| NM Windows & Plastics Ltd | Construction | 2022 |
| NNI Security Services Ltd | Administrative & support | 2015 |
| NO 1 Bar Limited | Hospitality | 2026 |
| NO.1 Bar & Kitchen Ltd | Hospitality | 2025 |
| Noble Elegance Ltd | Other services | 2025 |
| Nonne Ltd | Other services | 2022 |
| Norcam Ltd | Water & waste | 2023 |
| Norfolk Blueprint Construction Ltd | Construction | 2019 |
| Norfolk Decorating Ltd | Construction | 2022 |
| Norfolk Essential Oils Limited | Manufacturing | 2017 |
| Norfolk Fragrances Limited | Wholesale & retail | 2025 |
| Norfolk Shellfish Company Limited | Transport & logistics | 2018 |
| Norfolk Street Delicatessen Ltd | Wholesale & retail | 2026 |
| Norfolk Timber Frames Ltd | Construction | 2013 |
| Norfolk Windows Limited | Construction | 2020 |
| Norkunas Ltd | Construction | 2026 |
| Norrie Logan Ltd | Wholesale & retail | 2019 |
| Norseman Explore Limited | Administrative & support | 2022 |
| Norseman Group Limited | Information & communication | 2021 |
| North Beach Properties Ltd | Construction | 2025 |
| Northbrink Bar & Rooms Ltd | Hospitality | 2026 |
| Northlands Farm (Thorney) Limited | Agriculture & fishing | 1977 |
| Norwich Freemasons Club Limited | Other services | 2025 |
| Norwich Masonic Centre Limited | Other services | 2025 |
| Nosey Barker Limited | Other services | 2015 |
| Novaform Ltd | Wholesale & retail | 2026 |
| Novak Accountants & Tax Advisors Ltd | Professional & scientific | 2017 |
| Novare Property Solutions Ltd | Construction | 2018 |
| Novus Workspace Solutions Limited | Construction | 2019 |
| Numanmart Limited | Wholesale & retail | 2025 |
| Number 4 York ROW Residents Management Limited | Hospitality | 1990 |
| Number 7 the Crescent Residents Management Limited | Households | 1988 |
| Number Plates 4 YOU Ltd | Wholesale & retail | 2026 |
| Nurhat Property Limited | Real estate | 2024 |
| Oakbarrel Pubs Limited | Hospitality | 2021 |
| Oakland & Co Properties Ltd | Real estate | 2024 |
| Oakley Farms Ltd | Extraterritorial | 2019 |
| Oakley Grower Services Limited | Wholesale & retail | 2014 |
| Oakley Holdings (Norfolk) Ltd | Financial services | 2019 |
| Oakley Homes (Norfolk) Ltd | Construction | 2019 |
| Oaksolutionspremium Limited | Wholesale & retail | 2025 |
| Oakway Commerce Ltd | Wholesale & retail | 2026 |
| Oakwells Group Ltd | Construction | 2025 |
| Oakwood Contract Flooring Ltd | Construction | 2025 |
| Oakwood Plant Hire Ltd | Wholesale & retail | 2005 |
| Oande Street Food Ltd | Hospitality | 2026 |
| OC Courier Ltd | Transport & logistics | 2025 |
| Ocip Ltd | Information & communication | 2023 |
| Octavia Hill Birthplace Museum Trust | Arts & recreation | 1993 |
| Octavia Hill Trading Limited | Wholesale & retail | 2008 |
| OEN Plastering Ltd | Construction | 2022 |
| Ogden Electrical Engineers Limited | Energy | 2015 |
| Ohso Shop Europe Ltd | Wholesale & retail | 2025 |
| Okenshield Construction Limited | Construction | 2016 |
| Okey Cars Ltd. | Transport & logistics | 2019 |
| Old Chapel Close Management Company Limited | Households | 2022 |
| Olive & Ward Holdings Ltd | Financial services | 2025 |
| Oliver Hartley Ltd | Transport & logistics | 2021 |
| Oliver-Phillips Developments Ltd | Real estate | 2025 |
| Omeous Cleaning Limited | Administrative & support | 2021 |
| Omnia Digital Services Limited | Extraterritorial | 2021 |
| Omnicommand Limited | Professional & scientific | 2012 |
| Omnifabric Ltd | Professional & scientific | 2005 |
| Online Marketplace Ltd | Other services | 2025 |
| Opal Engineering Solutions Ltd | Professional & scientific | 2024 |
| Opas Vending Limited | Wholesale & retail | 2025 |
| Opel Produce Limited | Administrative & support | 2008 |
| Open Arms Animal Farm CIC | Health & social care | 2025 |
| Open Arms Care & Support Services Ltd | Health & social care | 2025 |
| Open Haus Events Ltd. | Other services | 2024 |
| Open Outlet Limited | Wholesale & retail | 2025 |
| Optimum Cleaning UK Ltd | Administrative & support | 2025 |
| Optimum Packaging Limited | Manufacturing | 1998 |
| Opus (Cygnet Park) Management Company Limited | Households | 2006 |
| Orage-Events Ltd | Administrative & support | 2024 |
| Orange Square Group Limited | Financial services | 2023 |
| Ordinis Business Services Ltd | Professional & scientific | 2026 |
| Orkitchen Ltd | Wholesale & retail | 2025 |
| Ortco Management Ltd | Information & communication | 2024 |
| Orynth Ltd | Wholesale & retail | 2020 |
| Oscude Limited | Construction | 2020 |
| Osway Limited | Information & communication | 2014 |
| Outwell Timber and Building Supplies Ltd | Administrative & support | 2007 |
| Overlandsystems Ltd | Professional & scientific | 2025 |
| Ovidiu Install Ltd | Construction | 2026 |
| OW Properties (Hunstanton) Limited | Real estate | 2021 |
| Oxbo Group Ltd | Professional & scientific | 2025 |
| P & S Mason Plumbing & Heating Services Ltd | Other services | 2013 |
| P Baker & Sons Limited | Financial services | 2020 |
| P Beckett Services Limited | Construction | 2019 |
| P L C Group Limited | Real estate | 2024 |
| P R Johnson (Properties) Limited | Real estate | 2003 |
| P Winslow Butler Limited | Construction | 2018 |
| P&K Plumbing and Heating Ltd | Construction | 2025 |
| P&T SF Mechancal/Electrical Ltd | Manufacturing | 2013 |
| P. Henson Construction Limited | Construction | 2006 |
| P. J. Farms Limited | Agriculture & fishing | 1989 |
| P.K. Walker Ltd. | Real estate | 2002 |
| P.S. & J.E. Ward Ltd | Agriculture & fishing | 2007 |
| Padyma Ltd | Transport & logistics | 2025 |