| NO Holds Barred Pictures Ltd | Information & communication | 2023 |
| NO Mess Services Ltd | Administrative & support | 2022 |
| NO. 47 Properties Limited | Real estate | 1999 |
| NO. 83 Properties Limited | Real estate | 2014 |
| Noble Craft Brewing Limited | Manufacturing | 2020 |
| Nobold Barns Management Limited | Households | 2010 |
| Nobold Holsteins Ltd | Agriculture & fishing | 2025 |
| Nodsboy Ltd | Manufacturing | 2025 |
| Noel Architecture and Design Ltd | Professional & scientific | 2023 |
| Noir Empire Ltd | Information & communication | 2025 |
| Nomadic Designer Ltd | Professional & scientific | 2019 |
| Noor Ayman Limited | Extraterritorial | 2020 |
| Norfolk Square Mews Management Company Limited | Households | 2023 |
| Normanton Services Limited | Administrative & support | 2025 |
| North Farm Poultry Limited | Agriculture & fishing | 2017 |
| North Housing Consulting Limited | Construction | 2013 |
| North Minden House Management Company Limited | Households | 1988 |
| North Shropshire Construction Limited | Construction | 2018 |
| North Shropshire Lamb Ltd | Agriculture & fishing | 2025 |
| North West Fire Prevention Ltd | Other services | 2019 |
| North Western Steamship Co. Limited | Arts & recreation | 1977 |
| Northern Anchorage (ST Matthews Court) Limited | Households | 1987 |
| Northgate Court Management Company (Chester) Limited | Households | 1989 |
| Northway Management Company (NO.1) Limited | Households | 2003 |
| Northwood PUB Company Ltd | Hospitality | 2019 |
| Norton Aggregates Ltd | Transport & logistics | 2025 |
| Norwegian Seaways Limited | Transport & logistics | 2012 |
| Notepad Communications Limited | Administrative & support | 2017 |
| Notitia Limited | Professional & scientific | 2007 |
| Notorious Family Ltd | Information & communication | 2024 |
| Nouvelle Frame Ltd | Information & communication | 2026 |
| Novo Property (Oxford) Ltd | Real estate | 2026 |
| Novo Property Development Ltd | Real estate | 2021 |
| Nowrozi Property Investment Ltd | Real estate | 2026 |
| NPB Construction Limited | Construction | 2019 |
| Nrkk Contractors Ltd | Construction | 2024 |
| Nsmnet Ltd | Information & communication | 2026 |
| NTC (UK) Car Workshop Limited | Wholesale & retail | 2025 |
| Nudge.Direct Limited | Administrative & support | 2018 |
| Nudie Jewellery Ltd | Manufacturing | 2024 |
| Number One Barbers Ltd | Other services | 2020 |
| Numbero Ltd | Professional & scientific | 2019 |
| Nutrio Media Ltd | Professional & scientific | 2026 |
| NVP Developments Ltd | Construction | 2024 |
| NWK Valeting Ltd | Other services | 2016 |
| Nye-Uk Ltd | Professional & scientific | 2021 |
| Nyne Services PVT Ltd | Information & communication | 2007 |
| Nyssa Care UK Ltd | Professional & scientific | 2021 |
| O & R Projects Ltd | Construction | 2025 |
| O. J. Croft Tiling Limited | Other services | 2005 |
| Oak Apple Catering Ltd | Hospitality | 2014 |
| Oak Medical Ltd | Health & social care | 2025 |
| Oak Ridge Medical Services Ltd | Health & social care | 2015 |
| Oak Tree Close Management Company Limited | Households | 2011 |
| Oak Tree Gardens (Audley) Management Company Limited | Real estate | 2019 |
| Oak Tree Gardens (Hugglescote) Management Limited | Real estate | 2016 |
| Oakenseed Studios Ltd | Information & communication | 2021 |
| Oakfield (1999 Management) Limited | Households | 1999 |
| Oakfield Carpentry & Construction Ltd | Manufacturing | 2022 |
| Oakfield NO 1 Management Company (Tiverton) Limited | Households | 2003 |
| Oakland Grange Management Company Limited | Households | 1999 |
| Oaklands Hooton Limited | Financial services | 2019 |
| Oaklands Management Company (Bromsgrove) Limited | Households | 1997 |
| Oaklands Proprietors Limited | Households | 1983 |
| Oaklea Square Management Company Ltd | Households | 2007 |
| Oakley Brothers Developments Ltd | Real estate | 2023 |
| Oakley Farming Ltd | Agriculture & fishing | 2010 |
| Oakley Farms Holding Limited | Financial services | 2024 |
| Oakley Meadow Management Company Limited | Real estate | 2016 |
| Oakley Place Ltd | Professional & scientific | 2016 |
| Oakley Way (Outwell) Management Company Limited | Real estate | 2024 |
| Oakleys Group Limited | Wholesale & retail | 2020 |
| Oakview Residents Management Company Limited | Real estate | 2004 |
| Oakwood Farm (Services) Limited | Agriculture & fishing | 2014 |
| Oakwood Gardens Management Limited | Households | 2020 |
| Oasis (Wolseley Road) Management Limited | Households | 2005 |
| Oatland Trade Ltd | Wholesale & retail | 2018 |
| Oberon Clothing & Accessories Ltd | Wholesale & retail | 1999 |
| Oberon Engineering Services Limited | Professional & scientific | 1998 |
| Oceanfresh in A2Z Limited | Wholesale & retail | 2025 |
| October Solutions Limited | Other services | 2012 |
| Odyssey Studio Ltd | Information & communication | 2018 |
| OE Developments Ltd | Construction | 2010 |
| OET Global Ltd | Education | 2026 |
| OF & G Trading Limited | Extraterritorial | 1994 |
| Of&G (Scotland) Ltd | Extraterritorial | 2015 |
| Oferlooked CIC | Information & communication | 2026 |
| Offsite Media Limited | Information & communication | 2022 |
| Ohsd Ltd | Financial services | 2022 |
| Ojas 888 Ltd | Professional & scientific | 2020 |
| OJO Capital Limited | Real estate | 2022 |
| OJO Investments Ltd | Financial services | 2020 |
| Ojrw Holdings Ltd | Financial services | 2018 |
| Ojrw Property Ltd | Professional & scientific | 1999 |
| Ojuju Calaba Limited | Health & social care | 2021 |
| Old Cider Works Management Company Limited | Real estate | 2008 |
| Old Coleham Court Property Management Limited | Households | 2024 |
| Old Comrades Light Infantry CIC | Education | 2025 |
| Old Cottage Gardens Management Ltd | Real estate | 2023 |
| Old Earlstone Ltd | Construction | 1994 |