| Tulsi Convenience Store Ltd | Wholesale & retail | 2026 |
| Tumpe Limited Company Ltd | Health & social care | 2022 |
| Tunari Drive Ltd | Transport & logistics | 2024 |
| Tunesline Limited | Arts & recreation | 2022 |
| Turay Limited | Construction | 2013 |
| Turbo Hire Ltd | Transport & logistics | 2025 |
| Turbo Service International Holdings Limited | Manufacturing | 2012 |
| Turbo Services International Limited | Manufacturing | 2022 |
| Turbo Speedition Limited | Transport & logistics | 2025 |
| Turbo Talents Ltd | Administrative & support | 2024 |
| Turkish Barber Southampton Ltd | Other services | 2024 |
| Turkish Hair Style Barbers Ltd | Other services | 2018 |
| Turkish Style Shirley Ltd | Other services | 2025 |
| Turkish Table Limited | Hospitality | 2024 |
| Turnberry Group Ltd | Construction | 2025 |
| Turnbull Group Ventures Limited | Other services | 2023 |
| Turner & COE Consulting Ltd | Professional & scientific | 2025 |
| Turner & Tams Limited | Other services | 2023 |
| Turner Gladston LLP | | 2025 |
| Turner Property Lettings Ltd | Real estate | 2020 |
| Turning Point Events Ltd | Administrative & support | 2022 |
| Turning Spanners Ltd | Wholesale & retail | 2020 |
| Turtle Finance Limited | Financial services | 2003 |
| Turtle Straws Ltd | Wholesale & retail | 2018 |
| Turtle Tots Southampton Ltd | Education | 2025 |
| Tuscan Red Investments Ltd | Financial services | 2017 |
| Tushil Private Ltd | Wholesale & retail | 2019 |
| Tutd Limited | Real estate | 2008 |
| Tutis Property Ltd | Real estate | 2016 |
| Tutoring Direct Limited | Education | 2016 |
| Tutto Passa Holdings Ltd | Financial services | 2026 |
| Tuvaa CIC | Arts & recreation | 2024 |
| Tvilum UK Limited | Wholesale & retail | 1995 |
| TW Consultants International Limited | Administrative & support | 2023 |
| TW Tea Southampton Limited | Hospitality | 2024 |
| TW2000 Limited | Wholesale & retail | 1999 |
| TWB Alehouse Ltd | Hospitality | 2025 |
| TWC Bizadvice Ukeig | | 2008 |
| Tweed Media Ltd | Professional & scientific | 2010 |
| Tweezi Ltd | Information & communication | 2024 |
| Twelve Edge Limited | Wholesale & retail | 2025 |
| Twelve Endeavor Ltd | Wholesale & retail | 2019 |
| Twenty Eleven Events Ltd | Hospitality | 2022 |
| Twenty-Seven West Mall Management Company Limited | Households | 1976 |
| TWENTY5 Group Ltd | Construction | 2020 |
| TWENTY5JUNE Ltd | Construction | 2021 |
| TWENTY8 Three Ltd | Professional & scientific | 2015 |
| TWG Carpentry and Kitchens Ltd | Construction | 2023 |
| Twics (Training for Work in Communities) | Education | 1999 |
| Twiggs Lane Pre-School | Education | 2011 |
| Twin Oaks Property Management Limited | Households | 2016 |
| Twin Scissors Hairstyles Limited | Other services | 2021 |
| Twine Garden Services Limited | Administrative & support | 2026 |
| Twinhouse Limited | Information & communication | 2021 |
| Twiss Green Limited | Information & communication | 2014 |
| Two Pahadi 22 Limited | Hospitality | 2022 |
| Two Wheels Feels Limited | Professional & scientific | 2024 |
| Two's Company Group Ltd | Professional & scientific | 2025 |
| Twoj Sklep Foods Limited | Wholesale & retail | 2020 |
| Twotrucks Productions Ltd | Arts & recreation | 2018 |
| Twyford Human Resources Ltd. | Professional & scientific | 2012 |
| Tyam Tyres Ltd | Wholesale & retail | 2022 |
| Tycho Exploration Limited | Professional & scientific | 2019 |
| Tyersfishing Ltd | Agriculture & fishing | 2026 |
| Tyler Phillips Recruitment Limited | Administrative & support | 2021 |
| TYME4U Ltd | Other services | 2014 |
| TYME4U Trustees Limited | Other services | 2025 |
| Tyndale Care Ltd | Health & social care | 2016 |
| Tynwood Building Services Limited | Administrative & support | 2017 |
| Typhoon International Limited | Manufacturing | 1948 |
| Tyre END Ltd | Wholesale & retail | 2026 |
| Tyresales and Service (Hedge END) Limited | Wholesale & retail | 1981 |
| Tyreshops Hampshire Limited | Wholesale & retail | 2019 |
| TYY Barber Ltd | Other services | 2024 |
| Tzighi & Anka Ltd | Transport & logistics | 2017 |
| U Colab Studio Ltd | Other services | 2025 |
| U Ride Limited | Transport & logistics | 2024 |
| U SAT Autotech Ltd | Wholesale & retail | 2020 |
| U&I Care Direct Ltd | Health & social care | 2023 |
| U&J Enterprises Ltd | Wholesale & retail | 2025 |
| U-Nnovate UK Limited | Information & communication | 2021 |
| U.K. Scent Ltd | Wholesale & retail | 2022 |
| U4GLOBAL Solutions Limited | Wholesale & retail | 2000 |
| UA Carpentry Ltd | Construction | 2020 |
| UA Top Service Ltd | Administrative & support | 2021 |
| Uanu Ltd | Information & communication | 2025 |
| Uanu Properties Limited | Real estate | 2023 |
| UAV Flight Support Ltd | Professional & scientific | 2021 |
| Uaventerprise Limited | Information & communication | 2021 |
| Ubiq Medicines Limited | Extraterritorial | 2023 |
| Ubsoftware Ltd | Information & communication | 2026 |
| Ubuntu 52 Ltd | Construction | 2023 |
| Ubuntu Fashion Limited | Manufacturing | 2012 |
| Ubuntu STROKE360 Ltd | Health & social care | 2025 |
| UBUNTU54 Ltd | Information & communication | 2026 |
| UCR Holdings Ltd | Financial services | 2019 |
| UCR Integrations Ltd | Professional & scientific | 2020 |
| Ucug Limited | Hospitality | 2022 |
| UFG. Limited | Wholesale & retail | 2014 |
| Ugaine Developments Group Limited | Construction | 2025 |