| Topic Hero Ltd. | Information & communication | 2025 |
| Total Assistance Electrical Limited | Construction | 2023 |
| Total Vehicle Services Limited | Wholesale & retail | 2012 |
| Total Vida Ltd | Health & social care | 2025 |
| Tots 2 Teens Childrens Daycare Ltd | Health & social care | 2022 |
| Tourific Limited | Transport & logistics | 2023 |
| Towards the Danger Holdings Limited | Administrative & support | 2025 |
| Towards the Danger Ltd | Wholesale & retail | 2025 |
| Tower Classics Ltd | Wholesale & retail | 2024 |
| Toy Heaven for Children Limited | Wholesale & retail | 2021 |
| TP1 Golf Ltd | Professional & scientific | 2025 |
| TPT Health & Fitness Ltd | Arts & recreation | 2020 |
| TPT Investments Ltd | Financial services | 2025 |
| TR Hire Ltd | Transport & logistics | 2017 |
| Trader SIP Solutions Ltd | Real estate | 2015 |
| Trading System Support Ltd | Administrative & support | 2013 |
| Trakkapro Ltd | Wholesale & retail | 2025 |
| Tranquillity Beauty & Spa Limited | Other services | 2006 |
| Transformers Agency Limited | Information & communication | 2024 |
| Transport Advisory Consultants Limited | Professional & scientific | 2002 |
| Travel Views UK Limited | Information & communication | 2002 |
| Travel With Gary Ltd | Administrative & support | 2016 |
| Tredwell Property Management Limited | Real estate | 2006 |
| Tremain Talent Limited | Professional & scientific | 2017 |
| Trends Renewal Ltd | Wholesale & retail | 2024 |
| Tresmont Hane Management Ltd | Real estate | 2025 |
| Tresmont Hane SA Ltd | Real estate | 2024 |
| Trew Consultancy Services Ltd | Construction | 2024 |
| Trew Landscapes & Groundworks Limited | Construction | 2017 |
| Trez Entertainment Ltd | Professional & scientific | 2019 |
| Trichology by Tiffany Hall Ltd | Other services | 2023 |
| Trimech MEP Ltd | Construction | 2023 |
| Triple a Property Limited | Real estate | 2024 |
| Tritec Building Contractors Ltd | Construction | 2014 |
| Triunity Ltd | Administrative & support | 2020 |
| Trojan Transactions Ltd | Professional & scientific | 2025 |
| Tropicana Nights Ltd | Arts & recreation | 2014 |
| Trouble Tongues CIC | Education | 2019 |
| Trudy's Architectural Consultants Ltd | Professional & scientific | 2014 |
| True Accountability Limited | Administrative & support | 2015 |
| True-Blue Investments Limited | Real estate | 2017 |
| Truedge Fitness Limited | Wholesale & retail | 2014 |
| Tshiama (London) Limited | Wholesale & retail | 2020 |
| Ttmc Limited | Administrative & support | 2011 |
| Tubetek Scaffolding Ltd | Construction | 2025 |
| Tudno Trading Ltd | Professional & scientific | 2023 |
| Tudor Lofts Ltd | Manufacturing | 2025 |
| Tuffenough Ltd | Wholesale & retail | 2015 |
| TUN UP Limited | Administrative & support | 2020 |
| TVB Limited | Wholesale & retail | 2023 |
| Twenty Five 8 Ltd | Professional & scientific | 2025 |
| TWENTYFOUR7 Stop Ltd | Manufacturing | 2023 |
| Twinserv Ltd | Information & communication | 2026 |
| Two One Zero Ltd | Professional & scientific | 2007 |
| Two Shots Coffee Services Limited | Manufacturing | 2022 |
| Tydas CLO Ltd | Wholesale & retail | 2024 |
| U Consults Limited | Hospitality | 2009 |
| U.P.E Services Ltd | Administrative & support | 2017 |
| UK Antiques Ltd | Wholesale & retail | 2023 |
| UK Business Innovation Group Ltd | Professional & scientific | 2023 |
| UK Lift & Haul Limited | Transport & logistics | 2004 |
| UK Lift & Haulage Limited | Administrative & support | 2008 |
| UK Overseas Culture and Education Association | Education | 2018 |
| UK Skips Limited | Water & waste | 2015 |
| UK Stairparts Limited | Manufacturing | 2002 |
| Ultimate Artificial Lawns Ltd | Wholesale & retail | 2022 |
| Ultimate Kelmscott Limited | Manufacturing | 1998 |
| Ultimateeventchildcare Ltd | Health & social care | 2019 |
| Ultra Tree Services Ltd | Agriculture & fishing | 2022 |
| Ultradigitaltv Ltd | Information & communication | 2016 |
| Umair Malik Limited | Information & communication | 2015 |
| Umitalla Holdings Limited | Real estate | 2024 |
| Unbiased (Financial Advice) UK Limited | Financial services | 2004 |
| Unit SIX Forty Four ST Pauls Crescent Ltd | Households | 2013 |
| Unitas Properties Ltd | Construction | 2024 |
| Unite Clean Ltd | Administrative & support | 2024 |
| United Artisans Ltd | Wholesale & retail | 2024 |
| Unity Court Management Company Limited | Households | 2000 |
| Unlimited Nutrition Ltd | Manufacturing | 2026 |
| Unlimited Pictures Limited | Information & communication | 2013 |
| Unlimited Property Limited | Real estate | 2016 |
| Untangled Code Ltd | Information & communication | 2024 |
| Unwired Creative Limited | Professional & scientific | 2019 |
| UOB KAY Hian (U.K.) Limited | Financial services | 1991 |
| Upbeat Lifestyle Limited | Health & social care | 2023 |
| Uptanhair Limited | Other services | 2025 |
| Upton Transport Ltd | Transport & logistics | 2026 |
| Urban Interior Solutions Ltd | Construction | 2004 |
| Ursel Limited | Construction | 2018 |
| US Confectionery Ltd | Wholesale & retail | 2024 |
| Utility Safety Solutions Limited | Professional & scientific | 2014 |
| V & G Company Ltd | Health & social care | 2017 |
| V & M Property Management Ltd | Real estate | 2018 |
| V J Services Limited | Professional & scientific | 1992 |
| V Nails & Spa 137 Ltd | Other services | 2025 |
| V.G. Bailey (Contractors) Limited | Construction | 2002 |
| V.S. Contractors UK Limited | Construction | 2008 |
| V10 Property Services Limited | Construction | 2023 |
| Valkyrie Financial Advice Ltd | Financial services | 2023 |
| Vanguard Auto Services Limited | Wholesale & retail | 2019 |