| New Life Business Consultants Limited | Financial services | 2007 |
| New Seasons Consulting Limited | Administrative & support | 2022 |
| New World Marine Insurance Consultants Limited | Financial services | 2001 |
| Nexchoice Ltd | Real estate | 2024 |
| Nexgen Packaging, UK, Limited | Manufacturing | 2013 |
| Nexus Infrastructure PLC | Construction | 2005 |
| Nexus Park Limited | Construction | 2019 |
| NF Consultants Limited | Professional & scientific | 2012 |
| NGC Pubs Ltd | Hospitality | 2018 |
| NGD Productions Ltd. | Education | 2016 |
| Nicholls Bros.Limited | Real estate | 1954 |
| Nicie’S Nest Limited | Administrative & support | 2021 |
| Nicks Jewellery Essex Ltd | Wholesale & retail | 2021 |
| Niconpri Examinations Consultancy Ltd | Other services | 2022 |
| Nijjar Investments Ltd | Real estate | 2022 |
| Nikcre Limited | Wholesale & retail | 2015 |
| Nilo & Company T/A Shalford Village Stores Limited | Wholesale & retail | 2015 |
| Nine Fires Limited | Wholesale & retail | 2022 |
| Nine Step Media Limited | Professional & scientific | 2013 |
| Nirvana Digital Ltd | Professional & scientific | 2015 |
| Nirvana Marine UK Limited | Manufacturing | 2026 |
| Nishikoi Aquaculture Limited | Manufacturing | 1991 |
| NIX Palmer Limited | Professional & scientific | 2020 |
| NJK Office Ltd | Administrative & support | 2022 |
| Njrix Services Ltd | Transport & logistics | 2025 |
| NJT Carpentry Services Ltd | Manufacturing | 2023 |
| Njtc Limited | Professional & scientific | 2011 |
| NM Specialist Transport Ltd | Administrative & support | 2016 |
| Nnenisco Care Company Limited | Health & social care | 2022 |
| Nobale Construction Ltd | Construction | 2023 |
| Noble and Associates Ltd | Administrative & support | 2009 |
| Noctura Creative Ltd | Extraterritorial | 2017 |
| NODE2NODE.INVESTMENTS Ltd | Financial services | 2025 |
| Nodeable Limited | Information & communication | 2015 |
| Noel House Surgery Ltd | Health & social care | 2025 |
| Nogoalsbarred Fitness Limited | Arts & recreation | 2021 |
| Noir Glow Ltd | Other services | 2025 |
| Noir Tanning Ltd | Other services | 2025 |
| Nomadic Spaces Limited | Administrative & support | 2008 |
| Nook Property Ltd | Real estate | 2015 |
| Noorcare Services Ltd Ltd | Health & social care | 2025 |
| Norfolk Consultancy Services Ltd | Administrative & support | 2014 |
| Normtech Ltd | Information & communication | 2026 |
| North Essex Farm Cluster CIC | Agriculture & fishing | 2023 |
| North Island Lodge Ltd | Hospitality | 2024 |
| Northey Point Limited | Professional & scientific | 2018 |
| Northrom Investments Limited | Financial services | 1978 |
| Nortown Food Ltd | Hospitality | 2024 |
| Nortown Property Ltd | Real estate | 2024 |
| Notley Health Ltd | Financial services | 2023 |
| Notley Lodge Management Company Limited | Households | 1993 |
| Nougienous Ltd | Wholesale & retail | 2025 |
| Nova Office Ltd | Wholesale & retail | 2025 |
| Novadata Tachograph Analysis Bureau Limited | Education | 1993 |
| Nowakiwskyj Fit Ltd | Arts & recreation | 2025 |
| Nrs-Eu Limited | Wholesale & retail | 2025 |
| Nrs-Uk Limited | Wholesale & retail | 2025 |
| Ntsgroup Ltd | Wholesale & retail | 2025 |
| Nuovo Catalyst Consulting Ltd | Professional & scientific | 2025 |
| Nuovo Clinic Ltd. | Administrative & support | 2020 |
| Nursery Cafe Ltd | Hospitality | 2019 |
| Nutritional Performance Partners Limited | Professional & scientific | 2025 |
| NV Homes Limited | Real estate | 2025 |
| NXT Level Live Ltd | Administrative & support | 2025 |
| Nxuspay Ltd | Information & communication | 2025 |
| O B Catering Jollof Delights Ltd | Hospitality | 2025 |
| O T Dare Joinery Consultants Ltd | Professional & scientific | 2018 |
| O&U Property Services Ltd | Construction | 2024 |
| Oak Developments (Chapel Hill) Limited | Real estate | 2018 |
| Oak Developments (Lakes Road) Limited | Construction | 2004 |
| Oak Estates (Essex) Limited | Real estate | 2010 |
| Oakdale Securities Ltd | Construction | 2016 |
| Oakfield Financial Services Limited | Financial services | 2003 |
| Oakland Bespoke Conservatories Windows and Doors Limited | Construction | 2006 |
| Oakland Domestic Electrical Services Limited | Construction | 2022 |
| Oakland Kitchens Bedrooms and Bathrooms Limited | Construction | 2006 |
| Oakland Orangeries Limited | Construction | 2010 |
| Oaklands (Copford) Estate Management Company Limited | Real estate | 2024 |
| Oaklands Park Management Company Limited | Households | 1985 |
| Oakmarsh Ltd | Other services | 2024 |
| OC Media Solutions Limited | Other services | 2020 |
| Occhealth Direct Ltd | Health & social care | 2019 |
| OD Commerce Limited | Wholesale & retail | 2024 |
| OFF the Beaten Track Ltd | Hospitality | 2018 |
| Offerformal Property Management Limited | Households | 1994 |
| Ogpadel Ltd | Wholesale & retail | 2024 |
| Ogwen Ltd | Professional & scientific | 2023 |
| OHL Contractors Ltd | Construction | 2016 |
| Ojay Property Solutions Limited | Real estate | 2025 |
| OK Aslan Ltd | Professional & scientific | 2025 |
| Okuden Consultancy Limited | Professional & scientific | 2025 |
| Okuk Holdings Ltd | Professional & scientific | 2014 |
| Old Burlington Holdings Limited | Real estate | 1981 |
| Old Spice Catering Ltd | Hospitality | 2024 |
| Old ST Michaels (Braintree) Limited | Households | 2009 |
| Old Tawny Holdings Limited | Real estate | 2012 |
| Oliver Financial Limited | Financial services | 2010 |
| Oliver MAY Limited | Hospitality | 2025 |
| Olivers Nurseries Limited | Wholesale & retail | 2002 |
| Omeath Property Limited | Real estate | 2024 |