| THE Olive Sanctuary Limited | Other services | 2021 |
| THE Pamper Lounge Uckfield Ltd | Arts & recreation | 2022 |
| THE Prospect Development Company (UK) Ltd | Administrative & support | 2016 |
| THE Quint Essence LAB Ltd | Wholesale & retail | 2019 |
| THE Remarkable Mind Limited | Health & social care | 2025 |
| THE Ringles Cross Ltd | Hospitality | 2025 |
| THE Sussex Grind Ltd | Hospitality | 2023 |
| THE Sussex Hamper Company Ltd | Wholesale & retail | 2023 |
| THE Sussex Kitchen Ices Limited | Manufacturing | 2017 |
| THE Sussex Landlord Limited | Real estate | 2017 |
| THE Thomas Scanlan Trust | Health & social care | 2014 |
| THE Tiny Box Company Limited | Wholesale & retail | 2007 |
| THE Warminster Jeweller Ltd | Wholesale & retail | 2007 |
| THE Wealden Kitchen Limited | Hospitality | 2016 |
| THE Wise Finance Company Limited | Financial services | 1988 |
| THE Witch's in Ltd | Wholesale & retail | 2023 |
| THE Wolf Organization Ltd | Financial services | 2022 |
| THE Worst Girl Gang Ever Ltd | Wholesale & retail | 2021 |
| Themcs Ltd | Wholesale & retail | 2025 |
| Thesocialshift Ltd | Professional & scientific | 2024 |
| Thoroughbred Property Maintenance Limited | Construction | 2004 |
| Three Lions Scaffolding Limited | Construction | 2012 |
| Three Sheds Limited | Professional & scientific | 2025 |
| Threesix Fast Ltd | Wholesale & retail | 2018 |
| Tidewater Property Limited | Real estate | 1999 |
| Tiferet LLP | | 2019 |
| Tiffany Wardle Ltd | Information & communication | 2024 |
| Timberdown Management Company Limited | Real estate | 2001 |
| Time Health Ltd | Wholesale & retail | 2016 |
| Timi Exchange Ltd | Professional & scientific | 2013 |
| Timmspropertyinvestments Limited | Hospitality | 2025 |
| Tiny Box Maker Limited | Manufacturing | 2016 |
| Tiny Gang Limited | Other services | 2007 |
| Tiny Marketplace Ltd. | Wholesale & retail | 2020 |
| Tips and Toes Uckfield Limited | Other services | 2025 |
| Titan Landscape Ltd | Professional & scientific | 2018 |
| Titus Films Ltd | Information & communication | 2000 |
| TN34 001 Ltd | Real estate | 2023 |
| Todo Bien Consulting Limited | Professional & scientific | 2025 |
| Toga Flight Training Ltd | Transport & logistics | 2023 |
| TOM Lake Landscaping Ltd | Professional & scientific | 2022 |
| TOM Trade Ltd | Wholesale & retail | 2020 |
| Tommageo Limited | Wholesale & retail | 2021 |
| Toness Ltd | Professional & scientific | 2025 |
| Total Event Group Ltd | Administrative & support | 2020 |
| Total Performance Football Ltd | Education | 2025 |
| Trace AI Investigations Ltd | Administrative & support | 2025 |
| Trade Risk Resources Limited | Professional & scientific | 2021 |
| Tradewood Limited | Extraterritorial | 2001 |
| Tradewoods Limited | Wholesale & retail | 2001 |
| Traditional Homes (S.East) Limited | Real estate | 1997 |
| Trady IQ Ltd | Information & communication | 2026 |
| Trash Away Limited | Administrative & support | 1999 |
| Traverford Company Limited | Information & communication | 2024 |
| Travology Limited | Information & communication | 2002 |
| Treborp Limited | Real estate | 2026 |
| Trendency Digital Limited | Information & communication | 2012 |
| Tressler Holdings Limited | Financial services | 2023 |
| Tressler Trailers Coachwork Limited | Wholesale & retail | 1964 |
| Trevor Powell Accountancy Limited | Professional & scientific | 2005 |
| TRI Group Holdings Limited | Professional & scientific | 2009 |
| Triage Branding Ltd | Professional & scientific | 2025 |
| Trident Aquatics Limited | Agriculture & fishing | 2024 |
| Triple R Engineering Limited | Administrative & support | 1991 |
| Trongo Ltd | Wholesale & retail | 2012 |
| Turners Removals Limited | Professional & scientific | 2000 |
| Turnkey Aftercare Ltd | Construction | 2025 |
| Tursiops Trading Limited | Wholesale & retail | 1994 |
| TWA - the Work App Ltd | Information & communication | 2021 |
| Two J'S Holdings Limited | Financial services | 2024 |
| Two J'S Metalwork Limited | Manufacturing | 2020 |
| Tworld Digital Ltd | Manufacturing | 2015 |
| Tyler's Yard Management Company Limited | Households | 2009 |
| Tylers Limited | Wholesale & retail | 1997 |
| Uckfield and District Preservation Society Ltd | Arts & recreation | 2002 |
| Uckfield Bonfire and Carnival Society C.I.C. | Arts & recreation | 1997 |
| Uckfield Catering Ltd | Hospitality | 2026 |
| Uckfield CUT Ltd | Other services | 2026 |
| Uckfield District Taxis Ltd | Transport & logistics | 2024 |
| Uckfield Food and Wine Ltd | Wholesale & retail | 2025 |
| Uckfield Framing Company Ltd | Manufacturing | 1997 |
| Uckfield Garage Ltd | Wholesale & retail | 2019 |
| Uckfield Health Store Ltd | Wholesale & retail | 2026 |
| Uckfield Ltd | Hospitality | 2023 |
| Uckfield Model Railway Club Limited | Arts & recreation | 1999 |
| Uckfield Nail Bar Limited | Other services | 2022 |
| Uckfield Rugby Football Club Limited | Arts & recreation | 2009 |
| Udoor Ltd | Construction | 2018 |
| Udps Heritage Ltd | Wholesale & retail | 2007 |
| UK Growth Coach Franchise Limited | Professional & scientific | 2024 |
| UK Growth Coach Limited | Professional & scientific | 2019 |
| Umcmc Ltd | Administrative & support | 2014 |
| Underwood Motor Company Limited | Wholesale & retail | 2024 |
| Unicorn Network Ltd | Professional & scientific | 2026 |
| Unimotive Group Ltd | Wholesale & retail | 2026 |
| United Kingdom Association for Transactional Analysis | Other services | 1997 |
| Universal Dance Limited | Arts & recreation | 2015 |
| Universal Quality Exports Limited | Wholesale & retail | 2016 |
| Unlimited Possibilities Ltd | Construction | 2015 |
| Upixa Ltd | Information & communication | 2009 |