| Tillerant Limited | Professional & scientific | 2011 |
| TIM Mott Associates Limited | Professional & scientific | 1977 |
| Time OUT Activities Limited | Real estate | 1999 |
| TIME2FOCUS Ltd | Administrative & support | 2017 |
| Tine Limited | Other services | 2008 |
| TIP Top London Ltd | Other services | 2025 |
| Tip-Top Property Rentals Ltd | Real estate | 2019 |
| Titan Accounting Limited | Professional & scientific | 2005 |
| TJ Talent Solutions Ltd | Administrative & support | 2024 |
| TLC Portfolio Limited | Real estate | 2021 |
| TLP Digital Ltd | Information & communication | 2026 |
| TM London Limited | Professional & scientific | 2015 |
| TM Transport Ltd | Transport & logistics | 2011 |
| TML Investments 1 Limited | Real estate | 2022 |
| Tmrr Cafe Limited | Hospitality | 2023 |
| TNR Industries Ltd | Professional & scientific | 2018 |
| Tockenham Tyres & Auto Care Limited | Wholesale & retail | 2025 |
| Today Consulting Limited | Professional & scientific | 2004 |
| Today's Enterprise Limited | Wholesale & retail | 2014 |
| Toikido Ltd | Administrative & support | 2020 |
| Toikido Studios Limited | Arts & recreation | 2025 |
| Tokeneffect Ltd | Information & communication | 2022 |
| Tolbea Ltd | Real estate | 2020 |
| TOM Hetherington Services Limited | Professional & scientific | 2010 |
| TOM Makins Consultancy Services Ltd | Information & communication | 2024 |
| TOM Parker Films Limited | Information & communication | 2015 |
| Toni Engelhard Ltd. | Wholesale & retail | 2016 |
| Tooley Limited | Wholesale & retail | 2020 |
| Top 2 Bottom Gutter and Cleaning Services Ltd | Administrative & support | 2024 |
| Top Flight Executive Ltd | Administrative & support | 2023 |
| Top Fruits Europe Limited | Wholesale & retail | 2023 |
| Top Grade Build Ltd | Construction | 2022 |
| Top Home Depot Limited | Wholesale & retail | 2024 |
| TOP2TOW Ltd | Transport & logistics | 2017 |
| Topdown Limited | Information & communication | 2008 |
| Topspread Ltd | Extraterritorial | 2026 |
| Total Motion Osteopathy & Sports Massage Clinic Ltd | Health & social care | 2024 |
| Total Plumbing Ltd | Construction | 2026 |
| Tove Limited | Wholesale & retail | 2018 |
| Tovey Associates Ltd | Professional & scientific | 2013 |
| Tower Projects (Europe) Limited | Professional & scientific | 2001 |
| Towfigh DIN Properties Ltd | Real estate | 2020 |
| TR4 Group Limited | Construction | 2023 |
| Tracey Lennon Limited | Information & communication | 2009 |
| Track Films Ltd | Information & communication | 2020 |
| Tradecity Car Sales Limited | Wholesale & retail | 2008 |
| Trained by Tyler Ltd | Other services | 2024 |
| Tramboo Holdings Limited | Real estate | 2021 |
| Transient Data Solutions Ltd | Information & communication | 2014 |
| Transit Community Support CIC | Information & communication | 2022 |
| Transit Smart Skills & Consult Ltd | Information & communication | 2022 |
| Tranta Limited | Information & communication | 2018 |
| Traverten Ltd | Real estate | 2017 |
| Treasury Wine Estates Emea Limited | Wholesale & retail | 1986 |
| Treasury Wine Estates UK Brands Limited | Administrative & support | 2011 |
| Tredlan Partners Limited | Administrative & support | 2014 |
| Trendpie Fashion & Trend Solutions Limited | Other services | 2017 |
| Trendyist Ltd | Information & communication | 2014 |
| Tribes Furnishing Store Limited | Wholesale & retail | 2003 |
| Tricia King Consultancy & Coaching Ltd | Professional & scientific | 2019 |
| Trident Media Guard UK Ltd | Professional & scientific | 2009 |
| Trigeminal Nerve Limited | Health & social care | 2012 |
| Trinity Capital Partners Limited | Financial services | 2016 |
| Trinity Digital Technology Limited | Information & communication | 2016 |
| Trioedge Properties Ltd | Real estate | 2024 |
| Triplemm Ltd | Professional & scientific | 2025 |
| Triplur Limited | Transport & logistics | 2019 |
| Tritact Ltd | Information & communication | 2019 |
| Trivela Football Coaching Ltd | Education | 2024 |
| Trjp Ltd | Arts & recreation | 2025 |
| Tropical Britain Limited | Agriculture & fishing | 2011 |
| TRU Leaf Ltd | Wholesale & retail | 2025 |
| True Beauty Salon Limited | Other services | 2004 |
| True West Trading Ltd | Wholesale & retail | 2021 |
| Trusted Games Ltd | Professional & scientific | 2012 |
| Truvio Solutions UK Ltd | Wholesale & retail | 2022 |
| TRX Group Ltd | Other services | 2025 |
| Tsaiming Limited | Information & communication | 2009 |
| TSC Property Developments Limited | Construction | 2023 |
| TT Editorial Ltd | Professional & scientific | 2022 |
| Tubio Moritan Limited | Real estate | 2021 |
| Tuck Estates Limited | Real estate | 2016 |
| Tudor Court Freehold (NO 1) Limited | Households | 2007 |
| Tudor Court Freehold (NO 2) Limited | Households | 2007 |
| Tudor House Freehold Limited | Households | 2007 |
| Tumby Business Consulting Ltd | Administrative & support | 2019 |
| Tumby Enterprise Limited | Financial services | 2019 |
| Tunkara's Healthcare Limited | Health & social care | 2024 |
| Turbine Maintenance & Repairs Ltd | Manufacturing | 2018 |
| Turbo Developments Limited | Manufacturing | 2011 |
| Turbo Enterprises Limited | Real estate | 2018 |
| Turen Ltd | Professional & scientific | 2021 |
| Turkish Fade Twickenham Ltd | Other services | 2024 |
| Turner's House Trust | Arts & recreation | 2005 |
| Turtle Shells Limited | Real estate | 2013 |
| TW Airport Drive Ltd | Wholesale & retail | 2023 |
| TW Fitness for Women Ltd | Arts & recreation | 2022 |
| TW Group Build Ltd | Construction | 2024 |
| TW Property Management Ltd | Real estate | 2018 |
| TW1 Food and Wine Ltd | Wholesale & retail | 2022 |