| Moltke UK Ltd | Manufacturing | 2025 |
| Monro White Hilton Limited | Professional & scientific | 1983 |
| Monster Dog Sports Limited | Other services | 2025 |
| Monty's Walden Ltd | Hospitality | 2024 |
| Moonlight Assets Ltd | Real estate | 2024 |
| Moore Weston Accountants Limited | Professional & scientific | 2005 |
| Moreno Marketing Ltd | Professional & scientific | 2012 |
| Moreno OMH Ltd | Professional & scientific | 2022 |
| Morpheus Investigations Limited | Administrative & support | 2020 |
| Morris House Properties Limited | Real estate | 2018 |
| Mortgage & Money Management Limited | Administrative & support | 2006 |
| Mortimergreen Limited | Information & communication | 2019 |
| Moss & Bird Limited | Real estate | 1998 |
| Motorcycle World Limited Liability Partnership | | 2007 |
| Move United CIC | Arts & recreation | 2026 |
| Moveman Limited | Information & communication | 2003 |
| Mowbray Yard Limited | Households | 2014 |
| MP Paediatric Physio Limited | Health & social care | 2018 |
| MPO Investments Ltd | Administrative & support | 2023 |
| MPR Management Company Limited | Households | 2004 |
| MR Barbers Witham Ltd | Other services | 2021 |
| MR BEN Walker Ltd | Transport & logistics | 2023 |
| MR. Barbers Halstead Ltd | Other services | 2022 |
| MR. Barbers Sawbridgeworth Limited | Other services | 2025 |
| MR. Barbers Welwyn Limited | Other services | 2024 |
| MRD London Ltd. | Administrative & support | 2008 |
| MRM Learning and Development Ltd | Professional & scientific | 2018 |
| MRT Accountants Limited | Professional & scientific | 2023 |
| MSJ Mechanical Services Limited | Construction | 2023 |
| MTC Consultancy Limited | Information & communication | 2012 |
| Mulberry Barns (Management) Co Ltd | Households | 2024 |
| Mulberry House Farms LLP | | 2014 |
| Mulberry House Press Limited | Information & communication | 2011 |
| Multiadaptor Limited | Administrative & support | 2009 |
| Munstead Heath Limited | Administrative & support | 2022 |
| Murdoch Planning Ltd | Professional & scientific | 2013 |
| Murray Wealth Financial Planners LLP | | 2017 |
| Musarum Limited | Agriculture & fishing | 2022 |
| Music Brands Ltd | Professional & scientific | 2018 |
| Music Village Ltd | Arts & recreation | 2003 |
| Must BE Scene Limited | Construction | 2010 |
| My Montessori Hub Ltd | Education | 2025 |
| Myrentedhome Limited | Real estate | 2018 |
| Mysearch Ltd | Administrative & support | 2012 |
| Myspace Garden Studios Ltd. | Construction | 2011 |
| Mysterium Press Limited | Information & communication | 2022 |
| Mystery Bounty Poker Calculator Ltd | Information & communication | 2023 |
| N Gauge Society Limited | Other services | 2018 |
| Nacam Entertainment Limited | Professional & scientific | 2014 |
| NAF Creative Limited | Extraterritorial | 2014 |
| Nagook Limited | Wholesale & retail | 2006 |
| Nail Lounge (Saffron Walden) Ltd | Other services | 2015 |
| Nailey Hall END Management Company Limited | Real estate | 2024 |
| Naked Equine Ltd | Other services | 2023 |
| Naked Science Limited | Manufacturing | 2008 |
| NAM Property Holdings Limited | Real estate | 2024 |
| Nanny Louenna Limited | Health & social care | 2019 |
| Napier Advisors Limited | Health & social care | 2023 |
| Napier P.B LLP | | 2024 |
| National Council for the Training of Journalists | Education | 1992 |
| Navigate Consulting Ltd. | Other services | 2007 |
| Naylor-Barker Limited | Real estate | 2026 |
| Nazeing Golf Club Limited | Real estate | 1990 |
| Nce-Discovery Limited | Professional & scientific | 2001 |
| Nctj Training Limited | Other services | 1994 |
| Nd.Norton Ltd | Construction | 2025 |
| Ndp-Copier and Print Services Ltd | Administrative & support | 2026 |
| Neighked Ltd | Wholesale & retail | 2022 |
| Neil Roper Ltd | Wholesale & retail | 2002 |
| Neil Wicks Plumbing and Heating Limited | Construction | 2016 |
| Nelcol Developments Limited | Construction | 2012 |
| Neoancients Limited | Arts & recreation | 2025 |
| Neon Brand Communications Ltd | Professional & scientific | 2016 |
| Neon LEO Ltd | Wholesale & retail | 2023 |
| Netx Limited | Information & communication | 1996 |
| New Cambridge Tent Company Ltd | Hospitality | 2023 |
| New London Corporation Limited | Administrative & support | 2014 |
| New RAY Enterprises Ltd | Health & social care | 2015 |
| New Standard Hospitality Ltd | Manufacturing | 2026 |
| New Waves CBT Ltd | Health & social care | 2022 |
| Neways Construction Limited | Construction | 2022 |
| Newdales LLP | | 2002 |
| Newport Stores (Essex) Limited | Wholesale & retail | 2008 |
| Newport Youth Club CIC | Arts & recreation | 2021 |
| Newstonegate Ltd | Construction | 2024 |
| Newway Consultancy Limited | Real estate | 2012 |
| Nexus AMC Ltd | Financial services | 2026 |
| Nexus Communications Ltd | Information & communication | 2026 |
| Nexus Group Services Ltd | Administrative & support | 2026 |
| Nexus Lounge (2729) Ltd | Hospitality | 2026 |
| Nexus Lounge Ltd | Hospitality | 2025 |
| NIA Software Consultants Ltd. | Information & communication | 2017 |
| Nick Johnson Painters and Decorators Limited | Construction | 2003 |
| Nightstarleaf Ltd | Manufacturing | 2022 |
| Nigri Consulting Ltd | Administrative & support | 2020 |
| Nimbus Roof Technologies Ltd | Wholesale & retail | 2024 |
| Nimrod Life Sciences Limited | Professional & scientific | 1990 |
| Nine Columns London Ltd | Real estate | 2023 |
| Nine Tries Ltd | Arts & recreation | 2024 |
| Nineninesix Solutions Limited | Information & communication | 2019 |