| Manor Farm Homes Limited | Real estate | 2017 |
| Manor Farm Livery Stables Limited | Agriculture & fishing | 2006 |
| Manor Farm Rackheath Limited | Agriculture & fishing | 2004 |
| Manor Farm Retreats Ltd | Hospitality | 2021 |
| Manor Farm Stables (Norfolk) Ltd | Agriculture & fishing | 2019 |
| Manor Garage Car Sales Limited | Wholesale & retail | 2023 |
| Manor Lake Ltd | Real estate | 2024 |
| Manor Motorcycles Ltd | Wholesale & retail | 2018 |
| Manor Road 277-323 Freehold Limited | Administrative & support | 2015 |
| Manorfield Cars Limited | Wholesale & retail | 1998 |
| Mansbridge Racing Ltd | Arts & recreation | 2012 |
| Mansbrook,Brosche & Co.Limited | Financial services | 1969 |
| Mansion House Energy Centre Limited | Energy | 2023 |
| Mansion House Hotels Limited | Hospitality | 1973 |
| Manta Innovations Ltd | Information & communication | 2018 |
| Manuel Solutions Limited | Professional & scientific | 2015 |
| Manuel's Limited | Hospitality | 2013 |
| Many Hats Digital Limited | Information & communication | 2017 |
| MAP Strategic Communications Limited | Professional & scientific | 2023 |
| Mapel Studios Ltd | Information & communication | 2024 |
| MAPHO76 Limited | Health & social care | 2023 |
| Maple Building and Developments Limited | Construction | 2019 |
| Maple Carpentry Contractors Limited | Construction | 2016 |
| Maple Leaf Care Norfolk Ltd | Health & social care | 2026 |
| Maple Leaf Montessori Limited | Education | 2015 |
| Mapleleaf Cleaners Limited | Administrative & support | 2000 |
| Maples Grace Ventures Ltd | Real estate | 2025 |
| Maps and Pathways Limited | Information & communication | 2024 |
| Maps Properties Limited | Other services | 1998 |
| Maps Properties Trading Ltd | Administrative & support | 2021 |
| MAR Vehicle Solutions Ltd | Wholesale & retail | 2020 |
| Mara Enterprises Ltd | Real estate | 2023 |
| Maragi Investments Ltd | Financial services | 2025 |
| Marathon Enterprises Limited | Real estate | 1994 |
| Marberton Limited | Wholesale & retail | 2019 |
| Marburdel Ltd | Real estate | 2022 |
| Marc Lewis Design Limited | Arts & recreation | 2020 |
| Marc Moncrieff Limited | Health & social care | 2012 |
| Marcel Delivery Ltd | Transport & logistics | 2019 |
| March Property (Norfolk) Limited | Real estate | 2023 |
| March Vision Limited | Administrative & support | 2025 |
| Marchaunts RTM Company Limited | Households | 2021 |
| Marches Leisure (Ipswich) Limited | Arts & recreation | 2020 |
| Marches Leisure Services (Riverhills) Ltd | Real estate | 2023 |
| Marches Leisure Services Limited | Arts & recreation | 2017 |
| Marcu Calandea Real Estate Ltd | Real estate | 2025 |
| Marcus Hemsley Ltd | Professional & scientific | 2025 |
| Marcus Pearcey Investments Limited | Financial services | 2025 |
| Marcus Tunmore Limited | Construction | 2025 |
| Marcuson Limited | Administrative & support | 2009 |
| Mardent Limited | Health & social care | 2024 |
| Mardle Barn Limited | Wholesale & retail | 2026 |
| Mardle Works Ltd | Professional & scientific | 2026 |
| Marecon Ltd. | Transport & logistics | 1997 |
| Marfan Limited | Administrative & support | 2011 |
| Margaret Emms Ltd | Arts & recreation | 2014 |
| Margaret Howard Theatre Schools Limited | Arts & recreation | 1998 |
| Margaret's Tea & Play Ltd | Wholesale & retail | 2006 |
| Margay Ltd | Professional & scientific | 2022 |
| Marginson Contract Consultancy Services Limited | Professional & scientific | 2009 |
| Marideea Convenience Store Limited | Wholesale & retail | 2018 |
| Marident Ltd | Health & social care | 2026 |
| Mariflex Global Marine Services Limited | Administrative & support | 2024 |
| Marin Partners Limited | Professional & scientific | 2025 |
| Marina GOS Limited | Real estate | 2021 |
| Marine and Subsea Ltd | Construction | 2020 |
| Marine Fabrication U.K Ltd. | Manufacturing | 2017 |
| Marine Park Business Centre Limited | Real estate | 2026 |
| Marine Perfection (SE) Ltd | Manufacturing | 2024 |
| Marine Power Limited | Professional & scientific | 2011 |
| Marine Science Support Ltd | Professional & scientific | 2011 |
| Marine Towers Management Company Limited | Real estate | 2002 |
| Mariners Properties Ltd | Real estate | 2023 |
| Mario Garage Norwich Ltd | Wholesale & retail | 2023 |
| Marios Pizza Takeaway Limited | Hospitality | 2017 |
| Marisco CDC Ltd | Health & social care | 2024 |
| Maritz & Co. Growth Consultancy Ltd | Professional & scientific | 2026 |
| Mariusmotosca Ltd | Transport & logistics | 2017 |
| Marj Property Ltd | Real estate | 2022 |
| Mark a Ashley Limited | Professional & scientific | 2016 |
| Mark Alexander Webster Ltd | Extraterritorial | 2024 |
| Mark Andrew Garden Services Ltd | Extraterritorial | 2025 |
| Mark Blunsten Hair Ltd | Other services | 2017 |
| Mark Dean (U.K.) Limited | Manufacturing | 2003 |
| Mark Fisher Consultancy Ltd | Professional & scientific | 2023 |
| Mark Fitzsimmons Associates Limited | Construction | 2009 |
| Mark Gibbs Real Estate Ltd | Real estate | 2026 |
| Mark Griffin Limited | Professional & scientific | 2015 |
| Mark Hall Constructions Ltd | Construction | 2016 |
| Mark Harvey Masterclass Limited | Professional & scientific | 2025 |
| Mark Harvey Photography Ltd. | Arts & recreation | 2011 |
| Mark Hillier Limited | Real estate | 2012 |
| Mark IT Done Consultants Ltd | Information & communication | 2018 |
| Mark King Property Solutions Ltd | Construction | 2021 |
| Mark Lesley Limited | Wholesale & retail | 2006 |
| Mark Raymond Tiling & Bathrooms Ltd | Construction | 2025 |
| Mark Tremelling Ltd | Health & social care | 2019 |
| Marka Building & Design Ltd | Construction | 2024 |
| Markant Trading Ltd | Transport & logistics | 2011 |
| Market Capital Ltd | Professional & scientific | 2019 |