| Taste of Pizza Ltd | Hospitality | 2017 |
| Taste Spice Fusion Ltd | Hospitality | 2025 |
| Tastes of Persia Limited | Administrative & support | 2018 |
| Tatla Holdings Limited | Real estate | 2025 |
| Tawanisi Limited | Professional & scientific | 2024 |
| Tax Compliance Ltd | Professional & scientific | 2021 |
| Taylor Alden Limited | Professional & scientific | 1977 |
| Taylor Hawkes (USA) Ltd | Administrative & support | 2022 |
| Taylor Hawkes Consulting Ltd | Administrative & support | 2021 |
| Taylor Hawkes Ltd | Administrative & support | 2014 |
| Taylor Hawkes Media & Creative Ltd | Administrative & support | 2022 |
| Taylor Jane Ltd | Real estate | 2020 |
| Taymaz Legal Consultancy Limited | Professional & scientific | 2021 |
| TBF Ventures Ltd | Real estate | 2022 |
| Tbrands Distributor Ltd | Hospitality | 2019 |
| TC Stiles Accountants Limited | Professional & scientific | 2025 |
| TCG Kids Limited | Wholesale & retail | 2003 |
| TCH Investments Limited | Administrative & support | 2017 |
| TCH Landscapes Ltd | Administrative & support | 2007 |
| Teachers 4 Limited | Education | 2014 |
| Teaghais Ltd | Real estate | 2019 |
| Team Focus Ltd | Administrative & support | 1989 |
| Teambuilder Recruitment Limited | Administrative & support | 1992 |
| Teapot Tea Shop Limited | Hospitality | 2013 |
| Tecdim Ltd. | Professional & scientific | 2017 |
| Tech Analyst Ltd | Financial services | 2020 |
| Tech Brand Limited | Professional & scientific | 2021 |
| Tech City Labs (Holdings) Limited | Financial services | 2023 |
| Tech City Labs Ltd | Information & communication | 2007 |
| Tech City Teams Ltd | Administrative & support | 2007 |
| Tech Connections Worldwide Limited | Professional & scientific | 2014 |
| Tech Ecosystem Limited | Professional & scientific | 2022 |
| Technofast Consulting Limited | Information & communication | 2000 |
| Technotrans UK Limited | Wholesale & retail | 2023 |
| Techotron Ltd | Wholesale & retail | 2022 |
| Techtronic Industries Emea Limited | Professional & scientific | 2011 |
| TECNOV8 Ltd | Information & communication | 2019 |
| Teddy Bell Investments Limited | Professional & scientific | 2024 |
| TEE BAG Creative Limited | Professional & scientific | 2017 |
| Tega & Sons Ltd | Professional & scientific | 2017 |
| TEK Tattoo Limited | Other services | 2026 |
| Telana Limited | Information & communication | 2003 |
| Telconet Limited | Information & communication | 2019 |
| Telstar Consulting Limited | Information & communication | 2018 |
| Temperament Dogs Ltd | Other services | 2016 |
| Temple Holdings Limited | Arts & recreation | 1959 |
| Templine Electrical Services Ltd | Energy | 2022 |
| TEN Four Drinks Limited | Professional & scientific | 2024 |
| TEN Four JB Limited | Wholesale & retail | 2025 |
| TEN Star Ltd | Wholesale & retail | 2026 |
| Tenant-Connect Ltd | Hospitality | 2012 |
| Tenngaling Ltd | Real estate | 2024 |
| Tensile Limited | Wholesale & retail | 2025 |
| TEO Rendering & Insulation Limited | Construction | 2021 |
| Teqnick Limited | Information & communication | 2009 |
| Termlex Inc. Limited | Information & communication | 2015 |
| Termon Consulting Ltd | Professional & scientific | 2023 |
| Terrafend Ltd | Manufacturing | 2012 |
| Terrafirma Ceramica Tiles Ltd | Wholesale & retail | 2018 |
| Terrain Plant (Holdings) Limited | Administrative & support | 1992 |
| Terry Eames Fire & Security Limited | Construction | 2000 |
| Tese Limited | Real estate | 2023 |
| Testavec Limited | Professional & scientific | 2017 |
| Tfdg Limited | Professional & scientific | 1998 |
| TFF Consultancy Ltd | Professional & scientific | 2022 |
| TGM Contractors Limited | Construction | 2011 |
| TGM Group Holdings Limited | Financial services | 2020 |
| Tgmas Property Solutions Limited | Real estate | 2020 |
| Tgsetdesign Ltd | Information & communication | 2024 |
| TH Paints and Wallpapers Ltd | Construction | 2024 |
| TH14 Ltd | Arts & recreation | 2024 |
| Thacmedical Ltd | Health & social care | 2022 |
| Thaldare Limited | Professional & scientific | 2025 |
| Thamco Ltd | Information & communication | 2025 |
| Thames Brewing Company Limited | Manufacturing | 2025 |
| Thames Castle Assets Limited | Real estate | 2020 |
| Thames Clearance Ltd | Water & waste | 2024 |
| Thames Court (Maidenhead) Residents Company Limited | Households | 1990 |
| Thames Forge Limited | Manufacturing | 1963 |
| Thames Hospice | Health & social care | 2004 |
| Thames Hospice Retail Ltd | Wholesale & retail | 1987 |
| Thames Medical Services Ltd | Health & social care | 2019 |
| Thames RUG Ltd | Wholesale & retail | 2014 |
| Thames Valley Capital Limited | Professional & scientific | 2008 |
| Thames Valley Construction Management Ltd | Construction | 2022 |
| Thames Valley Cricket Limited | Arts & recreation | 2014 |
| Thames Valley Design Consultants Limited | Professional & scientific | 2021 |
| Thames Valley Electricians Limited | Construction | 2013 |
| Thames Valley Landscapes Limited | Administrative & support | 2010 |
| Thames Valley Locks Limited | Construction | 2007 |
| Thames Valley Planners Ltd | Professional & scientific | 2012 |
| Thames Valley Primary Care Ltd | Health & social care | 2025 |
| Thames Valley Printers Limited | Manufacturing | 2011 |
| Thamesbridge Construction Limited | Construction | 2005 |
| Thamesbridge Holdings Ltd | Financial services | 2019 |
| Thamesbridge Plant Hire Limited | Administrative & support | 2017 |
| Thamesbridge Projects Ltd | Real estate | 2003 |
| Thameside Build Limited | Construction | 2005 |
| Thameside Events Limited | Extraterritorial | 2003 |
| Thameside Hospitality & Events Limited | Administrative & support | 2007 |