| Skull Company Ltd | Wholesale & retail | 2022 |
| SMC Vision Limited | Transport & logistics | 2025 |
| Smiths Technical Services Ltd | Professional & scientific | 2026 |
| Snowfast Limited | Real estate | 1999 |
| Sober Homes Ltd | Health & social care | 2008 |
| Society of Buildings and Health Ltd | Other services | 2020 |
| Society of Surveying and Construction Ltd | Construction | 2020 |
| Socraflix Ltd | Education | 2025 |
| SOH Property Services Ltd | Real estate | 2023 |
| Sollett Bros Limited | Construction | 1988 |
| Souuthe Ltd | Health & social care | 2023 |
| Sparklegranite Limited | Manufacturing | 2014 |
| Spice Indian Cuisine Ltd | Hospitality | 2024 |
| Spie Wind Connect Ltd | Administrative & support | 2014 |
| ST Peter's Centre CIC | Other services | 2020 |
| ST Renewables Ltd | Administrative & support | 2016 |
| Staines Safety Services Ltd | Information & communication | 2017 |
| Staithes Communities Ltd | Health & social care | 2006 |
| Stanghow Hall Ltd | Hospitality | 2021 |
| Starlie Business Support Ltd | Professional & scientific | 2024 |
| Starline Construction Limited | Construction | 2018 |
| Starline Holdings NE Ltd | Financial services | 2025 |
| Stay Local (NE) Limited | Administrative & support | 2023 |
| Stemset Ltd | Professional & scientific | 2017 |
| Stephen Savage Ltd | Manufacturing | 2022 |
| Sterne Cottages Management Company Limited | Households | 2005 |
| Stone Circle Estates Ltd | Real estate | 2022 |
| Stonehouse Bakery Limited | Manufacturing | 2002 |
| Stonehouse Safety & Performance Ltd | Professional & scientific | 2026 |
| Straight UP Solutions Ltd | Administrative & support | 2024 |
| Stuart Fletcher Ltd | Wholesale & retail | 2023 |
| Support Squad 365 Ltd | Administrative & support | 2024 |
| Swales Builders Limited | Construction | 2024 |
| Synthetic Turf Maintenance Ltd | Administrative & support | 2019 |
| Synthetic Turf Management Limited | Administrative & support | 2009 |
| T Dart Ltd | Professional & scientific | 2016 |
| T R Gardening Services Ltd | Administrative & support | 2018 |
| T.S. & L. Petch Ltd | Agriculture & fishing | 2022 |
| Tabner Engineering Installations Ltd | Manufacturing | 2026 |
| TAD Web Solutions Limited | Information & communication | 2011 |
| TAG Ecom Ltd | Wholesale & retail | 2024 |
| Taste of China (Brotton) Ltd | Hospitality | 2013 |
| TC Advanced Auto Diagnostics and Repairs Ltd | Wholesale & retail | 2025 |
| TC Industries of Europe Limited | Manufacturing | 1984 |
| TEAL33 Ltd | Hospitality | 2023 |
| Tecshop Ltd | Wholesale & retail | 2016 |
| Tees Components Brass Limited | Arts & recreation | 2025 |
| Tees Valley Property Services Ltd | Professional & scientific | 2005 |
| Tees Valley Tooling Ltd | Wholesale & retail | 2020 |
| Tees-Valley Care Limited | Health & social care | 2017 |
| Teesec Ltd | Construction | 2016 |
| Teesside Trading Ltd | Wholesale & retail | 2023 |
| TELEDESIGN2013 Limited | Professional & scientific | 2013 |
| Temptake Limited | Information & communication | 2025 |
| Terrain Trading UK Ltd | Professional & scientific | 2022 |
| Thai Sea Ltd | Hospitality | 2018 |
| THE Arches Cookery School Limited | Education | 2009 |
| THE Cleveland Retreat Limited | Hospitality | 2020 |
| THE DRY Knickers Project CIC | Health & social care | 2025 |
| THE Gables Management Company (Saltburn) Limited | Households | 2013 |
| THE Grouse Bar & Restaurant Limited | Hospitality | 2026 |
| THE Lillian Daph Store Ltd | Wholesale & retail | 2019 |
| THE Lingdale Tavern Ltd | Hospitality | 2024 |
| THE Little Spanish Cleaning Company Ltd | Wholesale & retail | 2020 |
| THE Loftus Fish & Chips Limited | Hospitality | 2026 |
| THE New Marine Hotel Ltd | Hospitality | 2011 |
| THE Nook Play Café Limited | Hospitality | 2025 |
| THE Nook Saltburn Ltd. | Hospitality | 2018 |
| THE Northern Lands Leather Ltd | Manufacturing | 2024 |
| THE People's Stage Theatre Group CIC | Education | 2026 |
| THE Protection Office Limited | Financial services | 2001 |
| THE Royal George (Staithes) Limited | Hospitality | 2011 |
| THE Seaview Restaurant Ltd | Hospitality | 2006 |
| THE Travelers Rest Limited | Hospitality | 2022 |
| THE Truffled HOG Saltburn Ltd | Hospitality | 2025 |
| THE W.H-I Corporation Ltd | Wholesale & retail | 2022 |
| THE Wonky Carrot Middlesbrough Ltd | Hospitality | 2018 |
| Thornbeck Design Limited | Professional & scientific | 2011 |
| Tillmont Consulting Limited | Financial services | 2024 |
| TJW Products Limited | Wholesale & retail | 2023 |
| TOM Affleck Ltd | Construction | 2018 |
| Townend Farm (Easington) Management Company Limited | Professional & scientific | 2012 |
| TR Developments Limited | Real estate | 2006 |
| Traditional Beams Holdings Ltd | Financial services | 2026 |
| Traditional Beams Investments Ltd | Real estate | 2026 |
| Traditional Beams Ltd | Manufacturing | 2015 |
| Transforming Transition. Ltd. | Professional & scientific | 2012 |
| Transonic Limited | Transport & logistics | 1998 |
| TRG Construction Plant Limited | Construction | 2025 |
| TS12 Motors Ltd | Wholesale & retail | 2020 |
| Tssw Limited | Construction | 2024 |
| Ttrrl Ltd | Arts & recreation | 2021 |
| TTS Hospitality Ltd | Hospitality | 2024 |
| Turner Management and Consultancy Ltd | Real estate | 2019 |
| Turner Street Developments Ltd | Real estate | 2006 |
| Tusker Trading Limited | Financial services | 2015 |
| TVC (NE) Ltd | Wholesale & retail | 2019 |
| Twentytwo Coastal Retreats Limited | Real estate | 2025 |
| Twinkle Star Baby Ltd | Wholesale & retail | 2022 |
| Twinson Leisure Ltd | Real estate | 2021 |