| Synergy Systems Limited | Information & communication | 1986 |
| Synexeos Ltd | Information & communication | 2020 |
| Syntarchis Ltd | Professional & scientific | 2020 |
| System Design Consulting Ltd | Professional & scientific | 2012 |
| Systems Critical Thinking Ltd | Information & communication | 2025 |
| Sytecourt Limited | Administrative & support | 2001 |
| T H T Ltd | Construction | 2011 |
| T&Lm Ltd | Real estate | 2025 |
| T&W Creations Ltd | Arts & recreation | 2025 |
| T-Fit Inc Ltd | Other services | 2009 |
| T.R.B. Construction Ltd. | Wholesale & retail | 1996 |
| T.T.P. Perspectives Ltd | Professional & scientific | 2025 |
| T3DM Limited | Households | 2021 |
| T4 Associates Ltd | Extraterritorial | 2014 |
| Taam Properties Limited | Real estate | 2017 |
| TAB Financial Planning Limited | Professional & scientific | 2023 |
| Tack Locker Limited | Wholesale & retail | 2025 |
| Tackle TAP Ltd | Administrative & support | 2025 |
| Tactica Limited | Professional & scientific | 2010 |
| Tahoe Consultants Limited | Professional & scientific | 2025 |
| Tail File UK Ltd | Manufacturing | 2023 |
| Tailor Contros Ltd | Professional & scientific | 2019 |
| Take Wing Consulting Limited | Professional & scientific | 2019 |
| Takeoff Training & Consultancy Ltd | Professional & scientific | 2018 |
| Tako Services Ltd | Professional & scientific | 2025 |
| Talbot Woods Wealth Management Ltd | Financial services | 2017 |
| Talent Evolution Ltd | Administrative & support | 2023 |
| Talk for Peace | Information & communication | 2010 |
| Talk Psychology (Services) Limited | Health & social care | 2025 |
| Tall TIM Residential Property Services Limited | Households | 2025 |
| Tallionus Ltd | Information & communication | 2015 |
| Talltimcommercial Property Ltd | Households | 2025 |
| Tanyard Timber Ltd | Manufacturing | 2023 |
| Tarboosh Limited | Information & communication | 2001 |
| Tarrant Engineering Limited | Manufacturing | 2006 |
| Taskforce Research Limited | Information & communication | 2001 |
| Tasty Apps Ltd | Information & communication | 2026 |
| Tasty Treat MB Private Ltd | Hospitality | 2026 |
| Taurus Flooring (Hampshire) Limited | Construction | 2011 |
| Tavistock Care Limited | Education | 2001 |
| Tavuk Grill Ltd | Hospitality | 2025 |
| Tax Innovations Limited | Professional & scientific | 1995 |
| Taylor Corporate Solutions Limited | Professional & scientific | 2020 |
| Taylor Fordyce Limited | Professional & scientific | 2007 |
| Taylor Power Group Limited | Professional & scientific | 2016 |
| Taylor Power International Limited | Manufacturing | 2023 |
| Taylor Power Limited | Professional & scientific | 2015 |
| Taylor Tripp Hampshire Limited | Professional & scientific | 2026 |
| Taylor Tripp Ltd. | Professional & scientific | 1995 |
| Taylored Advice Group Limited | Professional & scientific | 2020 |
| Taylored Group Holdings Ltd | Financial services | 2016 |
| Tazros Limited | Professional & scientific | 2021 |
| TBC Winchester Limited | Other services | 2025 |
| TCG Arcade Ltd | Wholesale & retail | 2026 |
| TDI Buildings Limited | Construction | 2020 |
| TDI Pro AV Ltd | Wholesale & retail | 2024 |
| TDI Tremiver Ltd. | Wholesale & retail | 1979 |
| TDM 2013 Ltd | Financial services | 2013 |
| Teach the Teachers Ltd | Education | 2025 |
| Technicality Limited | Professional & scientific | 2012 |
| Technology Boutique Limited | Administrative & support | 2015 |
| Technology Investment Services Ltd | Professional & scientific | 2024 |
| TECHNOLOGY4BUSINESS Ltd | Wholesale & retail | 2019 |
| Techüman Limited | Manufacturing | 2023 |
| Teckno & Gadgets Limited | Wholesale & retail | 2025 |
| Teiars HUW Lewis CYF | Professional & scientific | 2004 |
| Telecx Ltd | Information & communication | 2019 |
| Tellett Films Limited | Information & communication | 2014 |
| Tempest Hilary Limited | Professional & scientific | 2003 |
| Temple Asset Group Ltd | Hospitality | 2025 |
| Temple Asset Investments Ltd | Financial services | 2025 |
| Temple Construction Company Limited | Construction | 2023 |
| Temple Valley Sporting Ltd | Arts & recreation | 2015 |
| TEN Tenths Accountancy Ltd | Professional & scientific | 2003 |
| Tend Limited | Professional & scientific | 2014 |
| Tenfore Systems UK Limited | Agriculture & fishing | 1999 |
| Tent and Trail Ltd | Wholesale & retail | 2020 |
| Tentplanner Limited | Information & communication | 2019 |
| Terri Stromeyer Psychic Medium Limited | Other services | 2013 |
| Tesoro Group Global (TGG) Ltd | Wholesale & retail | 2026 |
| Test Valley Business Park Management Company Limited | Real estate | 2023 |
| Test Valley Construction Ltd | Construction | 2019 |
| Test-Rite (UK) Ltd. | Administrative & support | 2009 |
| Testquest Limited | Agriculture & fishing | 1989 |
| TEX Solutions Limited | Information & communication | 2003 |
| Texsong (Winchester) Ltd | Hospitality | 2023 |
| TF Diagnostics Limited | Wholesale & retail | 2025 |
| TF Sharpe Consulting Ltd | Professional & scientific | 2018 |
| TH4CONSTRUCTION Ltd | Construction | 2019 |
| Thames Translations Limited | | 1972 |
| THE Academy of Arts Limited | Arts & recreation | 2012 |
| THE Accountant Next Door Ltd | Professional & scientific | 2024 |
| THE Amati Partnership LLP | | 2004 |
| THE ARK After School Club | Education | 2005 |
| THE Armada Court Management Company Limited | Households | 1987 |
| THE Ashmore Shoot Limited | Agriculture & fishing | 2008 |
| THE Atelier Manco Ltd | Households | 2026 |
| THE Autism Wellness Collective CIC | Education | 2023 |
| THE Barns at Church Farm Limited | Households | 2024 |
| THE Beeches (Winchester) Management Limited | Households | 2009 |