| Osprey Capital Management | Professional & scientific | 2018 |
| Osteris Logistics Ltd | Transport & logistics | 2013 |
| Ostrich Software Limited | Information & communication | 1997 |
| OTH Electrical Ltd | Construction | 2025 |
| Other Island Films Limited | Information & communication | 2021 |
| OTR ICT Services Limited | Information & communication | 2007 |
| Ottocento Ltd. | Arts & recreation | 2012 |
| Ottway Full Media Solutions Limited | Professional & scientific | 2026 |
| Ottway Media Solutions Ltd | Professional & scientific | 2015 |
| OUR Lady of Sion School, Worthing | Education | 2007 |
| OUR Minds CIC | Health & social care | 2015 |
| OUR Property UK Solutions Ltd | Construction | 2026 |
| OUR Rainbow Cafe Ltd | Hospitality | 2024 |
| OUR Tiny Tribe Limited | Information & communication | 2021 |
| OUR World OUR SAY | Administrative & support | 2003 |
| Ourcafe Ltd | Hospitality | 2023 |
| OUT Cold Media Ltd | Information & communication | 2024 |
| OUT of Nowhere Properties Limited | Real estate | 2013 |
| Outer Heaven Limited | Information & communication | 2020 |
| Outreach Talent Group Limited | Professional & scientific | 2017 |
| Oval Carpentry Company Limited | Construction | 2017 |
| Overhaul Property Developments Limited | Construction | 2013 |
| Overline Holdings Limited | Professional & scientific | 2017 |
| Overline IT Limited | Extraterritorial | 2019 |
| Overline Limited | Extraterritorial | 2006 |
| Overline Network Consultants Limited | Information & communication | 1995 |
| OVERRIDE13 Ltd | Professional & scientific | 2023 |
| Overstrand West Estates Limited | Households | 1984 |
| Overthought Entertainment Ltd | Information & communication | 2022 |
| Overwatch Medical Ltd | Health & social care | 2021 |
| Owen Monie Limited | Wholesale & retail | 2004 |
| Oxford Road (NO16) Management Co Ltd | Households | 2010 |
| Oyster DM Ltd | Professional & scientific | 2025 |
| OZ Charcoal Grill Limited | Hospitality | 2026 |
| OZ Property Sussex Ltd | Real estate | 2023 |
| Ozer Bespoke Leather Goods Limited | Manufacturing | 2021 |
| P & D Electrical Services Sussex Ltd | Construction | 2025 |
| P & L Marley Ltd | Real estate | 2018 |
| P a N Grimley Limited | Professional & scientific | 2005 |
| P B Blanks Limited | Construction | 2011 |
| P GUY 1 Ltd | Hospitality | 2025 |
| P GUY Ltd | Hospitality | 2025 |
| P L Projects Limited | Construction | 2010 |
| P Levvy Rigging Limited | Information & communication | 2025 |
| P Morris Carpentry Limited | Construction | 2010 |
| P R J Bathrooms Limited | Construction | 2023 |
| P R Precision Engineering Limited | Manufacturing | 1999 |
| P Squared Investments Ltd | Real estate | 2019 |
| P Towse Programme Management Ltd | Professional & scientific | 2014 |
| P Wise Limited | Professional & scientific | 2021 |
| P&C Property Services Limited | Real estate | 2019 |
| P&H Autos and Engineering Ltd | Wholesale & retail | 2008 |
| P&J Traders Ltd | Wholesale & retail | 2018 |
| P&Sb Limited | Construction | 2011 |
| P. Hoeben & Sons Ltd | Real estate | 2018 |
| P.B. Davis Insurance Services UK Limited | Financial services | 2005 |
| P.B. Extrusions Limited | Extraterritorial | 1982 |
| P.J. Roberts Investments Ltd. | Real estate | 2021 |
| P.Varun Ltd | Wholesale & retail | 2014 |
| P.W.Anderson and Woodman Bros.,Limited | Real estate | 1951 |
| P1 Podcast Ltd | Arts & recreation | 2023 |
| P2G Associates Ltd | Professional & scientific | 2024 |
| Paac Ltd | Professional & scientific | 2018 |
| Paal Properties Consultancy Ltd | Real estate | 2017 |
| PAC Worldwide UK Ltd | Manufacturing | 2018 |
| Pacaluca Ltd | Education | 2000 |
| Pacani Ltd | Wholesale & retail | 2023 |
| Pacific Court(Shoreham Beach)Management Company Limited | Households | 1976 |
| PAD 26 Limited | Information & communication | 2018 |
| Paddock Way Land Management Limited | Real estate | 2023 |
| Paddocks Way (Ferring) Limited | Households | 2002 |
| Padgham (Portslade) Management Company Limited | Households | 1982 |
| PADS4LABS Limited | Manufacturing | 2014 |
| Padwick Builders and Flooring Ltd | Construction | 2018 |
| Padwick Builders Limited | Construction | 1998 |
| Page Financial Planning Limited | Professional & scientific | 2020 |
| Pagett-Fynn Holdings Limited | Real estate | 1975 |
| Pain Car Sales Limited | Wholesale & retail | 1979 |
| Pain Genie Limited | Health & social care | 2008 |
| Paine Manwaring Group Limited | Financial services | 2015 |
| Paine Manwaring Heating Limited | Construction | 1998 |
| Paine Manwaring Limited | Construction | 1992 |
| Paine, Manwaring, & Lephard, Public Limited Company | Real estate | 1903 |
| Painting Hands Ltd | Administrative & support | 2016 |
| Palace Plasterwork Limited | Construction | 2011 |
| Palantir Business Group Ltd | Financial services | 2011 |
| Palfrey Investments Limited | Real estate | 2023 |
| Palladian Asset Management Limited | Real estate | 2000 |
| Palladian Real Estate Limited | Real estate | 2000 |
| Pallet Handling Penshurst Limited | Manufacturing | 2005 |
| Pallet Truck Services Limited | Wholesale & retail | 1995 |
| Palletstore Sussex Limited | Transport & logistics | 2024 |
| Palm Court Catering Ltd | Hospitality | 2015 |
| Palmer Groundworks Ltd | Construction | 2025 |
| Palmers Healthcare Ltd | Health & social care | 2019 |
| Palmoris Ltd | Real estate | 2025 |
| Panamac Limited | Construction | 2020 |
| Panashe Property Ltd | Real estate | 2022 |
| Panco Solutions Limited | Information & communication | 2011 |
| Pancredit Systems Ltd. | Information & communication | 1988 |