| Motosas Ltd | Wholesale & retail | 2025 |
| Mount END Barns Limited | Households | 2025 |
| Moving House (UK) Limited | Administrative & support | 2004 |
| Moxon Services Limited | Education | 2018 |
| Mrmr Ltd | Information & communication | 2026 |
| MSC Group Ltd | Financial services | 2019 |
| MSI Interiors Limited | Construction | 2015 |
| Mspp Preconstruction & Procurement Specialists LLP | | 2026 |
| MU Presentation Ltd | Financial services | 2022 |
| Multi Building Construction Ltd | Administrative & support | 2016 |
| Multi Floors (2025) Ltd | Construction | 2025 |
| Muscle Gym Ltd | Wholesale & retail | 2019 |
| Music Making Sense | Education | 2017 |
| Must Go Limited | Wholesale & retail | 2026 |
| My Sport Photos Ltd. | Professional & scientific | 2023 |
| My Vote Advisor Limited | Professional & scientific | 2009 |
| MY55 Properties Limited | Real estate | 2025 |
| Nabi Qasim Ltd | Manufacturing | 2023 |
| Nail Stories 80 Ltd | Other services | 2025 |
| Narrative Social Work Solutions Ltd | Health & social care | 2022 |
| NAS Property (U.K.) Ltd | Real estate | 2020 |
| NBK Residential Limited | Real estate | 2026 |
| Neil Dawson Art Limited | Arts & recreation | 2008 |
| Neill & Co (Theydon) Limited | Professional & scientific | 2005 |
| Neill Wright and Associates Limited | Professional & scientific | 2020 |
| Neon Consultants Ltd | Professional & scientific | 2024 |
| Nerin Limited | Hospitality | 2024 |
| Nesby Medical Services Limited | Other services | 2016 |
| NET TEN Electrical Ltd | Construction | 2018 |
| New Horizons Academia Limited | Administrative & support | 2023 |
| New Life Construction Ltd | Construction | 2020 |
| New Star Holdings Ltd | Real estate | 2021 |
| New Technology Ltd | Wholesale & retail | 2025 |
| Newfound Living Limited | Information & communication | 2019 |
| Newslitter Limited | Manufacturing | 1980 |
| NEXA360 LLP | | 2023 |
| Nexgen Developers & Management Limited | Construction | 2025 |
| Next GEN Trade Academy Ltd | Education | 2025 |
| Nextflow Logistics Ltd | Transport & logistics | 2025 |
| Nextgen Southend Commercial Limited | Construction | 2024 |
| Nice Gateway Limited | Information & communication | 2025 |
| Nichols Bros (Wood Turners) Limited | Manufacturing | 1961 |
| Nick Rayment Ltd | Financial services | 2014 |
| Nickel Solutions Ltd | Wholesale & retail | 2016 |
| Nicol & Sons Limited | Financial services | 2017 |
| Nightingale Disabled Transport Limited | Transport & logistics | 2006 |
| Nini G Properties Ltd | Real estate | 2025 |
| Nixcom Limited | Information & communication | 2019 |
| NMA Essex Ltd | Health & social care | 2025 |
| NMC (Essex) Ltd | Wholesale & retail | 2025 |
| Noknotco Limited | Wholesale & retail | 2020 |
| Norseman Consultancy Limited | Professional & scientific | 2021 |
| North Weald Barbers Ltd | Other services | 2019 |
| North Weald Flight Training Limited | Education | 2014 |
| North Weald Motorcycles Ltd | Wholesale & retail | 2012 |
| Northcote and Sons Ltd | Transport & logistics | 2020 |
| Notley Property Ltd | Real estate | 2023 |
| Nsquared Consulting Limited | Information & communication | 2007 |
| Ntj-Group Limited | Construction | 2018 |
| Nuky Ltd | Construction | 2020 |
| Number 12 Education Marketing Ltd | Professional & scientific | 2012 |
| Nurturing Solutions Limited | Information & communication | 2023 |
| Nutrihome Ltd | Wholesale & retail | 2024 |
| Nuvotech Limited | Information & communication | 1999 |
| O.B.Build Contractors Ltd | Construction | 2016 |
| OCF Property Ltd | Real estate | 2025 |
| Oeco UK Ltd | Construction | 2025 |
| OFF Market Real Estate Ltd | Real estate | 2017 |
| OH Scaffolding Ltd | Construction | 2022 |
| Ol.Limitless Limited | Other services | 2002 |
| Olarrian Solutions Ltd | Information & communication | 2017 |
| Olde English Contracts Limited | Administrative & support | 2015 |
| ON Air Production Services Ltd | Information & communication | 2012 |
| One America Square Limited | Real estate | 2026 |
| One America Square LL Limited | Real estate | 2026 |
| Ongar Dairy Limited | Wholesale & retail | 2017 |
| Online Fashion Ventures Ltd | Wholesale & retail | 2024 |
| Onsite Hospitality Limited | Hospitality | 2018 |
| Open Box Education Centre Limited | Education | 2017 |
| Opinari Limited | Mining & quarrying | 2004 |
| Opulent Structures Limited | Construction | 2024 |
| Orclans Property Ltd | Real estate | 2024 |
| Ordatus Ltd | Information & communication | 2016 |
| Organic Resources Limited | Wholesale & retail | 2025 |
| Orion Heating & Renewables Limited | Wholesale & retail | 2012 |
| Oscom Supplies Limited | Wholesale & retail | 2026 |
| OSD Asset Management Ltd | Administrative & support | 2024 |
| Osteo Limited | Other services | 2002 |
| OUD Jannah Ltd | Wholesale & retail | 2025 |
| Oudeliq Parfums Limited | Wholesale & retail | 2025 |
| OUR FD Limited | Professional & scientific | 2013 |
| Outside in Property Services UK Ltd | Construction | 2026 |
| Owen Massarella Mortgages Ltd | Professional & scientific | 2026 |
| P & M Systems Ltd | Information & communication | 2014 |
| P & WD Limited | Construction | 2019 |
| P H Building Maintenance Limited | Construction | 2002 |
| P&N Consulting Ltd | Professional & scientific | 2019 |
| P2 Projects Limited | Information & communication | 2012 |
| Padfield (Brownings) Limited | Agriculture & fishing | 1977 |
| Pakthat Ltd | Administrative & support | 2011 |