| Myaccountant Sussex Ltd | Professional & scientific | 2025 |
| Mydo Limited | Health & social care | 2012 |
| N & K Property Ltd | Real estate | 2019 |
| Nadlife Limited | Manufacturing | 2025 |
| Naked & Ready Kitchen Ltd | Hospitality | 2023 |
| Naked Festivals Limited | Administrative & support | 2022 |
| Naked Vine Limited | Professional & scientific | 2022 |
| Nalroma Ltd | Other services | 2026 |
| Nanglo Ecom Limited | Wholesale & retail | 2025 |
| Nariyal Ltd | Hospitality | 2024 |
| Natal Studio Ltd | Financial services | 2026 |
| Nathan & Co Pitched Roofing Specialists Ltd | Construction | 2026 |
| National Developments Ltd | Real estate | 2015 |
| Nationwide Cleaning Solutions Ltd | Administrative & support | 2024 |
| Naturecure Academy Ltd | Wholesale & retail | 2017 |
| Nbyte Limited | Financial services | 2012 |
| Nebula Consultants Ltd | Administrative & support | 2013 |
| Nest With US Relocations Ltd | Administrative & support | 2026 |
| Netplex Networks Limited | Information & communication | 2005 |
| Network Advansys Limited | Wholesale & retail | 1998 |
| New AGE Games Limited | Information & communication | 2022 |
| New Rock Consulting Limited | Information & communication | 2024 |
| Newall Group Limited | Financial services | 2023 |
| Newall Limited | Manufacturing | 2019 |
| Newall Properties Limited | Real estate | 2023 |
| Newall Turning Limited | Manufacturing | 2023 |
| Nikl Ltd | Wholesale & retail | 2006 |
| Nios Cloud Solutions Ltd | Information & communication | 2025 |
| Nipson ADT Services Ltd | Manufacturing | 2022 |
| Nirvana Project Management Ltd | Construction | 2025 |
| NKB Design Limited | Administrative & support | 2016 |
| NMR Stone Limited | Manufacturing | 2024 |
| Nomad Trading Ltd | Arts & recreation | 2020 |
| Norman Court Residents Association Limited | Households | 2009 |
| Northcote Courier Services Limited | Transport & logistics | 2016 |
| Northern Property Investments U.K. Ltd | Administrative & support | 2018 |
| Noturk Limited | Wholesale & retail | 2026 |
| Nowhere Gallery Limited | Arts & recreation | 2024 |
| NR Travel Services Ltd | Administrative & support | 2024 |
| Nuts and Snacks LLP | | 2014 |
| Nuyu Training and Development Limited | Other services | 2022 |
| NYE Electrical Ltd | Construction | 2025 |
| O & S Building and Electrical Services Ltd | Construction | 2024 |
| O & T Properties South East Ltd | Real estate | 2025 |
| Oak and Brass Ltd | Professional & scientific | 2004 |
| Oaklands (Tollwood Park) RTM Company Limited | Households | 2019 |
| Oakley Books Ltd | Information & communication | 2011 |
| Oakway Consulting Services Limited | Professional & scientific | 2025 |
| Oarton Construction Limited | Construction | 2022 |
| Ocean Entertainment Ltd | Hospitality | 2026 |
| Ocean View Pevensey Bay Limited | Manufacturing | 2022 |
| Oceanas Lightning Protection Ltd | Construction | 2014 |
| Ocklynge Consulting Ltd | Professional & scientific | 2019 |
| Ofelo Ltd | Wholesale & retail | 2017 |
| OHM Work Ltd | Construction | 2022 |
| Olata Limited | Professional & scientific | 2007 |
| Old Town Hub Community Interest Company | Hospitality | 2020 |
| Oliver Lisa LLP | | 2019 |
| Ollie's Music Room Limited | Information & communication | 2026 |
| Olly Jones Health and Fitness Limited | Other services | 2015 |
| One Engineering Ltd | Professional & scientific | 2008 |
| One Percent Infinity Ltd | Other services | 2023 |
| One Two Sound Ltd | Information & communication | 2011 |
| Ongar Freehold Limited | Households | 2019 |
| Onion Central Limited | Information & communication | 2026 |
| Onion Labs Limited | Information & communication | 2025 |
| Only Life Ltd | Wholesale & retail | 2016 |
| ONM Project Services Ltd | Construction | 2016 |
| OPC Admin Ltd | Households | 2026 |
| Open Awareness Ltd | Professional & scientific | 2026 |
| Opus Projects Ltd | Professional & scientific | 2007 |
| ORA Electronics Limited | Construction | 2020 |
| Orangeboy Limited | Professional & scientific | 2022 |
| Organic Only Ltd | Wholesale & retail | 2021 |
| Orka Estates Limited | Real estate | 2022 |
| Osoco Ltd | Administrative & support | 2011 |
| Outrageous Insight Limited | Other services | 2017 |
| Overage Investments Limited | Real estate | 2018 |
| Overland-Farmevents Ltd | Hospitality | 2025 |
| Overland-Farmmarkets Ltd | Administrative & support | 2025 |
| Overland-Farmweddings Ltd | Hospitality | 2025 |
| Overview Financial Services Ltd | Financial services | 2017 |
| Oxbow Consulting Ltd | Professional & scientific | 2010 |
| Ozdemir Consultancy Ltd | Professional & scientific | 2019 |
| P & P Marketing Services Ltd | Professional & scientific | 2017 |
| P & S Trowell Ltd | Construction | 2026 |
| P and N Supplies Limited | Construction | 2018 |
| P J Chaffin Limited | Agriculture & fishing | 2006 |
| P.J. & S.J. Property Limited | Real estate | 2010 |
| P.J. Products Limited | Water & waste | 1998 |
| Pack Harmony Ltd | Manufacturing | 2017 |
| Palapoint Ltd | Manufacturing | 2025 |
| Panthera Private Staff Ltd | Administrative & support | 2025 |
| Park View Management (Eastbourne) Limited | Households | 1975 |
| Park Watch Limited | Transport & logistics | 2013 |
| Parker Building Supplies Limited | Wholesale & retail | 1986 |
| Parking Control Management (UK) Limited | Administrative & support | 2002 |
| Parking Group Management UK Ltd | Administrative & support | 2022 |
| Pashley Court (Eastbourne) Limited | Households | 2017 |
| Pave Investments Ltd | Professional & scientific | 2013 |