| Optimum Controls (UK) Ltd | Information & communication | 2009 |
| Opulent Holdings Ltd | Real estate | 2022 |
| Opulent Holdings North Limited | Real estate | 2025 |
| Opulentink Ltd | Other services | 2026 |
| Oracle Financial Planning Limited | Financial services | 2008 |
| Orange Box Self Storage Ltd | Transport & logistics | 2000 |
| Orange Box Storage Ltd | Administrative & support | 2017 |
| Orange John CIC | Arts & recreation | 2022 |
| Orangefox Day Nurseries Limited | Health & social care | 2024 |
| Orca GAS Installations N.E. Limited | Construction | 2021 |
| Orchard Garden Properties Limited | Construction | 2013 |
| Orchid Aesthetics Limited | Health & social care | 2012 |
| Orchid Beauty & Skin Ltd | Wholesale & retail | 2022 |
| Orcrist (Management) Limited | Households | 1995 |
| Orgarifa Ltd | Wholesale & retail | 2026 |
| Origin Alloy Limited | Manufacturing | 2011 |
| Origin OIL and GAS Ltd | Other services | 2016 |
| Orion Express Ltd | Transport & logistics | 2025 |
| Orion Holdings 1 Limited | Financial services | 2025 |
| Orion Holdings 2 Limited | Financial services | 2025 |
| Orlix Ltd | Hospitality | 2026 |
| Oromo in Newcastle Ltd | Other services | 2026 |
| Osas African Foods Sunderland Ltd | Wholesale & retail | 2024 |
| Oskel Ltd | Wholesale & retail | 2026 |
| Ossn Ltd | Wholesale & retail | 2024 |
| Osuk Limited | Wholesale & retail | 2024 |
| Osvaldas Services Ltd | Wholesale & retail | 2024 |
| Otaffairzuk Limited | Wholesale & retail | 2025 |
| Otisbum Limited | Construction | 2024 |
| Otricon Ltd | Information & communication | 2009 |
| Otto Sunderland Ltd | Hospitality | 2026 |
| Ottoman 1 Barber Ltd | Other services | 2025 |
| OUT There Adventures Community Interest Company | Education | 2022 |
| Outstanding Dynasty Limited | Real estate | 2022 |
| OUX Commerce Ltd | Wholesale & retail | 2026 |
| Oven & Grill Hexham Ltd | Hospitality | 2017 |
| Owben Ltd | Manufacturing | 2012 |
| Owen Campbell Ltd | Information & communication | 2017 |
| Owen Technical Services Limited | Professional & scientific | 1980 |
| OXC Homes Ltd | Real estate | 2024 |
| Oxley Renewable Services Ltd | Manufacturing | 2026 |
| Oyanju Limited | Health & social care | 2025 |
| OZ Greek Ltd | Hospitality | 2026 |
| O’Brien Container and Storage (Holdings) Limited | Financial services | 2024 |
| O’Brien Family Holdings Limited | Financial services | 2025 |
| O’Brien Finance Company Limited | Professional & scientific | 2024 |
| P & N Catering Ltd | Hospitality | 2025 |
| P & T Salisbury Ltd | Wholesale & retail | 2025 |
| P Darling Properties Limited | Real estate | 2024 |
| P R Construction (North East) Limited | Construction | 2021 |
| P&C Renovation Ltd | Construction | 2022 |
| P&L Properties (Sunderland) Limited | Real estate | 2021 |
| P&R Neesham Ltd | Administrative & support | 2021 |
| P&S Bookkeeping Services Limited | Professional & scientific | 2013 |
| P.P.G. Property Ltd | Real estate | 2011 |
| Paad Ltd | Manufacturing | 2019 |
| Pabmary Limited | Health & social care | 2025 |
| PAC Renewable Energy Ltd | Professional & scientific | 2025 |
| Pacewell Entertainment Ltd | Information & communication | 2010 |
| Pacino Birtley Ltd | Hospitality | 2025 |
| Pacs Facilities Management Limited | Real estate | 2007 |
| Page Bespoke Paint Specialists Ltd | Construction | 2018 |
| Page Bespoke Spraying and Design Ltd | Professional & scientific | 2025 |
| Pagrams Holdings Ltd | Professional & scientific | 2024 |
| Palace Road Pizza Ltd | Hospitality | 2026 |
| Palak Traders Ltd | Hospitality | 2025 |
| Pallion Action Group | Health & social care | 1996 |
| Pallion Engineering Limited | Manufacturing | 1991 |
| Pallion Enterprise Ltd | Wholesale & retail | 2021 |
| Pallion Foods Ltd | Hospitality | 2018 |
| Pallion Investments & Developments Limited | Construction | 2024 |
| Pallion Nails Ltd | Other services | 2023 |
| Palm Environmental Ltd | Water & waste | 2018 |
| Pams Property Ltd | Health & social care | 2022 |
| Pamsodyssey Ltd | Wholesale & retail | 2026 |
| PAN Africa Network CIC | Other services | 2020 |
| Panache Property Group Limited | Real estate | 2021 |
| Panda Motor Vehicles Ltd | Wholesale & retail | 2012 |
| Pape Engineering Services Ltd | Construction | 2023 |
| Paralegal Services Sunderland Ltd | Professional & scientific | 2023 |
| Parallel Studios Newcastle Ltd | Other services | 2026 |
| Param Stores Ltd | Wholesale & retail | 2024 |
| Paramountpaintco Ltd | Wholesale & retail | 2025 |
| Pareda Recruitment Ltd | Administrative & support | 2018 |
| Parent Properties Limited | Real estate | 2013 |
| Parica Ltd | Extraterritorial | 2019 |
| Park Grange Advanced Skin Clinic Limited | Other services | 2020 |
| Park Lane Cards (Sunderland) Ltd | Wholesale & retail | 2012 |
| Park Lane NE Ltd | Hospitality | 2010 |
| Parker and Dodds Property Services Limited | Construction | 2024 |
| Parkers (North East) Limited | Administrative & support | 1998 |
| Parkers Rental Properties Ltd | Real estate | 2023 |
| Parker’S Autism Journey Ltd | Manufacturing | 2024 |
| Parlour Product Holding Limited | Wholesale & retail | 2008 |
| Parlour Product Topco Limited | Wholesale & retail | 2008 |
| Partner Pairs Ltd | Wholesale & retail | 2025 |
| Parts Purchasing Solutions Limited | Wholesale & retail | 2008 |
| Party Poppers Events Ltd | Other services | 2022 |
| Party Strip UK Limited | Other services | 2014 |
| Pascal Tamburrino Limited | Hospitality | 2022 |