| Terroir Tapas Ltd | Hospitality | 2017 |
| Tertius Energy Limited | Administrative & support | 2025 |
| Teslly Ltd | Information & communication | 2025 |
| Test Mill Romsey Limited | Households | 1999 |
| Test Valley Driveways Limited | Construction | 2022 |
| Test Valley Environmental Limited | Construction | 2003 |
| Test Valley Financial Management Limited | Financial services | 2005 |
| Testcraft Academy Ltd | Education | 2025 |
| Testlands Education & Learning Limited | Arts & recreation | 2011 |
| Testway Glazing Ltd | Construction | 2019 |
| Testwood Imaging Limited | Health & social care | 2021 |
| Testwood School | Education | 2011 |
| Tetra Ltd | Construction | 2021 |
| Tetra Networks Ltd | Information & communication | 2022 |
| Tetra PAK Moulded Packaging Systems Limited | Professional & scientific | 1990 |
| Tetrapod Zoology Ltd | Administrative & support | 2024 |
| Tett Construction Ltd | Construction | 2019 |
| TEW Brothers Holdings Limited | Financial services | 2023 |
| Texas Grill (Southampton) Ltd | Hospitality | 2016 |
| Texhide Ltd | Wholesale & retail | 2025 |
| TEY Chippy Ltd | Hospitality | 2026 |
| TF.UK2026 Limited | Hospitality | 2026 |
| TFJ Mortgages Limited | Administrative & support | 2017 |
| Tfly Limited | Manufacturing | 2008 |
| TFR Delivery Ltd | Transport & logistics | 2026 |
| TFR Media Ltd | Administrative & support | 2015 |
| TG Marine Plumbing Solutions Ltd | Construction | 2024 |
| TGB Market Trading Ltd | Financial services | 2025 |
| Tgbas Consultancy Limited | Administrative & support | 2017 |
| TGH Contractors Limited | Construction | 2009 |
| TGM Dental Care Limited | Health & social care | 2014 |
| TH Coffee Ltd | Hospitality | 2026 |
| TH Digital Limited | Administrative & support | 2011 |
| TH Global Trading Ltd | Wholesale & retail | 2026 |
| TH Installations Ltd | Construction | 2023 |
| TH Scott Ltd | Wholesale & retail | 2024 |
| Thaiuk Ltd | Wholesale & retail | 2019 |
| Thakkar Properties Limited | Real estate | 2021 |
| Thames Valley Interiors Limited | Construction | 1997 |
| Thapliyal Enterprise Ltd | Information & communication | 2026 |
| Thatcher View Development Limited | Real estate | 2015 |
| THB Plumbing & Heating Ltd | Construction | 2024 |
| THC Highfield Limited | Administrative & support | 2020 |
| THE 1 Rhino Ltd | Education | 2023 |
| THE 12 Ashburnham Close Management Company Limited | Real estate | 2023 |
| THE 247 Giant Limited | Other services | 2019 |
| THE 384 Hill Lane Management Company Limited | Households | 2004 |
| THE 3R Group Limited | Financial services | 2023 |
| THE 9809 Store Limited | Wholesale & retail | 2024 |
| THE Abbotts Store Ltd | Wholesale & retail | 2024 |
| THE Academy for Professional Intelligence Ltd | Education | 2023 |
| THE Accounting Studio Digital Limited | Professional & scientific | 2017 |
| THE Accounting Studio Limited | Professional & scientific | 2021 |
| THE Acute Care Partnership LLP | | 2011 |
| THE Adams Trading Company Ltd | Wholesale & retail | 2023 |
| THE Admin Hive Limited | Administrative & support | 2025 |
| THE Administ & Co Limited | Administrative & support | 2024 |
| THE Adventure Experience Limited | Arts & recreation | 2010 |
| THE Afghan Care Partnership LLP | | 2015 |
| THE Agile Leader Ltd | Information & communication | 2017 |
| THE Air Conditioning Showroom Limited | Energy | 2010 |
| THE Alex Southampton Ltd | Hospitality | 2023 |
| THE Alma House Management Company Limited | Households | 1993 |
| THE American HUT Limited | Wholesale & retail | 2024 |
| THE Anchorage Property Company Limited | Real estate | 2020 |
| THE Appleton Company Holdings Ltd | Financial services | 2022 |
| THE Aranea Company Limited | Wholesale & retail | 2011 |
| THE Archers Southampton Limited | Hospitality | 2026 |
| THE ARK Financial Management Consultancy Ltd | Professional & scientific | 2024 |
| THE Art House Southampton Community Interest Company | Hospitality | 2008 |
| THE Art Movement Limited | Administrative & support | 2008 |
| THE Artisan Floral Studio Ltd | Wholesale & retail | 2020 |
| THE Artistic Hearts Ltd | Arts & recreation | 2025 |
| THE Association of Sail Training Organisations | Other services | 2000 |
| THE Atherley Bowls and Social Club Limited | Arts & recreation | 2024 |
| THE Atlantic (BD) Ltd | Hospitality | 2026 |
| THE Authentic Kitchen (Southampton) Ltd | Manufacturing | 2024 |
| THE Avenues Group Limited | Real estate | 2017 |
| THE Awesome Adventure Co Ltd | Administrative & support | 2020 |
| THE Baggage Handling Company Limited | Transport & logistics | 2009 |
| THE Baggery Sundries UK Limited | Wholesale & retail | 2020 |
| THE Balanced Rider Limited | Health & social care | 2015 |
| THE Barbell Division Limited | Health & social care | 2018 |
| THE Barber Sanctuary Ltd | Other services | 2019 |
| THE Barker Corporation Limited | Administrative & support | 2015 |
| THE Barns (Winterslow) Ltd | Real estate | 2022 |
| THE Barton Bar Company Limited | Wholesale & retail | 2019 |
| THE Bath Concierge Limited | Other services | 2019 |
| THE Bathroom and Kitchen Academy Limited | Wholesale & retail | 2018 |
| THE Battersea Brewery Company Limited | Manufacturing | 2000 |
| THE Battery Recycling Company Ltd | Water & waste | 2022 |
| THE Beacham Collective Limited | Financial services | 2025 |
| THE Beaulieu Candle Company Ltd | Manufacturing | 2019 |
| THE Beauty Bistro Ltd | Wholesale & retail | 2022 |
| THE Beauty Edit Limited | Other services | 2023 |
| THE Beauty Lounge South Ltd | Other services | 2023 |
| THE Beehive Enterprise Ltd | Hospitality | 2020 |
| THE Beer Authority Limited | Professional & scientific | 2016 |
| THE Bell Inn ST Nicholas Limited | Other services | 2019 |
| THE Benson PUB Co Ltd | Hospitality | 2025 |