| PSK Convenience Store Limited | Wholesale & retail | 2021 |
| PUMPSDIRECT2U Limited | Wholesale & retail | 2008 |
| Purvis Leisure Limited | Hospitality | 2019 |
| Pwmorland Ltd | Professional & scientific | 2021 |
| Quality Ascend Ltd | Professional & scientific | 2022 |
| Quant X Consult Ltd | Professional & scientific | 2025 |
| Quickfood Seaham Ltd | Hospitality | 2019 |
| Quilo Ltd | Financial services | 2024 |
| R Akenhead Logistics Limited | Transport & logistics | 2025 |
| R S Express Distribution & Haulage Limited | Transport & logistics | 2011 |
| Rainbows Sensory Space Ltd | Arts & recreation | 2020 |
| RAL Property Investments Ltd | Real estate | 2022 |
| Ranya Pizza Shop Ltd | Hospitality | 2025 |
| Rapid Bifolds NE Ltd | Manufacturing | 2022 |
| Rapid Glazing (North East) Limited | Construction | 2012 |
| Rapid Windows (North East) Limited | Construction | 2012 |
| Ratnaam Ltd | Wholesale & retail | 2021 |
| Raven Forestry and Land Management Limited | Agriculture & fishing | 2025 |
| React Architectural Metalwork (North-East) Limited | Manufacturing | 2009 |
| Red Hot Property Group Limited | Real estate | 2019 |
| Redu Group Ltd | Other services | 2014 |
| Redu Holdco Ltd | Other services | 2022 |
| Regency Premium Ltd | Wholesale & retail | 2024 |
| Rent a Reindeer Limited | Other services | 2013 |
| Retroflo Limited | Construction | 2007 |
| RG Distributors Limited | Wholesale & retail | 2011 |
| Rhodium Trading Ltd | Wholesale & retail | 2016 |
| Ribbon Academy Trust | Education | 2012 |
| Ribbon Daycare Ltd | Education | 2006 |
| Rich Tech Wind Limited | Manufacturing | 2022 |
| Richard Mclane GAS Services Limited | Construction | 1999 |
| Richardson Renewable Consultants(R.R.C) Ltd | Financial services | 2024 |
| Rish & SAN Limited | Wholesale & retail | 2019 |
| RJ Akenhead Logistics Ltd | Transport & logistics | 2025 |
| RMC Services Limited | Construction | 2025 |
| RMH Lamps, Lighting & Electrical Limited | Construction | 2006 |
| Rmmb Investments Ltd | Real estate | 2025 |
| RMR Electrical Services Ltd | Manufacturing | 2018 |
| Robert Gale and Company Limited | Professional & scientific | 2012 |
| Robertson Wines Ltd | Wholesale & retail | 2019 |
| Robinson Brown Design Ltd | Professional & scientific | 2022 |
| Robinsons Biomass UK Limited | Professional & scientific | 2014 |
| Robinsons UK Heating Academy North Ltd | Education | 2025 |
| Robson Renovations Ltd | Construction | 2016 |
| Roker Estates Limited | Real estate | 2018 |
| Romlily Pets Ltd | Agriculture & fishing | 2024 |
| Romlily Properties Ltd | Real estate | 2023 |
| Rose Grangeway Ltd | Financial services | 2015 |
| Rowland Partnership Ltd | Professional & scientific | 2025 |
| RPS (NE) Limited | Construction | 2025 |
| RS Express Storage Limited | Transport & logistics | 2017 |
| Ryan Luke Consulting Ltd | Professional & scientific | 2022 |
| Ryan Youll Limited | Construction | 2014 |
| S Brothers NE Transport Ltd | Transport & logistics | 2024 |
| S&H Home Group Limited | Real estate | 2025 |
| S1MB4 Ltd. | Wholesale & retail | 2024 |
| S2 Consulting Ltd | Professional & scientific | 2024 |
| Sa&I Limited | Wholesale & retail | 2025 |
| Safety 365 Ltd | Administrative & support | 2026 |
| Safety Service Solutions Ltd | Public administration | 2025 |
| Safety-Logic (Health, Safety, Compliance) Ltd | Professional & scientific | 2022 |
| Sair Bar Samrat Ltd | Hospitality | 2024 |
| Sambuca Seaham Ltd | Hospitality | 2018 |
| Sapper Project Limited | Professional & scientific | 2022 |
| Scamans Limited | Wholesale & retail | 2015 |
| Scasnet Creative Limited | Arts & recreation | 2026 |
| SE Rigging & Lifting Ltd | Professional & scientific | 2022 |
| Seaburn Leisure Limited | Hospitality | 2020 |
| Seaham Auto Salvage Ltd | Wholesale & retail | 2020 |
| Seaham Caravan Sales Limited | Wholesale & retail | 2017 |
| Seaham Coaches Ltd | Transport & logistics | 2021 |
| Seaham EIT Limited | Other services | 2015 |
| Seaham Harbour Community Interest Company | Transport & logistics | 2011 |
| Seaham Harbour Cricket Club | Arts & recreation | 2006 |
| Seaham Harbour Cricket Club Enterprises Limited | Arts & recreation | 2007 |
| Seaham Hospitality Ltd | Hospitality | 2024 |
| Seaham Indians Ltd | Hospitality | 2026 |
| Seaham Life Limited | Hospitality | 2020 |
| Seaham Lighthouse Ltd | Hospitality | 2022 |
| Seaham Metals Limited | Water & waste | 2012 |
| Seaham Park Social Club CIC | Arts & recreation | 2024 |
| Seaham Pet Crematorium Limited | Other services | 2023 |
| Seaham Pets, Gardens and Reptiles Limited | Wholesale & retail | 2008 |
| Seaham Safety Services Ltd | Health & social care | 2006 |
| Seaham Tandoori (NE) Ltd | Hospitality | 2016 |
| Seaham Targets Air Rifle Range CIC | Arts & recreation | 2026 |
| Seaham Vets Limited | Professional & scientific | 2013 |
| Seaham Windows Doors & Conservatories Limited | Construction | 2015 |
| Seaton Supply Stores Limited | Wholesale & retail | 2008 |
| Seaton Village Development Consortium LLP | | 2016 |
| Seaview Plastics Ltd | Manufacturing | 1995 |
| Service Xperts Ltd | Administrative & support | 2025 |
| Servved Holdings Limited | Financial services | 2024 |
| Seylux Limited | Wholesale & retail | 2017 |
| Shannara Company Limited | Manufacturing | 2022 |
| Sharpley Consultancy Ltd | Professional & scientific | 2021 |
| Shemoli Catering Services Limited | Hospitality | 2023 |
| Shop by Shape Ltd | Information & communication | 2015 |
| Simulations Limited | Professional & scientific | 1985 |
| Sitasham Tech Limited | Wholesale & retail | 2025 |