| Thorncroft Estates Limited | Extraterritorial | 2022 |
| Thph Investments Ltd | Wholesale & retail | 2016 |
| Thread Type Ltd | Wholesale & retail | 2021 |
| Threaded LDN Ltd | Wholesale & retail | 2025 |
| Three Brothers Private Limited | Wholesale & retail | 2023 |
| Three Button Mouse Limited | Administrative & support | 2009 |
| Three Percent Limited | Professional & scientific | 2013 |
| Three Sails Studios Limited | Information & communication | 2023 |
| Thurlow Wealth Ltd | Financial services | 2017 |
| THY Will BE Done (Spain) Ltd | Professional & scientific | 2017 |
| Tibi Cleaning Limited | Administrative & support | 2025 |
| Tidal Accounts Ltd | Extraterritorial | 2025 |
| Tidal Drift Consultants Limited | Construction | 2024 |
| Tidal Solutions Ltd | Manufacturing | 2025 |
| Tiddlypoo Limited | Information & communication | 2026 |
| Tide Solutions Ltd | Construction | 2010 |
| Tidebreaker Films Ltd | Information & communication | 2025 |
| TIG Therapies Limited | Health & social care | 2020 |
| Tiger Marketing Agency Limited | Professional & scientific | 2016 |
| Tight Five Ltd | Wholesale & retail | 2025 |
| Tighthead Investments | Financial services | 2025 |
| Tilbury Solutions Ltd | Professional & scientific | 2020 |
| Tilehurst Limited | Professional & scientific | 2015 |
| Tilious Ltd | Information & communication | 2016 |
| Tillian Consultancy Ltd | Education | 2012 |
| Tillmania Limited | Other services | 2010 |
| TIM Courier Services Ltd | Transport & logistics | 2022 |
| TIM Dessaint Ltd | Professional & scientific | 2019 |
| TIM Eldridge Limited | Information & communication | 2024 |
| Timand Consultants Limited | Professional & scientific | 2012 |
| Timand Property Holdings Ltd | Real estate | 2023 |
| Timber Displays Ltd | Manufacturing | 2003 |
| Timber DOT Ltd | Real estate | 2022 |
| Time (Sussex) Ltd | Other services | 2013 |
| Time Associates Ltd | Professional & scientific | 2021 |
| Time OUT Fostering Limited | Health & social care | 2004 |
| Time Tomorrow Limited | Professional & scientific | 2022 |
| Timecare 24 Ltd | Public administration | 2026 |
| Timesquare 2 Limited | Administrative & support | 2026 |
| Timewise Investments LLP | | 2025 |
| Timothy Millington Properties Ltd | Real estate | 2022 |
| Tina Crowley Ltd | Other services | 2026 |
| Tinashe Environmental Services Ltd | Professional & scientific | 2022 |
| Tineke Tammes Ltd | Other services | 2018 |
| Tingley Consulting Limited | Professional & scientific | 2022 |
| Tinkle Tock Productions Limited | Information & communication | 2020 |
| Tiny Squid Ltd | Information & communication | 2019 |
| Tipc Ltd | Other services | 2024 |
| Titan Construction SB Ltd | Construction | 2026 |
| Titan Dreams Limited | Real estate | 2018 |
| Titan Roof Masters Limited | Construction | 2025 |
| Titos Tapas Group Ltd | Hospitality | 2018 |
| Tixbeast Limited | Arts & recreation | 2025 |
| TJ 11 Developments Limited | Financial services | 2024 |
| TJ Invest Ltd | Real estate | 2020 |
| TJC Contract Services Ltd | Construction | 2018 |
| TJR Electrical Limited | Construction | 2007 |
| TJS Distribution Limited | Wholesale & retail | 2022 |
| TL & Co Developments Limited | Construction | 2024 |
| TL Homes Limited | Real estate | 2016 |
| TLC Carriage Masters Ltd | Administrative & support | 2024 |
| TLC Counselling Limited | Health & social care | 2013 |
| TLC Courts Ltd | Construction | 2020 |
| TLC Funeral Services Limited | Other services | 2019 |
| TLC Proclean Limited | Administrative & support | 2025 |
| TLG Productions Limited | Information & communication | 2021 |
| TLY Racing Ltd | Manufacturing | 2024 |
| TM Cabling Ltd | Information & communication | 2025 |
| TM Mowers Ltd | Manufacturing | 2021 |
| TMB Marketing & Communications Limited | Administrative & support | 1997 |
| TMC JJ Ltd | Professional & scientific | 2019 |
| Tmkf Group Ltd | Education | 2022 |
| Tmkf LLP | | 2017 |
| TMR Business Limited | Professional & scientific | 2020 |
| TMS Copy & Design Limited | Professional & scientific | 2013 |
| Tmtg Payments Limited | Administrative & support | 2004 |
| TN United Kingdom, Ltd. | Manufacturing | 1973 |
| TN1 Ltd | Information & communication | 2021 |
| TN1 Project Management Ltd | Professional & scientific | 2020 |
| TN1 Property Search Ltd | Real estate | 2020 |
| TNR Electrical Limited | Manufacturing | 2021 |
| TO Known Ltd | Wholesale & retail | 2025 |
| Toathill Investments Limited | Administrative & support | 1961 |
| Tobaccoathletic Limited | Administrative & support | 2003 |
| Tobias Construct Ltd | Construction | 2019 |
| Toby Tiger Limited | Manufacturing | 2001 |
| Toby Tiger Wholesale Limited | Wholesale & retail | 2007 |
| TOM Bellingham Media Limited | Financial services | 2023 |
| TOM Brock Electrical Limited | Construction | 2016 |
| TOM Craig Limited | Professional & scientific | 2003 |
| TOM Mccluskey Ltd | Information & communication | 2021 |
| Tommy Jones Developments Ltd | Construction | 2022 |
| Tommys Community Kitchen and Bakery CIC | Hospitality | 2025 |
| Tomsett Electrical Ltd | Construction | 2026 |
| Tonezone Consumables UK Ltd | Wholesale & retail | 2009 |
| Tony Maio Cars Limited | Wholesale & retail | 2020 |
| Tonz Construction Management Ltd | Construction | 2025 |
| Tool Revive Ltd | Manufacturing | 2025 |
| Top Glass Double Glazing Ltd | Construction | 2014 |
| Top Source Consulting Limited | Professional & scientific | 2019 |