| Special Educational Needs Expert Training & Advocacy Ltd | Education | 2018 |
| Speech Therapy North East Limited | Health & social care | 2019 |
| Speed Factory Cars Ltd | Wholesale & retail | 2025 |
| Speeding's Limited | Manufacturing | 1913 |
| Spencer Contractors Limited | Manufacturing | 2017 |
| Spenders Ltd | Wholesale & retail | 2024 |
| Spent Grain Ltd | Hospitality | 2022 |
| SPH OIL & GAS Services Ltd | Construction | 2026 |
| Spice Group Ltd | Hospitality | 2018 |
| Spice Junction Curry House Ltd | Hospitality | 2025 |
| Spice Ocean Ltd | Hospitality | 2022 |
| Spice One India Limited | Hospitality | 2024 |
| Spice One Sunderland Limited | Hospitality | 2023 |
| Spice Sunderland Ltd | Hospitality | 2019 |
| Spider Access NE Ltd | Construction | 2022 |
| Spire Crown Ltd | Real estate | 2024 |
| Spire Geotechnical Ltd | Professional & scientific | 2024 |
| Spire Property Auctions Ltd | Real estate | 2026 |
| Spire Property Group and Consultants Ltd | Real estate | 2025 |
| Spire VUE Estates Ltd | Real estate | 2023 |
| Spire VUE Lettings Ltd | Real estate | 2023 |
| Sportscape Training Ltd | Education | 2016 |
| Sportspod Limited | Professional & scientific | 2017 |
| Sprayway North East Ltd | Construction | 2021 |
| Springhaze Limited | Real estate | 1983 |
| Sprite Motorcycles Limited | Manufacturing | 2020 |
| Spritz and Spray Cleaning Ltd | Administrative & support | 2024 |
| SPS Retail Ltd | Wholesale & retail | 2025 |
| SPT Consultancy Ltd | Professional & scientific | 2022 |
| Square Ring Solutions Ltd | Administrative & support | 2026 |
| SR Coded Welding Limited | Construction | 2013 |
| SR Events Management Ltd | Hospitality | 2025 |
| SR Services Northeast Ltd | Construction | 2024 |
| SR Surveying Services Ltd | Professional & scientific | 2018 |
| SR Two Trading Ltd | Wholesale & retail | 2023 |
| SR1 Sales & Lettings Ltd | Households | 2021 |
| SR2 Interiors Ltd | Wholesale & retail | 2023 |
| SR2 Therapeutic Solutions Community Interest Company | Health & social care | 2024 |
| SR4 Limited | Hospitality | 2015 |
| SR4 Networks Limited | Information & communication | 2020 |
| SR6 Barber Ltd | Other services | 2024 |
| SR6 Developments Ltd | Real estate | 2025 |
| SR6 Inc Ltd | Construction | 2022 |
| SR6 Ltd | Wholesale & retail | 2025 |
| SRD Electrical Ltd | Construction | 2021 |
| SRD Pest Solutions Ltd | Administrative & support | 2025 |
| SRH Group Limited | Administrative & support | 2023 |
| SRI Ceylon Ltd | Hospitality | 2024 |
| SRI RAM Design Services Ltd | Professional & scientific | 2009 |
| SRI Yogi Limited | Wholesale & retail | 2024 |
| Srian Properties Limited | Real estate | 2021 |
| SRS OFF Licence Store Ltd | Wholesale & retail | 2021 |
| Ssasco Administration Limited | Financial services | 2022 |
| Ssasco Limited | Financial services | 2014 |
| Ssggroupne Ltd | Professional & scientific | 2025 |
| SSK Studio Limited | Real estate | 2025 |
| SSL Trading Ltd | Other services | 2026 |
| ST Benedict's Hospice, Sunderland | Health & social care | 1993 |
| ST Wind Limited | Construction | 2026 |
| ST. Marks Home Limited | Health & social care | 1994 |
| Stable Distribution Limited | Wholesale & retail | 2011 |
| STACKYARD26 Ltd | Hospitality | 2026 |
| Stadium Motors Limited | Wholesale & retail | 2019 |
| Stadium Stone NE Ltd | Manufacturing | 2023 |
| Staff Power Group Limited | Administrative & support | 2018 |
| Staff Power Group Properties Ltd | Real estate | 2023 |
| Staff Power Training Limited | Education | 2019 |
| Stafford Accountancy Limited | Professional & scientific | 2020 |
| Stage Left Productions Limited | Construction | 2007 |
| Staley & Jones Ltd | Professional & scientific | 2023 |
| Stanmascot Limited | Information & communication | 2025 |
| Stapleton International Emea Limited | Mining & quarrying | 2014 |
| Star Accountancy Limited | Professional & scientific | 2022 |
| Star Mitra Ltd | Hospitality | 2025 |
| Star Pizza Sunderland Ltd | Hospitality | 2019 |
| Starry Productions Limited | Wholesale & retail | 2013 |
| Starshine Recycling Ltd | Manufacturing | 2024 |
| Station Taxis (Sunderland) Limited | Transport & logistics | 1985 |
| Stay DRY Dampproofing Ltd | Construction | 2025 |
| Stcc Ltd | Hospitality | 2025 |
| Steel Fencing Limited | Manufacturing | 1995 |
| Steel Invader Ltd | Hospitality | 2024 |
| Steerwheel Autos Limited | Wholesale & retail | 2026 |
| Steinbuild Ltd | Construction | 2025 |
| Stellar Business Events Limited | Administrative & support | 2024 |
| Stem Buddies Community Interest Company | Education | 2025 |
| Stemtalents Education Community Interest Company | Professional & scientific | 2025 |
| Step in Care Limited | Administrative & support | 2020 |
| Stepfel Limited | Other services | 2017 |
| Steph Leisure Limited | Hospitality | 2018 |
| Stephen Balls Limited | Professional & scientific | 2007 |
| Stephen Frater Joinery Limited | Administrative & support | 2017 |
| Stephenson Ventures Limited | Professional & scientific | 2016 |
| Sterling Staffing Ltd | Administrative & support | 2022 |
| Steven Freeman Fitness Ltd | Arts & recreation | 2024 |
| Steven Stewart Limited | Construction | 2004 |
| Steven Watson Scaffolding Ltd | Construction | 2025 |
| Steven Wilkinson Blade Repair Ltd | Manufacturing | 2019 |
| Steward Stick Limited | Wholesale & retail | 2025 |
| Sthi Catering Limited | Hospitality | 2023 |