| Tuckers Plant Services Limited | Extraterritorial | 2021 |
| Tudor Court Residents (Eastbourne) Limited | Households | 2007 |
| Tudor Homes South East Limited | Real estate | 2021 |
| Tuey Ltd | Information & communication | 2022 |
| Tuff-Trek Ltd | Wholesale & retail | 2013 |
| Tumble Wells Limited | Wholesale & retail | 2025 |
| Turboworks Ltd | Wholesale & retail | 2014 |
| Turkish Villas Limited | Hospitality | 2012 |
| Turner Carpentry Contractors Limited | Construction | 2003 |
| Turnham Limited | Professional & scientific | 1999 |
| TUW Films Limited | Administrative & support | 2017 |
| TVM Investments Limited | Real estate | 2017 |
| TVS Prestige Limited | Wholesale & retail | 2014 |
| TVT Holdings Limited | Extraterritorial | 2015 |
| TVX Optical Limited | Health & social care | 2016 |
| TW Energy Ltd | Financial services | 2016 |
| TW Management Holdings Ltd | Financial services | 2025 |
| Twenty SIX Grange Road Limited | Households | 1994 |
| Twenty SIX Weeks Ltd | Professional & scientific | 2017 |
| Twinbrook Windows Limited | Construction | 2002 |
| Twisted Willow Clothing Limited | Wholesale & retail | 2016 |
| TWM Management Ltd | Real estate | 2023 |
| Two Goons Media Limited | Arts & recreation | 2012 |
| Two Pens Ltd | Professional & scientific | 2019 |
| Two Plus One Windscreens Limited | Wholesale & retail | 2002 |
| Two Trees Cafe Limited | Extraterritorial | 2014 |
| Twohippo Ltd | Professional & scientific | 2025 |
| Twortattack Ltd | Wholesale & retail | 2026 |
| Twyford Chiropractic Clinic Limited | Health & social care | 2022 |
| TY Creations Ltd | Manufacturing | 2024 |
| Tyeson Ltd | Real estate | 2026 |
| TYP Limited | Extraterritorial | 2009 |
| U2M Audio Limited | Administrative & support | 2007 |
| UBI Investments Limited | Real estate | 2025 |
| Ubiquicore Limited | Information & communication | 2016 |
| Ubiquitous Health Ltd | Health & social care | 2013 |
| Uckfield Motor Services Limited | Wholesale & retail | 2019 |
| Uheba Medical Services Ltd | Health & social care | 2017 |
| Ujhi Ltd | Health & social care | 2013 |
| UK Action Cars Ltd | Wholesale & retail | 2005 |
| UK Diving Services Ltd | Administrative & support | 2013 |
| UK Europe Property Investments Ltd | Real estate | 2024 |
| UK Hotels Ltd | Real estate | 2022 |
| UK Print Products Limited | Extraterritorial | 1992 |
| UK Ravens Limited | Other services | 2026 |
| UK Tax Group Ltd | Administrative & support | 2024 |
| UK Ultra Ltd | Arts & recreation | 2020 |
| UK Wristbands Ltd | Manufacturing | 2013 |
| Ukai Ltd | Other services | 2019 |
| Ukfl Ltd | Wholesale & retail | 2019 |
| Ultimate 888 Ltd | Real estate | 2020 |
| Ultimate Coaching Limited | Education | 2013 |
| Ultimate Football Academy Ltd | Education | 2023 |
| Ultimate Football Consultancy Ltd | Education | 2018 |
| Ultimate Renovation Limited | Construction | 2022 |
| Ultra TCG Ltd | Wholesale & retail | 2025 |
| Ultramark Limited | Transport & logistics | 1980 |
| Umoks Ltd | Administrative & support | 2012 |
| UMS Commercial Properties Limited | Real estate | 2026 |
| UMS Properties Sussex Limited | Real estate | 2022 |
| Umzii Ltd | Wholesale & retail | 2024 |
| Unbarred Project CIC | Education | 2026 |
| Underdown & Co Limited | Professional & scientific | 1999 |
| Underhill Meadow (Maresfield) Limited | Households | 2022 |
| Unfys Consulting Ltd | Information & communication | 2023 |
| Unibrook Developers Ltd | Real estate | 2007 |
| Unibrook Estates Limited | Real estate | 2003 |
| Unibrook Properties Limited | Real estate | 2006 |
| Unicross Estates Limited | Wholesale & retail | 1999 |
| Unicus Building Solutions Limited | Construction | 2021 |
| Unified Events Group Limited | Administrative & support | 2025 |
| Unigel Group Limited | Financial services | 2022 |
| Unigel Limited | Administrative & support | 2016 |
| Unipharma Holding Ltd | Administrative & support | 2018 |
| Unique Smiles Limited | Health & social care | 2018 |
| Unitape Limited | Manufacturing | 2000 |
| United Builders UK Limited | Construction | 2003 |
| United Drylining (South East) Limited | Construction | 2014 |
| United Property Solutions Ltd | Real estate | 2019 |
| Universal Umvelt Ltd | Professional & scientific | 2011 |
| Universalstudy.Co.Uk Limited | Education | 2010 |
| Unlock Property Solutions Limited | Real estate | 2017 |
| Unodor Ltd | Information & communication | 2015 |
| Unstable Productions UK Limited | Information & communication | 2024 |
| Unstable Services Ltd | Administrative & support | 2021 |
| Unty Hair Ltd | Other services | 2026 |
| Unusual Suspectz CIC | Education | 2021 |
| UP Acre Ltd | Information & communication | 2022 |
| Upepo Ltd | Real estate | 2020 |
| Upfields Complete Bathrooms Limited | Construction | 1995 |
| Uphillot Ltd | Health & social care | 2026 |
| Upperton Estates Limited | Households | 2009 |
| Upperton Mortgage Advice Limited | Financial services | 2022 |
| Uproot Ltd | Health & social care | 2025 |
| Uprove Limited | Information & communication | 2006 |
| Upskill People Limited | Administrative & support | 2003 |
| Uptons Properties Ltd | Real estate | 2025 |
| Upwick Mews Management Company Limited | Households | 2016 |
| Urban Creep Ltd | Administrative & support | 2017 |
| Urban Ground Limited | Hospitality | 2006 |