Times Limited | Professional & scientific | 2013 |
| Maygrove Management LLP | | 2021 |
| Mayqin Ltd | Wholesale & retail | 2020 |
| MAZ Electrical and Building Solutions Ltd | Construction | 2024 |
| MC Grammar's Universe Ltd | Information & communication | 2019 |
| Mccann Bainbridge Eddy Limited | Professional & scientific | 1999 |
| Mccloskey Equipment Limited | Wholesale & retail | 2007 |
| Mccloskey Services Limited | Wholesale & retail | 2012 |
| Mcco Limited | Professional & scientific | 1996 |
| MCD Repairs Ltd | Wholesale & retail | 2017 |
| Mcgee Media Limited | Professional & scientific | 2018 |
| Mchr Ltd. | Administrative & support | 2011 |
| Mclean Heritage Holdings Limited | Real estate | 2019 |
| Mcpp Properties Ltd | Real estate | 2020 |
| Mcxi Group Ltd | Professional & scientific | 2024 |
| MDS Sprint Ltd | Transport & logistics | 2025 |
| MDS83 Transport Ltd | Transport & logistics | 2025 |
| ME & Co Ltd | Arts & recreation | 2014 |
| ME Holdings (Property) Limited | Real estate | 2015 |
| MEA Cement Technology Ltd | Professional & scientific | 2023 |
| Meadow & Brook Ltd | Construction | 2020 |
| Meadow View (Charndon) Ltd | Households | 2024 |
| MED Consulting Ltd | Professional & scientific | 2025 |
| Medi-Link International Limited | Administrative & support | 1990 |
| Media Ally Ltd | Professional & scientific | 2014 |
| Media Seven Two Limited | Information & communication | 2011 |
| Medialed Ltd | Manufacturing | 2008 |
| Medical Beauty Skin Ltd | Other services | 2022 |
| Medical Imaging Ascot Ltd | Health & social care | 2019 |
| Medical Services (Immed) UK Ltd | Wholesale & retail | 2011 |
| Medicalsono Ltd | Health & social care | 2023 |
| Medina Care Limited | Professional & scientific | 2024 |
| Medina Dairy Ltd | Wholesale & retail | 2022 |
| Medina Food Services Limited | Wholesale & retail | 2003 |
| Medina Holdings Limited | Professional & scientific | 2003 |
| Medina Property Development Limited | Real estate | 2000 |
| Medina Property Limited | Financial services | 2016 |
| Mega Star Design UK Ltd | Professional & scientific | 2026 |
| Megadesigns Limited | Construction | 2012 |
| Megnatic Consulting Limited | Professional & scientific | 2014 |
| Meidrive Limited | Professional & scientific | 2017 |
| Meldridge Ltd | Information & communication | 2023 |
| Mellori Solutions Ltd | Public administration | 2026 |
| Memlock Limited | Information & communication | 2022 |
| Mentex Health Ltd | Wholesale & retail | 2026 |
| Meow International Limited | Wholesale & retail | 2025 |
| Meraki People Limited | Professional & scientific | 2024 |
| Mercer Planning Consultants UK Limited | Professional & scientific | 2007 |
| Merchant Taylors Place (Croxley) Residents Management Company Limited | Households | 2011 |
| Merchants Court (Chalfont) Management Limited | Households | 2005 |
| Merea Limited | Real estate | 2017 |
| Meridian Management Services Ltd | Professional & scientific | 2026 |