| Teesside Ship Supplies Limited | Wholesale & retail | 2006 |
| Teesside Software Ltd | Information & communication | 2003 |
| Telmax Limited | Construction | 1997 |
| Temp Recruitment Ltd | Professional & scientific | 1999 |
| Tenndau Ltd | Wholesale & retail | 2025 |
| Teza Restaurant Limited | Hospitality | 2019 |
| THE Little Chip Ltd | Hospitality | 2007 |
| THE Priory Day Nursery Limited | Administrative & support | 2002 |
| Theakston Waller Limited | Real estate | 1974 |
| Therapy and Counselling Teesside Limited | Health & social care | 2004 |
| Thomas Foodmarket (1997) Limited | Wholesale & retail | 1996 |
| Thomas Foodmarket Limited | Wholesale & retail | 1962 |
| Thomas L.Bradley(Bishop Auckland)Limited | | 1955 |
| Thornaby Fabrications Limited | | 1974 |
| Toplira Limited | Hospitality | 1998 |
| Town & Village Homes Limited | | 1986 |
| Tradfab Limited | Manufacturing | 2000 |
| Triumph Press Limited | Manufacturing | 1963 |
| Trust Technology Limited | Extraterritorial | 2004 |
| TTT Building Services Limited | Construction | 2004 |
| Turner Street Garage Limited | Wholesale & retail | 2002 |
| Twed Consultancy Limited | Mining & quarrying | 2015 |
| Tyne Tees Entertainments Limited | Arts & recreation | 1984 |
| Universal Lift Systems Limited | Extraterritorial | 1994 |
| V J S Consultants Limited | Professional & scientific | 1986 |
| Veil Rich Dream PTY Ltd | | 2025 |
| Viso Partitions Limited | Construction | 2016 |
| W.A. Smith Insurance Brokers Limited | Financial services | 1951 |
| W.J.(Bill)Tillston Limited | Wholesale & retail | 1956 |
| Wagtails (NE) Ltd | Other services | 2003 |
| Walker E & I Services Ltd. | Professional & scientific | 2007 |
| Waterman Waste Management Limited | Water & waste | 1994 |
| Watson & Varley Properties Limited | Real estate | 2002 |
| Weldtech Fabrications Limited | Manufacturing | 2002 |
| Wellman Friction Products U.K. Corp. | | 1996 |
| West Hartlepool Masonic Hall Company Limited | Other services | 1891 |
| Whitfield Management Company Ltd | Real estate | 1997 |
| Williamsy Limited | Wholesale & retail | 2025 |
| Wilson Dunnakey Limited | | 1973 |
| Woodlands Cancer Care Limited | Other services | 1999 |
| Wright Hingley Limited | | 1945 |
| Wynyard Residential Company Ltd | Real estate | 2013 |
| Yarm Angling Limited | Arts & recreation | 2005 |
| Yarm Milk Deliveries Limited | Hospitality | 2011 |
| Your Home Solutions Limited | Real estate | 2007 |
| Zigi Enterprises Limited | Wholesale & retail | 1982 |