| Theresian Global Education Limited | Information & communication | 2023 |
| Thereunionshowuk Ltd | Administrative & support | 2021 |
| Thesoftskillspartnership Ltd | Professional & scientific | 2021 |
| Thestorehub Ltd | Wholesale & retail | 2023 |
| Think Perception Ltd | Information & communication | 2014 |
| Thinkingbigger Ltd | Information & communication | 2023 |
| Thinkmatica Limited | Information & communication | 2023 |
| Third Edge Capital Ltd | Information & communication | 2017 |
| Thirteen Interior Design Ltd | Professional & scientific | 2016 |
| Thistle Aviation Holdings Ltd | Financial services | 2026 |
| Thistlebrook Farms Limited | Agriculture & fishing | 1963 |
| Thomas Bell-Wright International Limited | Professional & scientific | 2022 |
| Thomas Daniel Professional Decorators Limited | Construction | 2018 |
| Thomas Hughes Ltd | Professional & scientific | 2018 |
| Thomas Martha Evans Consulting Ltd | Professional & scientific | 2025 |
| Thomdell Developments (2) Limited | Construction | 2017 |
| Thomdell Developments Limited | Construction | 2011 |
| Thomdell Group Ltd | Real estate | 2022 |
| Thomley Wellness Limited | Arts & recreation | 2025 |
| Thompson Investment Management Ltd | Extraterritorial | 2017 |
| Thornbrook Close (Management Company) Limited | Real estate | 2025 |
| Thoth Consultancy Ltd | Professional & scientific | 2025 |
| Thread & Fibre Ltd | Manufacturing | 2024 |
| Three Chairs Limited | Other services | 2025 |
| Three Counties Plumbing Ltd | Construction | 2006 |
| Three Counties Scaffolding Limited | Construction | 2012 |
| Three Herons Limited | Hospitality | 2018 |
| Three Lines Consulting Limited | Professional & scientific | 2025 |
| Three Shires Stoves Limited | Construction | 2023 |
| Three Squared Live Limited | Information & communication | 2013 |
| Three Squared Production Limited | Information & communication | 2011 |
| Threeco Investments Limited | Real estate | 2023 |
| Thrims Properties Limited | Real estate | 1962 |
| Thrive Bucks Limited | Health & social care | 2023 |
| Throne Capital Consulting Limited | Professional & scientific | 2022 |
| Thrussell Scaffolding Ltd | Construction | 2021 |
| THS Handling Limited | Transport & logistics | 2018 |
| Thumbsie Ltd | Wholesale & retail | 2016 |
| Thurkettle Vehicle Engineers Ltd | Wholesale & retail | 2010 |
| Tickets for Troops | Other services | 2009 |
| TIE Prestige Cars Ltd | Transport & logistics | 2022 |
| Tiger Robot Ltd | Professional & scientific | 2017 |
| Tigerlily Jewellery Ltd | Wholesale & retail | 2007 |
| Tijo Professional Management Limited | Professional & scientific | 2009 |
| Tile Xpert Limited | Wholesale & retail | 2024 |
| Till Machine Ltd | Information & communication | 2019 |
| Tilley MR Solutions Limited | Professional & scientific | 2024 |
| TIM Invest Limited | Real estate | 2025 |
| TIM Sweetman Interiors Limited | Construction | 2007 |
| TIM Walker (Restorations) Ltd | Manufacturing | 2001 |
| Timba Systems Ltd | Wholesale & retail | 2025 |
| Timberlake Interiors Ltd | Manufacturing | 2019 |
| Timbrit Consulting Ltd | Information & communication | 2021 |
| Time and Tide Commercial Finance Ltd | Financial services | 2019 |
| Timely Financial Planning Limited | Professional & scientific | 2023 |
| Timi Decs Ltd | Construction | 2016 |
| Timist Ltd | Information & communication | 2021 |
| Timothy Foxx Limited | Extraterritorial | 2009 |
| Tina Health & Care Limited | Health & social care | 2022 |
| Tincupsocial Limited | Administrative & support | 2020 |
| Tiny Luxuries Co Ltd | Wholesale & retail | 2025 |
| Tiny Stitch Ltd | Wholesale & retail | 2024 |
| Tionic Limited | Health & social care | 2017 |
| TIP Top SP Ltd | Wholesale & retail | 2025 |
| Tishna Limited | Real estate | 2009 |
| Titan Engineering Limited | Wholesale & retail | 1980 |
| TJ Hamilton Consulting Ltd | Professional & scientific | 2012 |
| TJ Memorials Limited | Manufacturing | 2025 |
| TJK Driver Training Services Ltd | Education | 2021 |
| TK Stage Services Ltd | Arts & recreation | 2024 |
| TK Structures Ltd | Professional & scientific | 2026 |
| TKB Joinery Ltd | Manufacturing | 2021 |
| TKN (UK) Ltd | Wholesale & retail | 2014 |
| TKT SCM Consulting Limited | Information & communication | 2024 |
| TLC Drainage Solutions Ltd | Water & waste | 2016 |
| TLD Consulting Services Limited | Professional & scientific | 2009 |
| TLK Change Consulting Ltd | Information & communication | 2016 |
| Tlkt Ltd | Information & communication | 2021 |
| Tlsm Consulting Limited | Professional & scientific | 2024 |
| TM Risk Partners Holdings Ltd | Financial services | 2026 |
| TMC Business Solutions Limited | Professional & scientific | 2014 |
| Tmgs Construction Ltd | Construction | 2018 |
| Tmjs Associates Limited | Professional & scientific | 2021 |
| TNM DON Ltd | Professional & scientific | 2025 |
| Tnm/Mazs Limited | Health & social care | 2016 |
| TNO Construction Ltd | Construction | 2025 |
| TNS Fitness Ltd | Arts & recreation | 2024 |
| TO PM Ltd | Real estate | 2021 |
| Tobias James Installations Ltd | Construction | 2014 |
| Toby Alington Limited | Information & communication | 2013 |
| Toby Scott Photography Limited | Professional & scientific | 2013 |
| TOD Utilities Ltd | Construction | 2020 |
| Todbury Leisureproperty Ltd | Real estate | 2022 |
| Togather Limited | Administrative & support | 2020 |
| Tokhang Gang Ltd | Information & communication | 2023 |
| Tollejo Ventures Ltd | Professional & scientific | 2020 |
| TOM Driver Creative Ltd | Professional & scientific | 2012 |
| TOM Herlihy Ltd | Construction | 2025 |
| Tomas Chovan Ltd | Transport & logistics | 2025 |
| Tomes Builders Limited | Construction | 2004 |