| Michael Alexander Investments Ltd | Real estate | 2019 |
| Mick Bird Associates Ltd | Professional & scientific | 2011 |
| Midas Touch Solutions Limited | Professional & scientific | 2010 |
| Mildmay Road (Romford) Residents Company Limited | Households | 1992 |
| Milivia Hospitality Ltd | Hospitality | 2022 |
| Millett Construction Limited | Construction | 1997 |
| MINER49ER Ltd | Manufacturing | 2017 |
| MINT58 Limited | Hospitality | 2025 |
| Mitre C Ltd | Construction | 2008 |
| Miura Studios Ltd | Professional & scientific | 2009 |
| MJB Decorators Ltd | Construction | 2019 |
| MJH Heating and Plumbing Ltd | Construction | 2022 |
| MKE Logistics Ltd | Transport & logistics | 2026 |
| ML Plumbing & Electrics Ltd | Construction | 2021 |
| MM Domestic Cleaning Limited | Administrative & support | 2018 |
| MNG Studio Ltd | Wholesale & retail | 2014 |
| Moniconn Limited | Real estate | 2021 |
| Monksmore Taverns Ltd | Hospitality | 2025 |
| Montare (Henham) Ltd | Professional & scientific | 2023 |
| Moore & SON Limited | Other services | 2009 |
| Morley Court (Management) Limited | Households | 1996 |
| Morris Farms Limited | Agriculture & fishing | 1947 |
| Mosaic Accountancy Recruitment Limited | Administrative & support | 2015 |
| Mosaic Recruitment Ltd | Administrative & support | 2011 |
| Moss Mentors Ltd | Education | 2021 |
| Moss Properties (Doncaster) Ltd | Real estate | 2006 |
| Moss Properties Lettings Ltd | Real estate | 2021 |
| Moss Properties Sales Ltd | Real estate | 2021 |
| Moss Recruitment Ltd | Administrative & support | 2018 |
| Mountain ASH Construction Consultants Limited | Professional & scientific | 2008 |
| Mountain Removal Courier and Haulage Limited | Transport & logistics | 2018 |
| Mountbatten Court Management Limited | Real estate | 1986 |
| MR Smart Security Ltd | Construction | 2019 |
| Mram Development Ltd | Real estate | 2025 |
| MRC Consultancy Limited | Other services | 2015 |
| MTF Facilities Limited | Professional & scientific | 2012 |
| Much Hadham Investments Ltd | Agriculture & fishing | 2022 |
| Much Hadham Landscapes Limited | Agriculture & fishing | 2002 |
| Mutz Kutz Ltd | Other services | 2017 |
| Mvmrs Limited | Manufacturing | 2004 |
| MW Networking Limited | Information & communication | 2025 |
| My Adventure Travel Company Ltd | Administrative & support | 2022 |
| My Good Salon Limited | Other services | 2019 |
| My Letter From Santa Claus Ltd | Other services | 2011 |
| My View Windows Ltd | Administrative & support | 2021 |
| N H Eaton French Polishers Limited | Other services | 2013 |
| N R S Property Limited | Real estate | 2003 |
| NAS Financial Services Limited | Administrative & support | 2014 |
| National Roofing Solutions Limited | Construction | 2025 |
| Nationwide Vehicle Buyers Limited | Wholesale & retail | 2019 |
| Naturally Attuned Ltd | Health & social care | 2017 |
| NBB Properties Limited | Real estate | 2019 |
| NCF Building Services Ltd | Construction | 2020 |
| Neptune Capital Group Ltd | Administrative & support | 2024 |
| Nevendon Park Management Company Limited | Households | 1993 |
| New ERA Assets Limited | Water & waste | 2012 |
| New ERA Metals Ltd | Water & waste | 2022 |
| New ERA Scrap Ltd | Water & waste | 2014 |
| New Horizon Contract Services Limited | Energy | 2011 |
| New Wave Originals Ltd | Information & communication | 2019 |
| New World Architectural Limited | Professional & scientific | 2010 |
| Newman Property & Boating Limited | Construction | 1999 |
| Newman Property (Group) Limited | Construction | 1999 |
| Newyil Limited | Wholesale & retail | 2010 |
| Nextgen ED SBO LLP | | 2024 |
| Nextwave Experiences Limited | Administrative & support | 2026 |
| Niche ROW Limited | Wholesale & retail | 2025 |
| Nicholson Management Limited | Professional & scientific | 1995 |
| NIK SHA Pro Paint Ltd | Construction | 2022 |
| NO 187 Earlham Grove Management Company Limited | Households | 1960 |
| NO.10 Beauty Limited | Other services | 2017 |
| Noble Dubai Properties Ltd | Real estate | 2024 |
| Norslo Components Limited | Extraterritorial | 1978 |
| Nortonyoung Ltd | Other services | 2012 |
| NP Accounting Services Limited | Professional & scientific | 2008 |
| NPS Services Limited | Construction | 2008 |
| NSP Technologies Ltd | Professional & scientific | 2023 |
| Nubea LLP | | 2026 |
| NUE Derma Clinic Ltd | Health & social care | 2017 |
| NUR Z Properties Ltd | Real estate | 2022 |
| Nvus Trading Ltd | Wholesale & retail | 2017 |
| Oakland Park Woodlands Management Company Limited | Administrative & support | 1984 |
| Oakridge Nursery Limited | Wholesale & retail | 2020 |
| Oaks Lane (Ilford) Management Co. Limited | Hospitality | 1980 |
| Oakwood Media Services Ltd | Professional & scientific | 2022 |
| Oceana Growth Ltd | Transport & logistics | 2019 |
| Octagon Contract Services Limited | Construction | 2003 |
| Octave House Management Company Limited | Households | 2002 |
| Odin Asgard Limited | Administrative & support | 2010 |
| Oeco Facilities Ltd | Administrative & support | 2024 |
| Ogan Interiors Ltd | Construction | 2018 |
| Old Nursery (Shenley) Management Company Limited | Households | 2012 |
| Old Red Lion Theatre PUB Limited | Wholesale & retail | 2012 |
| On-It Power Ltd | Construction | 2026 |
| One Sterling Services (UK) Ltd | Construction | 2016 |
| Online Products & Distribution Ltd | Wholesale & retail | 2025 |
| Opal Corner Limited | Hospitality | 2019 |
| Opal Inns Limited | Hospitality | 2019 |
| Opal Lane Limited | Hospitality | 2019 |
| Opal Peacock Developments Ltd | Construction | 2024 |