| N P Taylor Payroll Services Limited | Other services | 2015 |
| N Robu Transport Ltd | Transport & logistics | 2019 |
| N&G Capital Ltd | Financial services | 2022 |
| N&N Transport and Services Ltd | Transport & logistics | 2024 |
| N.B.S Holdings Ltd | Financial services | 2011 |
| NAG N1 Construction Ltd | Construction | 2025 |
| Nagsheadlane Limited | Real estate | 2019 |
| Nakarasa Family Properties Ltd | Real estate | 2023 |
| Nalla Patisserie Ltd | Hospitality | 2025 |
| Nanno IT Ltd | Construction | 2017 |
| Nannokhads Ltd | Real estate | 2023 |
| Narrow Minded Railworks Ltd | Manufacturing | 2023 |
| Nasir Holdings Limited | Financial services | 2021 |
| Nassa Flooring Ltd | Construction | 2026 |
| Nathan Waters Ltd | Information & communication | 2010 |
| Nawojnik Ltd | Transport & logistics | 2024 |
| NE Advisory Limited | Professional & scientific | 2018 |
| Needatrade Ltd | Construction | 2019 |
| Neesh Enterprises Ltd | Other services | 2019 |
| Neptumar Agencies Ltd | Transport & logistics | 2015 |
| Nesa Investments Limited | Real estate | 2019 |
| NET Comms Solutions Ltd | Construction | 2017 |
| Netcast Ventures Limited | Professional & scientific | 2011 |
| New Bond Cleaning Services Limited | Administrative & support | 1973 |
| New Enterprise Pest Control (Essex) Ltd | Administrative & support | 2014 |
| New Osmanli Ltd | Hospitality | 2022 |
| Newer DON Ltd | Real estate | 2024 |
| Newsline Essex Ltd | Manufacturing | 1998 |
| Next Steps Learning Ltd | Education | 2026 |
| Neza Building Services Ltd | Construction | 2019 |
| NF Capital Limited | Financial services | 2014 |
| NFT Holdings Ltd | Professional & scientific | 2026 |
| Ngooi & EBA Limited | Education | 2026 |
| Ngooi Badminton Ltd | Education | 2025 |
| NIA Estates Limited | Real estate | 2025 |
| Nicholls Accountants Ltd | Professional & scientific | 2022 |
| Nicholls Corporate Entertainment Ltd | Hospitality | 2024 |
| Nicholls Entertainment Ltd | Arts & recreation | 2022 |
| Nicholls Management Ltd | Financial services | 2024 |
| Nicktrail Ltd | Construction | 2024 |
| Nidom Limited | Information & communication | 1993 |
| Nikelmon Services Limited | Professional & scientific | 2016 |
| Nimbus Test Limited | Professional & scientific | 2025 |
| Nina M Limited | Real estate | 2003 |
| Nitropharma Limited | Professional & scientific | 2026 |
| NKD Beauty Ltd | Other services | 2025 |
| NO78 Ltd | Professional & scientific | 2016 |
| Noblenest Developments Ltd | Real estate | 2025 |
| NOH Services Group Ltd | Construction | 2024 |
| Nomico Electrical Company Limited | Construction | 1973 |
| Nomico Fire & Security Limited | Administrative & support | 2018 |
| Nomico Group Holdings Limited | Financial services | 2026 |
| Nomico Group Limited | Financial services | 2020 |
| Noor Essex Ltd | Construction | 2024 |
| Nora Lucy Bell Private Chef Ltd | Hospitality | 2025 |
| North Group Services Ltd | Professional & scientific | 2025 |
| North Shore Drainage Ltd | Construction | 2022 |
| Northwood Developments Limited | Construction | 2019 |
| Norvex Property Holdings Ltd | Real estate | 2026 |
| Nova Analytica Ltd | Information & communication | 2021 |
| Nova Brows Ltd | Professional & scientific | 2025 |
| NP Smartchoice Ltd. | Construction | 2019 |
| NPC Communications Ltd | Information & communication | 2019 |
| NRB Autos Ltd | Wholesale & retail | 2023 |
| Nslt Services Limited | Professional & scientific | 2011 |
| Nugent Services Ltd | Construction | 2007 |
| Nurses ET AL. Limited | Health & social care | 2021 |
| NZ3 Ltd | Wholesale & retail | 2022 |
| O'Connor Drylining Ltd | Construction | 2020 |
| O. B. Facades Limited | Professional & scientific | 2021 |
| O.B.I Skin Clinic Limited | Health & social care | 2025 |
| Oa&Oa Limited | Energy | 2018 |
| Oaal Limited | Health & social care | 2019 |
| Oak Construction and Project Management Ltd | Construction | 2026 |
| Oak Corp Ltd | Professional & scientific | 2025 |
| Oakfields 21 Ltd | Construction | 2021 |
| Oakley JB Limited | Construction | 2025 |
| Oakmere Contract Services Ltd | Construction | 2012 |
| Oakmere Demolition Ltd | Professional & scientific | 2015 |
| Oakmere Group Limited | Financial services | 2015 |
| Oaks Fashion & Interior Design Ltd | Wholesale & retail | 2025 |
| Oakwood Court (Gidea Park) Management Company Limited | Households | 1986 |
| Oast & Tread Brewing Ltd | Manufacturing | 2019 |
| Obsidere Bona Partners Ltd | Professional & scientific | 2023 |
| OC Investment Management Ltd | Households | 2022 |
| Ocean Gateway (2) LLP | | 2015 |
| Ocean Gateway LLP | | 2009 |
| Ocean Pacific Shipping Line UK Ltd | Transport & logistics | 2023 |
| Ocean Shipping Advisors Limited | Professional & scientific | 2020 |
| Ocpe Limited | Professional & scientific | 2022 |
| ODA Bar and Lounge Limited | Hospitality | 2026 |
| Office Furniture 24/7 Ltd | Wholesale & retail | 2025 |
| Olafek Trading Ltd | Water & waste | 2015 |
| OLY Cristal Limited | Administrative & support | 2026 |
| Omaas Technologies Ltd | Information & communication | 2024 |
| OMC Packaging and Stationery Supplies Ltd | Wholesale & retail | 2008 |
| Omnia Talent Ltd | Arts & recreation | 2020 |
| ON Call Property Services Ltd | Construction | 2015 |
| On-Site Business Systems Limited | Information & communication | 1997 |
| Ondine LLP | | 2025 |