| Newgen Consulting Ltd | Professional & scientific | 2019 |
| Newman Ting Productions Ltd | Arts & recreation | 2015 |
| Nexus Cavendish Ltd | Professional & scientific | 2026 |
| Nexus Funding Ltd | Financial services | 2018 |
| Nexus Property Partnership Ltd | Administrative & support | 2009 |
| Nexus Regen Ltd | Information & communication | 2023 |
| Niall Scott Ltd | Information & communication | 2013 |
| NIC & NAC Limited | Hospitality | 2022 |
| Nice and Legal Limited | Information & communication | 2018 |
| Nice Work Supplies Ltd | Wholesale & retail | 2023 |
| Nicholas Hughes Ltd | Professional & scientific | 2013 |
| Nicholson Place Estate Management (Rottingdean) Limited | Households | 2021 |
| Nick O'Shea Ltd | Education | 2025 |
| Nick Payne Marketing Ltd | Professional & scientific | 2025 |
| Nickson Motorsport Limited | Manufacturing | 2008 |
| Nigel Wilson Photography Limited | Education | 2007 |
| NIL by Mouth & Co Ltd | Extraterritorial | 2022 |
| Nimbo Health Limited | Administrative & support | 2024 |
| Nimbus Energy Limited | Mining & quarrying | 2017 |
| NIR Properties Ltd | Real estate | 2026 |
| Niton Equipment Limited | Wholesale & retail | 2000 |
| Niton Training 2001 Limited | Administrative & support | 2001 |
| Nizam Indian Restaurant Limited | Hospitality | 2003 |
| NJS Plumbing and Heating Limited | Extraterritorial | 2023 |
| NLM Contract Cleaning Ltd | Administrative & support | 2020 |
| NLW Legal Services Ltd | Professional & scientific | 2023 |
| NO More Straps Limited | Other services | 1999 |
| NO Soak Limited | Agriculture & fishing | 2007 |
| Noble Bird Ltd | Arts & recreation | 2026 |
| Noble Jester Group Limited | Extraterritorial | 2015 |
| Noco Solutions Limited | Professional & scientific | 2018 |
| Noctus Limited | Professional & scientific | 2000 |
| Noob Limited | Information & communication | 2023 |
| Nooks Properties Limited | Real estate | 2018 |
| Noor Properties Group Ltd | Real estate | 2020 |
| Nordic Life Limited | Wholesale & retail | 2011 |
| Nordic Loft Interiors Ltd | Wholesale & retail | 2021 |
| Nordica Group Ltd | Information & communication | 2023 |
| Nordren Mccall Limited | Professional & scientific | 1971 |
| Norkett Builders Limited | Construction | 2014 |
| North Highlands Partnership Limited | Professional & scientific | 2013 |
| North Horsted Farms LLP | | 2013 |
| North Laine Music Limited | Wholesale & retail | 2021 |
| North Lodge Residents Limited | Households | 2005 |
| North Ridge Films Limited | Information & communication | 2011 |
| North Western Social Development Limited | Construction | 2019 |
| Northchurch Properties Limited | Real estate | 2020 |
| Northern Blending Co.Limited | Professional & scientific | 1955 |
| Northern Clef Ltd | Arts & recreation | 2024 |
| Northern Lights Communications Ltd | Information & communication | 2024 |
| NOT Well Limited | Wholesale & retail | 2019 |
| Noughty Pictures Ltd | Information & communication | 2021 |
| Noughty State Limited | Information & communication | 2025 |
| Novabridge Global Trading Ltd | Wholesale & retail | 2026 |
| Novaro Publishing Ltd | Information & communication | 2015 |
| November 15 Limited | Information & communication | 2022 |
| Novisad Limited | Real estate | 1999 |
| Noweve Limited | Hospitality | 2016 |
| Noyon Projects Ltd | Construction | 2023 |
| NSA (1) LLP | | 2008 |
| NSW Services Ltd | Professional & scientific | 2006 |
| NTA Associates Ltd | Information & communication | 2010 |
| Nuevo Staffing Limited | Other services | 2016 |
| Nuevos Principios Limited | Professional & scientific | 2008 |
| Nugent Family Investment Company Limited | Real estate | 2025 |
| Nuhome Property Limited | Real estate | 2018 |
| Null Ængine Ltd | Information & communication | 2025 |
| Number 38 Brunswick Gardens Management Co. Limited | Households | 1979 |
| Numinous Group Limited | Information & communication | 2024 |
| Nunataq Limited | Manufacturing | 2013 |
| Nupur Restaurant Limited | Hospitality | 2013 |
| Nurelm Co. Limited | Professional & scientific | 2025 |
| Nutcracker in Havana Limited | Arts & recreation | 2024 |
| Nutrivital Supplements Ltd | Health & social care | 2001 |
| Nwave Technologies Ltd | Information & communication | 2014 |
| Nwsd Professional Services Limited | Professional & scientific | 2019 |
| NYX Editorial Ltd | Information & communication | 2023 |
| O Faolain Group Ltd | Professional & scientific | 2025 |
| Oakfield Beams & Framing Ltd | Manufacturing | 2016 |
| Oakhurst Business Systems Limited | Information & communication | 1992 |
| Oakland Construction and Landscaping Ltd | Construction | 2019 |
| Oakley Air Conditioning Limited | Construction | 1999 |
| Oakwell Executive Search Limited | Administrative & support | 2005 |
| Oakwood (Management) Limited | Households | 1958 |
| Oakwood Road Residents Association (Haywards Heath) Ltd | Households | 2022 |
| Oarfish Consultants Limited | Information & communication | 2007 |
| Oathall Veterinary Group Ltd | Professional & scientific | 2020 |
| Object Interiors Ltd | Wholesale & retail | 2021 |
| Objects by Anna Ltd | Professional & scientific | 2024 |
| Obnatus Ltd | Professional & scientific | 2018 |
| Occasio Enterprises Ltd | Wholesale & retail | 2023 |
| Occasion Wear Limited | Wholesale & retail | 2012 |
| Ocean Kind Limited | Professional & scientific | 2015 |
| Ocean Securities Limited | | 1987 |
| Octagon Events Services Ltd | Construction | 2020 |
| October Flame Ltd | Wholesale & retail | 2024 |
| Octray Ltd | Wholesale & retail | 2021 |
| ODM Legal Services Limited | Administrative & support | 2020 |
| Office Changes Limited | Construction | 2001 |
| OHK Flying Time Limited | Other services | 2024 |