| Steel Darts Ltd | Wholesale & retail | 2025 |
| Steel River Fabrications Ltd | Construction | 2020 |
| Steel Rose Properties Ltd | Hospitality | 2022 |
| Stelis Direct Limited | Wholesale & retail | 2010 |
| Stepping UP in Teesside CIC | Hospitality | 2024 |
| Steven Flear CM Consultancy Ltd | Professional & scientific | 2025 |
| Steven Green Developments Limited | Real estate | 2015 |
| Stirling Finance Solutions Limited | Financial services | 2020 |
| Stnh Ltd | Professional & scientific | 2019 |
| Stokes Building Services Limited | Construction | 2026 |
| Strathern Opex Consulting Ltd | Professional & scientific | 2026 |
| Stuart Duckett Design Studio Limited | Professional & scientific | 2018 |
| Style Profiles Ltd | Wholesale & retail | 2011 |
| Suhki Dhami Properties Ltd | Real estate | 2022 |
| Summer Sound Events Ltd | Administrative & support | 2023 |
| Sunrock Realty LLP | | 2022 |
| Sunshine Day Nursery Limited | Health & social care | 2005 |
| Supre Agency Ltd | Information & communication | 2016 |
| Supre Comms Ltd | Information & communication | 2016 |
| Supre Group Ltd | Information & communication | 2016 |
| Supre Networks Ltd | Wholesale & retail | 2017 |
| Supre Software Ltd | Construction | 2008 |
| Supre WIT Ltd | Information & communication | 2016 |
| Supreme Surrounds Limited | Manufacturing | 2005 |
| Supremo’S Pizzeria Ltd | Hospitality | 2022 |
| Sussex Tool Truck Limited | Wholesale & retail | 2018 |
| Suwie Luxury Ltd | Wholesale & retail | 2025 |
| Suwie PRE Loved Ltd | Wholesale & retail | 2025 |
| SVO Energy Ltd | Mining & quarrying | 2026 |
| SVW Business Solutions Ltd | Professional & scientific | 2016 |
| SVW Convenience Ltd | Wholesale & retail | 2021 |
| Symbiosys Consulting Limited | Information & communication | 2013 |
| Synergy Training and Consultancy Limited | Other services | 2017 |
| Systemate Digital Ltd | Information & communication | 2025 |
| T and K Property Services Ltd | Hospitality | 2021 |
| T L Boffey Ltd | Manufacturing | 2026 |
| T. Joyce & Sons Limited | Construction | 2002 |
| Talk of the Town Magazine Ltd | Information & communication | 2023 |
| Talking Tides Brew Co Ltd | Manufacturing | 2021 |
| Talking Tides Hospitality Ltd | Hospitality | 2024 |
| Tanktainer Thurroclean (Middlesbrough) Limited | Administrative & support | 1997 |
| Tara Portman Limited | Wholesale & retail | 2021 |
| TAS (NE) Limited | Professional & scientific | 2012 |
| Taste of Bengal (AHS) Ltd | Hospitality | 2025 |
| Tatanka Holdings Limited | Financial services | 2023 |
| Tatanka Limited | Hospitality | 2020 |
| Tate Renewables Limited | Manufacturing | 2025 |
| Taylor Bickerstaff Logistics Ltd | Transport & logistics | 2025 |
| Tbrt (Global) Ltd | Manufacturing | 2022 |
| TC Trailers Ltd | Manufacturing | 2016 |
| TC Wind Renewables Ltd | Manufacturing | 2025 |
| Team Green Property Ltd | Real estate | 2019 |
| Tech Fixers Limited | Wholesale & retail | 2024 |
| Tech MTA Ltd | Wholesale & retail | 2019 |
| TED Harrison Building Services Ltd. | Construction | 2013 |
| Tees Consulting Ltd | Professional & scientific | 2024 |
| Tees Valley Arts | Education | 1982 |
| Tees Valley Bookkeeping Limited | Professional & scientific | 2023 |
| Tees Valley Community-Led Transport Ltd | Wholesale & retail | 2025 |
| Tees Valley Energy Recovery Limited | Water & waste | 2025 |
| Tees Valley Engineering Services Limited | Professional & scientific | 2017 |
| Teescore Inspection Services Limited | Professional & scientific | 2014 |
| Teesoutdoors CIC | Education | 2020 |
| Teesside Football Club Limited | Arts & recreation | 2025 |
| Teesside Law Limited | Professional & scientific | 2013 |
| Teesside Lettings Ltd | Real estate | 2020 |
| Teesside Mobile Aircon Ltd | Energy | 2026 |
| Teesside Property Group Ltd | Real estate | 2018 |
| Teesside Property N/E Ltd | Real estate | 2026 |
| Teesside Scaffold Design Solutions Ltd | Professional & scientific | 2020 |
| Teesstone (UK) Ltd | Other services | 2015 |
| Teesstone Group Ltd | Water & waste | 2018 |
| Teeswind Renewable Energy Ltd | Professional & scientific | 2023 |
| Tegridy Foods Ltd | Hospitality | 2020 |
| Telcoss Engineering Solutions Ltd | Professional & scientific | 2024 |
| Telcoss Group Holdings Ltd | Financial services | 2025 |
| Telcoss Integrated Services Ltd | Professional & scientific | 2026 |
| Telcoss Ltd | Professional & scientific | 2019 |
| Telcoss Technical Services Ltd | Professional & scientific | 2026 |
| Thai Good Limited | Hospitality | 2023 |
| THE Bespoke Catering Company Ltd | Hospitality | 2024 |
| THE Blindman (NE) Ltd | Construction | 2019 |
| THE Celebrity Gift Company Ltd | Other services | 2018 |
| THE Conscious Healing Coach Ltd | Health & social care | 2024 |
| THE Copper Quay Limited | Transport & logistics | 2023 |
| THE Craigs Group Ltd | Hospitality | 2018 |
| THE Dog House Marske Ltd | Hospitality | 2018 |
| THE Elite Barber Redcar Ltd | Other services | 2024 |
| THE Ethical Housing Company Limited | Real estate | 2017 |
| THE Ethical Housing Company Middlesbrough Limited | Real estate | 2021 |
| THE Ethical Lettings Agency CIC | Real estate | 2015 |
| THE Extra Engineer Ltd | Professional & scientific | 2022 |
| THE Faraday Centre Limited | Construction | 1993 |
| THE Grooming Shed Ltd | Wholesale & retail | 2021 |
| THE Hideout Group Ltd | Hospitality | 2026 |
| THE House of the Alchemist Limited | Hospitality | 2015 |
| THE Imaginarium Creative Studios Ltd | Education | 2019 |
| THE Industry Nature Conservation Association | Professional & scientific | 1989 |
| THE Junction Foundation | Education | 2008 |
| THE LH Group Holdings Limited | Administrative & support | 2016 |