| Masska Ltd | Other services | 2018 |
| Master Access Tower & Tubes Scaffolding Ltd | Construction | 2026 |
| Master Care Ltd | Administrative & support | 2022 |
| Master Henry Ltd | Professional & scientific | 2014 |
| Master Studio Ltd | Administrative & support | 2016 |
| Masterman Park Homes Limited | Real estate | 1994 |
| Masterpiece Innovative Solutions Limited | Professional & scientific | 2013 |
| Masters Gardens Limited | Administrative & support | 2018 |
| Masters Marine Services (Norfolk) Ltd | Administrative & support | 2015 |
| Masters of Norwich Limited | Other services | 2023 |
| Masterseal Limited | Construction | 2002 |
| Matane Sushi Limited | Hospitality | 2018 |
| Match Distribution Ltd | Wholesale & retail | 2025 |
| Matchbox Media Limited | Professional & scientific | 2014 |
| Matchstick Creative Ltd | Professional & scientific | 2018 |
| Matedy Limited | Construction | 2026 |
| Math Ninjas Limited | Education | 2017 |
| Mathsnet Limited | Education | 2011 |
| Matless Maintenance Services Ltd | Manufacturing | 2025 |
| Maton House Ltd | Real estate | 2020 |
| Matrix Construction Solutions Limited | Professional & scientific | 2025 |
| Matrix Hair and Beauty Academy Ltd | Other services | 2020 |
| Mats Mowers Limited | Other services | 2002 |
| Matshed Limited | Real estate | 2010 |
| Matt Adlard Ltd | Information & communication | 2019 |
| Matt Closs Travel Counsellor Ltd | Administrative & support | 2025 |
| Matt Cross Carpentry Ltd | Construction | 2023 |
| Matt Griggs Architects Ltd | Professional & scientific | 2025 |
| Matt Keal Photography Ltd | Professional & scientific | 2013 |
| Matt Nobbs Limited | Arts & recreation | 2026 |
| Matt Preston Property Ltd | Real estate | 2016 |
| Matt Tills Construction Limited | Construction | 2012 |
| Matt Whitehead Ltd | Professional & scientific | 2014 |
| Matteo Property's Ltd | Real estate | 2025 |
| Matter of Fact Retrofit Ltd | Professional & scientific | 2024 |
| Matter of Place Architects CIC | Professional & scientific | 2022 |
| Mattheea Ltd | Transport & logistics | 2016 |
| Matthew David Mayfair 2018 Limited | Other services | 2018 |
| Matthew Farrington Ltd | Construction | 2014 |
| Matthew Healthcare Solutions Ltd | Health & social care | 2026 |
| Matthew Hustler Limited | Agriculture & fishing | 2018 |
| Matthew J Consulting Ltd | Professional & scientific | 2026 |
| Matthew Project Enterprises Limited | Health & social care | 2017 |
| Matthew Webster Autos Ltd | Wholesale & retail | 2022 |
| Matthews Consulting Services Limited | Professional & scientific | 2025 |
| Matthews Law Limited | Extraterritorial | 2011 |
| Mattress Craft Ltd | Wholesale & retail | 2020 |
| Mattress Trader Company (UK) Ltd | Administrative & support | 2019 |
| Mattressman Ltd | Wholesale & retail | 2004 |
| Mattyinkle Ltd | Hospitality | 2020 |
| Mau/Brookes Investments Ltd | Real estate | 2019 |
| Maura Ltd | Wholesale & retail | 2021 |
| Mauree Care Limited | Extraterritorial | 2021 |
| Maureen Carson Health Executive Consultancy Limited | Public administration | 2013 |
| Maurice Varney Ltd | Water & waste | 2010 |
| Mava Medical Limited | Health & social care | 2019 |
| Maverick Engineering Limited | Manufacturing | 2013 |
| Mavi Group Limited | Hospitality | 2026 |
| Mavro Communications Limited | Professional & scientific | 2017 |
| Mavuso Ltd | Health & social care | 2024 |
| MAX Computer Support Limited | Information & communication | 2017 |
| MAX Lexi Ltd | Professional & scientific | 2025 |
| Maxcraft Creations Ltd | Wholesale & retail | 2024 |
| Maxgem Limited | Wholesale & retail | 2023 |
| Maxi L Ltd | Other services | 2019 |
| Maxillo Private Limited | Transport & logistics | 2024 |
| Maxus Parts Direct Limited | Extraterritorial | 2023 |
| Maxwell Pedrosa Ltd | Real estate | 2021 |
| MAY Financial Ltd | Financial services | 2025 |
| MAY Marigold CIC | Professional & scientific | 2025 |
| Maya & Co Property Investments Ltd | Real estate | 2022 |
| Maya Auto Doctor Ltd | Wholesale & retail | 2025 |
| Maya Medical Consultancy Limited | Health & social care | 2010 |
| Maya's Soulcave Ltd | Health & social care | 2023 |
| Mayan Interiors Limited | Construction | 2020 |
| Mayaranis Pranavam School of Dance and Music Ltd | Arts & recreation | 2026 |
| Maybe Industrial UK Limited | Professional & scientific | 2012 |
| Maycraft (Boat Service) Limited | Manufacturing | 1965 |
| Mayday Group Holdings Limited | Financial services | 2018 |
| Mayday Office Equipment Services Holdings Limited | Extraterritorial | 2012 |
| Mayday Office Equipment Services Limited | Wholesale & retail | 1978 |
| Maydun Limited | Health & social care | 2016 |
| Mayeflower Contractors Ltd | Construction | 2025 |
| Mayen Properties Ltd | Real estate | 2024 |
| Mayes and Co (L&P) Ltd | Real estate | 2015 |
| Mayfield Livery Ltd | Agriculture & fishing | 2023 |
| Mayfield Matrix Ltd | Wholesale & retail | 2019 |
| Mayfield Norwich Limited | Wholesale & retail | 2017 |
| Mayflower Corporation Ltd | Education | 2023 |
| Mayhan Properties Limited | Real estate | 2023 |
| Maynard Civil Engineering Recruitment Ltd | Administrative & support | 2002 |
| Maynard Grout Associates Ltd | Construction | 2018 |
| Mayo Marketing Limited | Professional & scientific | 2025 |
| Mays International Group Limited | Wholesale & retail | 2016 |
| Mays International Limited | Wholesale & retail | 2009 |
| Maytek Ltd | Wholesale & retail | 2019 |
| Maze-Advisory Ltd | Professional & scientific | 2026 |
| Mazmednorth Limited | Wholesale & retail | 2014 |
| MB (Norfolk) Ltd | Construction | 2025 |
| MB Cars Norwich Limited | Wholesale & retail | 2017 |