| NIC Electrical Condition Reports Limited | Construction | 2025 |
| Nice Pizza Takeaway Bridgewater Ltd | Hospitality | 2024 |
| Niche Online Sales Group Ltd | Financial services | 2001 |
| Nicholas Wright Creative Limited | Professional & scientific | 2014 |
| Nicholls Event Solutions Ltd | Hospitality | 2019 |
| Nick Taylor Entertainments Limited | Arts & recreation | 2015 |
| Nigel Salter & Sons Limited | Construction | 2016 |
| Nighthawk Couriers Ltd | Transport & logistics | 2022 |
| Nightingale Stables Limited | Real estate | 2020 |
| NIL Temere Ltd | Real estate | 2005 |
| Nine AI Limited | Information & communication | 2024 |
| NJS Services Ltd | Manufacturing | 2019 |
| Nlcs Calibration Ltd | Professional & scientific | 2023 |
| NO Divide Piercing & Tattoo Limited | Other services | 2021 |
| Nodes Ventures Media Limited | Manufacturing | 2025 |
| Nonwovenn Ltd | Professional & scientific | 2016 |
| Noodle Brothers Kebab House Ltd | Hospitality | 2021 |
| NOP Intrans Limited | Transport & logistics | 2026 |
| Noppe Investments Ltd | Real estate | 2026 |
| North Petherton Bowling Club Limited | Arts & recreation | 2002 |
| North Petherton GUY Fawkes Carnival Limited | Arts & recreation | 2019 |
| North Petherton RFC Gym Limited | Arts & recreation | 2019 |
| North Petherton Rugby Football Club Limited | Arts & recreation | 2007 |
| Northern Terrace Ltd | Wholesale & retail | 2021 |
| Northwing Nurseries Limited | Agriculture & fishing | 2003 |
| Nottingham Ceramic School Ltd | Education | 2024 |
| Nova 71 Holdings Ltd | Financial services | 2025 |
| Nova Motor Company (SW) Limited | Wholesale & retail | 2026 |
| Nova Properteis Limited | Professional & scientific | 2025 |
| Nova Summits Limited | Administrative & support | 2022 |
| NR Food Hygiene Access Solutions Ltd | Construction | 2023 |
| Nrml Holdings Ltd | Financial services | 2025 |
| NRT Facilities Consulting Limited | Professional & scientific | 2007 |
| NS Training Holdings Limited | Extraterritorial | 1990 |
| NS Training Limited | Professional & scientific | 2017 |
| NSV Engineering Ltd | Professional & scientific | 2024 |
| NTM Cleaning Limited | Administrative & support | 2025 |
| Nunocho Ltd | Wholesale & retail | 2023 |
| Nurture&Nest Ltd | Real estate | 2025 |
| Nutmeg Holdings Ltd | Administrative & support | 2018 |
| Nutrixapp Ltd | Information & communication | 2025 |
| NWF Swiftpak Limited | Manufacturing | 2005 |
| O'Driscoll Group Ltd | Professional & scientific | 2023 |
| O'Neill Decorating Ltd | Construction | 2024 |
| O.B.I.S. Limited | Administrative & support | 2008 |
| O.B.I.S. Safety Limited | Administrative & support | 2008 |
| O3BIOTECH Ltd | Professional & scientific | 2016 |
| Oakenshield Property Development Ltd | Construction | 2020 |
| Oakham Management Limited | Households | 2007 |
| Oatley 2020 Limited | Agriculture & fishing | 2020 |
| OBR Holdings Limited | Real estate | 2023 |
| OBR Transport Limited | Transport & logistics | 2015 |
| Oculus Enterprises Limited | Financial services | 2024 |
| Odachi Knives Ltd | Wholesale & retail | 2022 |
| Odella Ltd | Construction | 2024 |
| Offa Systems Limited | Information & communication | 2009 |
| Ogab Limited | Professional & scientific | 2016 |
| Okeford Consulting Ltd | Professional & scientific | 2014 |
| Old Orchard Farm Kennels Limited | Other services | 2016 |
| Old School Lane Ltd | Construction | 2025 |
| Oldfield Consultancy (Group) Limited | Information & communication | 2012 |
| Olive Rose Contemporary Jewellery Limited | Wholesale & retail | 2022 |
| Oliver Blackmore Specialist GAS Engineer Limited | Construction | 2022 |
| Oliver Pomphrey Limited | Other services | 2020 |
| Omar International Limited | Wholesale & retail | 2025 |
| OME Engineering Ltd | Professional & scientific | 2025 |
| Omega Resin Ltd | Construction | 2024 |
| Ominiworks Ltd | Construction | 2024 |
| ON BIR Ltd | Construction | 2021 |
| ON the Run Vehicles Limited | Wholesale & retail | 2017 |
| One Better Place Ltd | Health & social care | 2026 |
| One Small BOY Limited | Professional & scientific | 2009 |
| One World One People Publishing Ltd | Information & communication | 2006 |
| Onhost Limited | Information & communication | 2025 |
| Onix Transcom Ltd | Transport & logistics | 2016 |
| Onslows Access Solutions Limited | Wholesale & retail | 2022 |
| Onyx Integrated International Limited | Information & communication | 2024 |
| Openmarketai Limited | Wholesale & retail | 2024 |
| Optical Property Limited | Real estate | 2024 |
| Optimise Workplace Wellbeing Ltd | Education | 2022 |
| OR Talent Limited | Professional & scientific | 2010 |
| Orange Property Lets Limited | Real estate | 2024 |
| Orchard Hill Marketing Ltd | Professional & scientific | 2026 |
| Orconsulting Limited | Other services | 1994 |
| Organisation Resource Limited | Professional & scientific | 1990 |
| Origin GIN Company Limited | Manufacturing | 2019 |
| Orproperty Limited | Construction | 1999 |
| OSH Properties Ltd | Real estate | 2025 |
| Oshpropertymaintenance Ltd | Construction | 2024 |
| Ottoland Ltd | Wholesale & retail | 2025 |
| Ottos on the Trot Ltd | Other services | 2026 |
| Ourpwr C.I.C. | Health & social care | 2026 |
| Outdoor Home and Living Ltd | Wholesale & retail | 2025 |
| Outoflineuk Ltd | Wholesale & retail | 2025 |
| Outrage LDN Ltd | Wholesale & retail | 2022 |
| Owen Walford Construction Limited | Administrative & support | 2021 |
| Oxford Eco Builders Ltd | Construction | 2025 |
| Oyster Financial Services Limited | Financial services | 2010 |
| OZ P.M. Limited | Information & communication | 2006 |
| Ozkilic Limited | Other services | 2023 |