| MTC Security Trustee Limited | Financial services | 2015 |
| Mtce Limited | Manufacturing | 1992 |
| MTD Clothing Ltd | Water & waste | 2022 |
| MTE FX Limited | Financial services | 2025 |
| Mtechnicuk Ltd | Wholesale & retail | 2024 |
| Mtelis Limited | Information & communication | 2001 |
| MTL Homes Limited | Construction | 2022 |
| MTM Retail Ltd | Wholesale & retail | 2024 |
| Mtn-I Limited | Information & communication | 2000 |
| Mtpfl Ltd | Information & communication | 2020 |
| MTR Building Services Ltd | Construction | 2021 |
| Mtrakag Ltd | Information & communication | 2026 |
| MTW Speech and Language Therapy LLP | | 2018 |
| MU Vape Limited | Wholesale & retail | 2020 |
| Muchross Limited | Wholesale & retail | 1979 |
| Muchuo's Centre for Training and Development Ltd | Education | 2025 |
| Muckifoot Studios Limited | Information & communication | 2025 |
| MUD Hub CIC | Education | 2025 |
| MUD Orange Ltd | Professional & scientific | 2019 |
| Mudbrick Properties Ltd | Real estate | 2016 |
| Mugwise Ltd | Wholesale & retail | 2020 |
| Muhammad Deals Ltd | Wholesale & retail | 2025 |
| Muir Associates (UK) Limited | Professional & scientific | 1994 |
| Mulbarton Dental Practice Limited | Health & social care | 2012 |
| Mulbarton M.O.T & Repair Centre Limited | Wholesale & retail | 2022 |
| Mulbarton Sports and Social C.I.C. | Hospitality | 2025 |
| Mulbarton Wanderers C.I.C. | Education | 2023 |
| Mulbarton Windows Ltd | Construction | 2020 |
| Mulberries and the Messiah Ltd. | Information & communication | 2025 |
| Mulberry Court (Taverham) Management Company Limited | Households | 1994 |
| Mulberry Court 36-39 RTM Company Limited | Real estate | 2009 |
| Mulberry Court 51-54 RTM Company Limited | Real estate | 2011 |
| Mulberry Court 60-63 RTM Company Limited | Households | 2010 |
| Mulberry House Sctv Holdings Limited | Financial services | 2020 |
| Mulberry Jack Limited | Manufacturing | 2020 |
| Mulberry Tree Lettings Limited | Real estate | 2023 |
| Mule Industry Limited | Administrative & support | 2005 |
| Mulholland Watch Club Limited | Wholesale & retail | 2026 |
| Multi Catering Technologies Ltd | Professional & scientific | 2013 |
| Multi Project Plus Ltd | Manufacturing | 2025 |
| Multi Trade Services Ltd | Construction | 2015 |
| Multiden Limited | Wholesale & retail | 2019 |
| Multifast UK Limited | Wholesale & retail | 1995 |
| Multimatic Holdings Limited | Extraterritorial | 1996 |
| Multimatic Ltd. | Manufacturing | 1996 |
| Multimatic U.K. Limited | Manufacturing | 1994 |
| Multimedia Technologies Ltd | Wholesale & retail | 2017 |
| Multimedic Limited | Financial services | 2022 |
| Multioptics Limited | Manufacturing | 2016 |
| Multiplex Hub PVT Ltd | Wholesale & retail | 2025 |
| Multishape Metalcraft Limited | Manufacturing | 1994 |
| Multivalue Systems Ltd | Administrative & support | 2020 |
| MUM DEM CIC | Health & social care | 2024 |
| Mumbai Kitchen Norwich Ltd | Hospitality | 2022 |
| Mumix Properties Ltd | Real estate | 2015 |
| MUNACHI90 Limited | Health & social care | 2018 |
| Muncheese WM Ltd | Hospitality | 2020 |
| Munday Builders Limited | Construction | 2005 |
| Munday Roundhouse Developments Ltd | Construction | 2023 |
| Munday Roundhouse Land Developments Ltd | Construction | 2023 |
| Mundesley Beck Limited | Households | 2017 |
| Mundesley Golf Club Limited | Arts & recreation | 1901 |
| Mundesley Holiday Village Limited | Hospitality | 2014 |
| Mundesley Medical Services Limited | Health & social care | 2001 |
| Mundesley Properties Limited | Real estate | 1947 |
| Mundham Estates LLP | | 2012 |
| Mundham Land Limited | Construction | 2019 |
| Munichworxs Limited | Wholesale & retail | 2015 |
| Munro's Restaurant Limited | Hospitality | 2014 |
| Munster & Broad Limited | Information & communication | 2018 |
| Muntjac Hospitality Ltd | Professional & scientific | 2026 |
| Muralise LLP | | 2026 |
| Murdoch Optical Ltd | Health & social care | 2002 |
| Murganos Limited | Wholesale & retail | 2015 |
| Murla Media Ltd | Professional & scientific | 2025 |
| Murphy Consult Limited | Professional & scientific | 2025 |
| Murphy Physiotherapy Limited | Health & social care | 2006 |
| Musa Caterers Ltd | Hospitality | 2023 |
| Musaddaq & Co Limited | Manufacturing | 2019 |
| Musata Kebabs Ltd | Hospitality | 2024 |
| Muse Hair and Beauty Studio Ltd | Real estate | 2025 |
| Museum of Street Art Ltd | Wholesale & retail | 2022 |
| Mushroomery Ltd | Agriculture & fishing | 2026 |
| Mushys Fish Bar Ltd | Hospitality | 2018 |
| Music Worldwide Limited | Education | 2004 |
| Musicing Ltd | Education | 2026 |
| Musictakeaway Limited | Wholesale & retail | 2003 |
| Mussett Marine Limited | Manufacturing | 2019 |
| Mussett Racing Limited | Manufacturing | 2012 |
| Must Have Tickets Ltd | Wholesale & retail | 2022 |
| Mustard Limited | Information & communication | 1980 |
| Muswell Hill Road Management Company Limited | Households | 2025 |
| Mutambara PVT Ltd | Transport & logistics | 2026 |
| Muteuro Limited | Health & social care | 2014 |
| MV Supply UK Limited | Construction | 2024 |
| MVH Management Limited | Construction | 2012 |
| Mvpea Limited | Manufacturing | 2022 |
| MW & Co Properties Limited | Real estate | 2023 |
| MW Groundworks (Norfolk) Ltd | Construction | 2019 |
| MW Holdings (Norfolk) Ltd | Professional & scientific | 2019 |