| Mourelle Designs Limited | Arts & recreation | 2018 |
| Moziga Limited | Real estate | 2015 |
| MP Plaster Works Limited | Construction | 2019 |
| MR Enzo Fish and Chips Ltd | Hospitality | 2025 |
| MR Spice Essex Ltd | Hospitality | 2024 |
| MSB Masonry Ltd | Manufacturing | 2013 |
| Msec Systems Ltd | Construction | 2024 |
| MTG Trading Limited | Manufacturing | 2015 |
| Muck Away Bees Ltd | Other services | 2025 |
| Mulberry Place Parking Limited | Administrative & support | 2011 |
| Mumford Engineering Ltd | Manufacturing | 2013 |
| Munchie X Limited | Hospitality | 2026 |
| Murray & Clyde Associates Ltd | Professional & scientific | 2020 |
| Museum View Freehold Ltd | Households | 2018 |
| Mviro Limited | Water & waste | 2022 |
| MVS Consultancy Ltd | Professional & scientific | 2014 |
| MVS Properties Ltd | Hospitality | 2010 |
| MWP Services Ltd | Real estate | 2020 |
| My Intelligent Assistant Ltd | Information & communication | 2026 |
| My Smile Ltd | Health & social care | 2024 |
| Mykard Ltd | Construction | 2023 |
| Mystical Shine Ltd | Administrative & support | 2017 |
| N C C (Essex) Limited | Construction | 2000 |
| N-Tyce Nails & Beauty Ltd | Other services | 2013 |
| Nacho HUT Ltd | Hospitality | 2025 |
| Naco Connections Limited | Financial services | 2024 |
| NAD Solution Ltd | Construction | 2025 |
| Naglotech Ltd | Information & communication | 2005 |
| Nalma Studio Ltd | Other services | 2026 |
| Nambridge Ltd | Extraterritorial | 2012 |
| NAN Renovations Ltd | Real estate | 2024 |
| Nats Nursery Ltd | Education | 2013 |
| Nava Supermarket Ltd | Wholesale & retail | 2024 |
| Navita Group Ltd | Administrative & support | 2019 |
| Ndms Properties Ltd | Real estate | 2016 |
| Ndwt Ltd | Hospitality | 2025 |
| Neilson Baxter Limited | Hospitality | 2018 |
| Nelson Innovation Limited | Manufacturing | 2026 |
| Neon Forrest Technologies Ltd | Information & communication | 2025 |
| Never SAY DIE Records Ltd | Information & communication | 2009 |
| Neville & Neville Consultancy Ltd | Professional & scientific | 2024 |
| New Dawn Property Ltd | Real estate | 2025 |
| Newman Investments Limited | Financial services | 2021 |
| Next GEN Building Supplies Ltd | Wholesale & retail | 2025 |
| Nia-Kika Limited | Public administration | 2019 |
| Nikki’S Catering Ltd | Hospitality | 2024 |
| Nimmo's of Clacton Limited | Financial services | 1965 |
| Nino SAI Limited | Professional & scientific | 2017 |
| Niranfajo Limited | Professional & scientific | 2025 |
| NMW Franchise Services Limited | Professional & scientific | 2011 |
| NO 61-67 Upton Park Management Limited | Households | 1998 |
| Noaa Group Ltd | Hospitality | 2025 |
| Noble Care Plus Ltd | Health & social care | 2025 |
| Nolan Recruitment Limited | Administrative & support | 2025 |
| Northdown Commercial Development Ltd | Professional & scientific | 2018 |
| NRG Electrical Contractor (Tendring) Limited | Construction | 2022 |
| NS Data Ltd | Construction | 2025 |
| Nu-Wey Properties Limited | Real estate | 2025 |
| Nucleoedit Ltd | Professional & scientific | 2025 |
| Nysko Games Ltd. | Information & communication | 2017 |
| O & D Developments Ltd | Construction | 2021 |
| O'Brien Builders Ltd | Construction | 2025 |
| O'Brien Maintenance Ltd | Administrative & support | 2025 |
| O'Brien Property Management Ltd | Administrative & support | 2022 |
| Oak Properties Essex Limited | Real estate | 2026 |
| Oak Tree Life Skills CIC | Education | 2023 |
| Oak View Gardens Management Company Limited | Households | 2018 |
| Oakcrest Construction Ltd | Construction | 2025 |
| Oakleigh Residential Park Limited | Construction | 2016 |
| Oakleigh Sales Limited | Real estate | 2019 |
| Oakley Designworks Ltd | Professional & scientific | 2017 |
| OB Architectural Design Ltd | Professional & scientific | 2022 |
| Oc&V Construction Limited | Construction | 2025 |
| Ocean Edge Limited | Administrative & support | 2024 |
| OH My Graze Ltd | Hospitality | 2020 |
| OH Sugar Ltd | Wholesale & retail | 2013 |
| Okans Global Energy Limited | Mining & quarrying | 2019 |
| Old Road Auto Sales Ltd | Wholesale & retail | 2025 |
| Old Road Barbers Ltd | Other services | 2026 |
| Old Road Minimarket Ltd | Wholesale & retail | 2026 |
| Oliver Family Holdings Ltd | Real estate | 2024 |
| Oliver Hoult Homes Ltd | Construction | 2025 |
| Olivers Autos Ltd | Wholesale & retail | 2021 |
| Olivmed Group Limited | Financial services | 2025 |
| Olliz Dents Ltd | Wholesale & retail | 2026 |
| ON Site Caravan Sales Ltd | Hospitality | 2023 |
| On-The-Go Eats Limited | Hospitality | 2025 |
| Opsshaper Ltd. | Administrative & support | 2018 |
| Optimal Endurance Coaching Ltd | Information & communication | 2022 |
| ORI Apera Limited | Other services | 2025 |
| Origin Talent Ltd | Arts & recreation | 2024 |
| Otterco Ltd | Administrative & support | 2025 |
| Oulai Corporation Group ( OCG) Limited | Manufacturing | 2018 |
| Outline Media Productions Ltd | Professional & scientific | 2021 |
| Outshine Design Limited | Other services | 2008 |
| Owlbut's School of the Air Ltd | Information & communication | 2023 |
| Owlbut's World of Learning Ltd | Information & communication | 2014 |
| P & D Maddison Limited | Real estate | 2018 |
| P & N Driver Hire Ltd | Transport & logistics | 2015 |
| P Mountford Holdings Ltd | Administrative & support | 2023 |