| MJ Steelift Ltd | Construction | 2016 |
| MJP Gold Ltd | Wholesale & retail | 2025 |
| MJR Lighting Consultants Ltd | Professional & scientific | 2022 |
| Monarch Construction Ltd | Construction | 2025 |
| Moorezzzleep Ltd | Wholesale & retail | 2016 |
| Moorings Freehold Limited | Households | 1979 |
| Morr Properties Ltd | Real estate | 2020 |
| Motion Label Group Ltd | Information & communication | 2016 |
| MPR Service Ltd | Construction | 2012 |
| MR Clean ( Sussex ) Ltd | Other services | 2015 |
| Mrtgolf Limited | Manufacturing | 2025 |
| Mshaty Clinical & Consultancy Ltd | Health & social care | 2026 |
| MTM Building Contractors Ltd | Construction | 2023 |
| Murray and Yeatman Distilleries Ltd | Manufacturing | 2019 |
| Musson Osteopathic Services Limited | Health & social care | 2022 |
| MW Landscapes Sussex Ltd | Administrative & support | 2021 |
| My Personal Enablement Support Partnership Community Interest Company | Real estate | 2018 |
| N & B Property Management Ltd | Real estate | 2018 |
| N & E Seaford Ltd | Wholesale & retail | 2016 |
| N M Plumbing & Heating Limited | Construction | 2010 |
| N V L Property Services Limited | Construction | 2018 |
| N.F. Construction and Driveways Ltd | Construction | 2007 |
| Nadp Ltd | Real estate | 2018 |
| Nails by US Limited | Other services | 2024 |
| Nalroh Property Limited | Real estate | 2019 |
| Narrative Workshops Community Interest Company | Education | 2026 |
| Neal Grundy Photography Ltd | Professional & scientific | 2022 |
| Nemeton Services Ltd | Information & communication | 2022 |
| Nereus Property Ltd | Real estate | 2024 |
| Nereus Real Estate Ltd | Real estate | 2025 |
| New S R Ltd | Hospitality | 2018 |
| Newberry Tully Limited | Real estate | 2010 |
| Newcastle ARM Ltd | Professional & scientific | 2025 |
| Newhaven and Seaford Sailing Club Limited(The) | Arts & recreation | 1976 |
| Newhaven Marine Services Limited | Manufacturing | 1985 |
| Newsel Solutions Limited | Professional & scientific | 2015 |
| NO. 1 Pallmore Limited | Real estate | 2010 |
| Norman Baker Enterprises Limited | Information & communication | 2015 |
| Nova Business Intelligence Limited | Administrative & support | 2015 |
| Novabit I.T. Services Limited | Information & communication | 2018 |
| Null Dokuro Limited | Information & communication | 2025 |
| Oakin Extreme Ltd | Wholesale & retail | 2024 |
| Oakleaf and Windsor Management Company Limited | Households | 1980 |
| Old Orchard Road Freehold Company Limited | Households | 2018 |
| Old Orchard Road Management Company Limited | Households | 2008 |
| Old Poplar Close (Seaford) Management Company Limited | Households | 2021 |
| Olus Kitchen (UK) Limited | Hospitality | 2024 |
| One Another Music Ltd | Information & communication | 2016 |
| ONE1PERCENTCLUB Limited | Education | 2025 |
| Orange Stripe Limited | Real estate | 2007 |
| Orchard Dental Group Limited | Health & social care | 2017 |
| Organic Optimisation Ltd | Health & social care | 2025 |
| Orthotic and Rehabilitation Services Ltd | Health & social care | 2025 |
| Ouse Valley Property Market Limited | Real estate | 2013 |
| Ovotech Ltd | Administrative & support | 2009 |
| Pallmore Limited | Real estate | 1992 |
| Palmeira Entertainment Limited | Education | 2007 |
| Paradoxica Ltd | Information & communication | 2026 |
| Parker Signalling Limited | Professional & scientific | 2021 |
| Parkside Close Management Company Limited | Households | 2019 |
| Pass & Move Ltd | Information & communication | 2019 |
| Pass NOW Ltd | Other services | 2013 |
| Patamona Limited | Wholesale & retail | 2024 |
| Paul Gasson Building Limited | Construction | 2026 |
| Pavilion Design Consultancy Limited | Construction | 2014 |
| PCS Export Services Limited | Wholesale & retail | 2006 |
| Peaceful Pathways Ltd | Health & social care | 2025 |
| Peak Aero Limited | Administrative & support | 2002 |
| Pearl Court (Eastbourne) Limited | Households | 1992 |
| Pearl Skin Studio Ltd | Other services | 2023 |
| Pelham Property Management Ltd. | Households | 1987 |
| Pelo (Seaford) Limited | Other services | 2014 |
| Penrose Wills Limited | Professional & scientific | 2020 |
| Perfect Dimension Studios Ltd | Information & communication | 2012 |
| Perfield Holdings Limited | Administrative & support | 2024 |
| Peter Wilson Accountancy Limited | Professional & scientific | 2000 |
| Phil Chapman Builders Ltd | Construction | 2003 |
| Phoenix Counselling and Psychology Ltd | Health & social care | 2022 |
| Phoenix Osteopathic & Wellbeing Ltd | Administrative & support | 2018 |
| Photobooth IT NOW Ltd | Professional & scientific | 2025 |
| Pickd Ltd | Information & communication | 2021 |
| Pigster Inns Limited | Hospitality | 2020 |
| Pilates Avenue Limited | Arts & recreation | 2026 |
| PKW Events Ltd | Hospitality | 2019 |
| Platinum Cuisine Ltd | Real estate | 2021 |
| Platinum Heating & Plumbing Sussex Ltd | Construction | 2025 |
| PMR Offshore Ltd | Mining & quarrying | 2018 |
| Pointz Limited | Real estate | 2025 |
| Pola Vapes Limited | Wholesale & retail | 2026 |
| Polling & Associates Limited | Construction | 2002 |
| Pooleys Flight Instructor School Ltd | Education | 2017 |
| Port Regent (Phase III) Management Limited | Households | 2000 |
| Port Regent (Phase V) Limited | Households | 2001 |
| Positive Touch Therapy Ltd | Other services | 2018 |
| Powell Gardens (Newhaven) NO. 1 Managements Limited | Households | 1974 |
| PR Properties Seaford Ltd | Real estate | 2025 |
| Premier Lets and Sales Limited | Real estate | 2005 |
| Premier Polygraph Services Ltd | Administrative & support | 2018 |
| Premonition Design Ltd | Administrative & support | 2003 |
| Present Truth Ltd | Arts & recreation | 2025 |