| T5 OIL & GAS Ltd | Mining & quarrying | 2013 |
| T5 OIL & GAS UK Limited | Mining & quarrying | 2013 |
| TA Impressions Ltd | Health & social care | 2025 |
| Tabaq Limited | Manufacturing | 2019 |
| Tabot and SON Limited | Health & social care | 2019 |
| Tacit Connexions Limited | Information & communication | 2003 |
| TAG Property Group Ltd | Real estate | 2021 |
| Taggy Developments Limited | Real estate | 2024 |
| Tagon Solutions Ltd | Information & communication | 2014 |
| Tait Architects Limited | Professional & scientific | 2011 |
| Takealytics Holdings Limited | Information & communication | 2025 |
| Takealytics Ltd | Information & communication | 2019 |
| Takeoff Consulting Corp LLP | | 2026 |
| Talacrest Limited | Wholesale & retail | 2014 |
| TALAIMANT360 Ltd | Professional & scientific | 2026 |
| Talansan Consulting Limited | Wholesale & retail | 2022 |
| Talensol PVT Ltd | Information & communication | 2024 |
| Talent Solutions Limited | Professional & scientific | 2009 |
| Talent Toute Ltd | Administrative & support | 2020 |
| TALENT34 Ltd | Administrative & support | 2025 |
| Talentbuff Ltd | Administrative & support | 2025 |
| Talihir Limited | Information & communication | 2025 |
| Talk Learning Limited | Professional & scientific | 2022 |
| Talliscan Ltd | Information & communication | 2012 |
| Tamara Services Ltd | Health & social care | 2024 |
| Tandes Consultant Limited | Construction | 2025 |
| Tanhouse Rentals Ltd | Real estate | 2025 |
| Tansark Ltd | Education | 2021 |
| Tansley Capital Limited | Real estate | 2023 |
| Tanton Brown Skin Clinic Limited | Other services | 2023 |
| Taplins LOO Hire Ltd | Administrative & support | 2026 |
| Tappen Homes Limited | Real estate | 2020 |
| Taptrade Ltd | Information & communication | 2026 |
| Tara Financial Services Ltd | Financial services | 1986 |
| Tara Sons Enterprises Ltd | Wholesale & retail | 2025 |
| Tara's Mobile Catering Limited | Hospitality | 2024 |
| Target Fastenings Limited | Wholesale & retail | 1986 |
| Tariqmuda Limited | Professional & scientific | 2012 |
| Task Consult Ltd | Information & communication | 2009 |
| Taste Natural Life Ltd | Hospitality | 2019 |
| Tavistock Mews (Barkham Road) Management Limited | Administrative & support | 2008 |
| Taxi Deauville Services Limited | Transport & logistics | 2016 |
| Taxi Finance Limited | Financial services | 2008 |
| Taycol Limited | Information & communication | 2008 |
| Taylor Made Landscape Design Limited | Administrative & support | 2015 |
| TBH Electrical Services Limited | Construction | 2017 |
| TBS Tools & Abrasives Limited | Wholesale & retail | 2004 |
| TCC Security Ltd | Construction | 2021 |
| Tcob Ltd | Administrative & support | 2001 |
| TDF Consulting Limited | Professional & scientific | 2018 |
| Tech Refreshed Limited | Information & communication | 2025 |
| Tech Savvy Income Ltd | Information & communication | 2023 |
| Tech Transpire Solutions Ltd | Information & communication | 2023 |
| Tech-Horizon Ltd | Information & communication | 2014 |
| TECH360PRO Ltd | Information & communication | 2014 |
| Techapps Consulting Ltd | Information & communication | 2016 |
| Techle Ltd | Information & communication | 2024 |
| Technotrend Limited | Manufacturing | 2003 |
| Tees Entertainment Ltd | Arts & recreation | 2025 |
| TEES2U Ltd | Wholesale & retail | 2024 |
| Tegh Ltd | Information & communication | 2013 |
| TEJ Estates Limited | Real estate | 2026 |
| TEJ Software Solutions Ltd | Information & communication | 2018 |
| Tekdynamics Ltd | Information & communication | 2022 |
| Tekwire Consulting Limited | Information & communication | 2026 |
| Tekyonics Ltd | Extraterritorial | 2021 |
| Telchines Limited | Professional & scientific | 2002 |
| Telephone Signallings Limited | Information & communication | 2013 |
| Telonic Instruments Limited | Wholesale & retail | 1982 |
| Temad Collections Ltd | Wholesale & retail | 2020 |
| Temperature Technology Limited | Wholesale & retail | 1998 |
| Templeton Fireplaces Ltd | Construction | 2024 |
| Templeton Time-Share Limited | Professional & scientific | 1982 |
| Tempus Accountants Ltd | Professional & scientific | 2026 |
| Tender Care (UK) Limited | Health & social care | 2014 |
| Tensorhawk Technologies Ltd | Manufacturing | 2025 |
| Tepeo Ltd | Manufacturing | 2018 |
| Terra Monile Ltd | Manufacturing | 2024 |
| Terra Nova Consulting Ltd | Information & communication | 2022 |
| Terra Vitum Ltd | Agriculture & fishing | 2023 |
| Terrafirma Driveways & Courtyards Ltd | Administrative & support | 2025 |
| Terrafirma Driveways Ltd | Administrative & support | 2025 |
| Terramed Limited | Manufacturing | 2024 |
| Terranauts Ltd | Real estate | 2025 |
| Terranova Roofing Contractors Ltd | Administrative & support | 2025 |
| Tettenhall (West Hill Road) Management Company Limited | Real estate | 2008 |
| Tevfik Property Ltd | Real estate | 2015 |
| Tevfik Property Management Ltd | Real estate | 2020 |
| Texperts Consulting Ltd | Information & communication | 2010 |
| TGG Water Services Ltd | Construction | 2021 |
| Thaaru Global Ltd | Wholesale & retail | 2025 |
| Thames Court Reading Freehold Company Limited | Real estate | 2010 |
| Thames Software Solutions Ltd | Information & communication | 2015 |
| Thames Valley Aesthetics Ltd | Other services | 2021 |
| Thames Valley Brickwork Ltd | Construction | 2021 |
| Thames Valley Leasing Limited | Financial services | 2009 |
| Thames Valley Roofing & Property Maintenance Ltd | Construction | 2015 |
| Thames Walk Management Company Limited | Real estate | 2007 |
| Thames Way Physio Ltd | Health & social care | 2011 |
| Thanet Real Estate Ltd | Real estate | 2025 |