| T Sparks Ltd | Construction | 2025 |
| T&B Corporate Accounting Ltd | Professional & scientific | 2015 |
| T&J London Ltd | Construction | 2015 |
| T&M Distribution and Warehousing Ltd | Transport & logistics | 2019 |
| T&S Consultancy Services Ltd | Professional & scientific | 2023 |
| T&T Hand Car Wash Limited | Wholesale & retail | 2015 |
| T. Mayne Ltd | Administrative & support | 2006 |
| T. Patton Limited | Construction | 1982 |
| T.H.F.C. Limited | Extraterritorial | 1998 |
| T.K Prime Estates Limited | Real estate | 2025 |
| T444Z Limited | Other services | 2009 |
| TA Goods Limited | Wholesale & retail | 2026 |
| TA55 Limited | Construction | 2025 |
| Tabidor Ltd | Information & communication | 2020 |
| Tactical JIU Jitsu Ltd | Arts & recreation | 2018 |
| Taenite Limited | Wholesale & retail | 2021 |
| TAG Security Systems Ltd | Administrative & support | 2010 |
| Tahtex Consulting Limited | Financial services | 2017 |
| Taidap Healthcare Ltd | Health & social care | 2023 |
| Talent Building for Education Limited | Education | 2023 |
| Talent LED Growth Ltd | Administrative & support | 2023 |
| Talscent Ltd | Wholesale & retail | 2020 |
| Tambax Limited | Health & social care | 2023 |
| Tame Alliance Ltd | Health & social care | 2022 |
| Tamika Ltd | Health & social care | 2021 |
| Tammi Investments Ltd | Real estate | 2025 |
| TAN Express Harlow Ltd | Other services | 2024 |
| TAN Group Essex Ltd | Other services | 2024 |
| Tanase & SON Limited | Construction | 2020 |
| Tanbay HR and Security Solutions Ltd | Administrative & support | 2021 |
| Tandrose Ltd | Professional & scientific | 2024 |
| Tanfox Limited | Financial services | 2025 |
| Tanra Limited | Hospitality | 2024 |
| Tanys Court Estate Management Company Limited | Households | 2008 |
| TAP & PAY Solutions Ltd | Information & communication | 2018 |
| Tapxpress Ltd | Wholesale & retail | 2025 |
| Targa Building Limited | Construction | 2025 |
| Target Point Advertising Limited | Professional & scientific | 2025 |
| Tarh Medicals Ltd | Health & social care | 2023 |
| Tarka Ridge (Yelland) Management Company Limited | Real estate | 2018 |
| Taroba Medical Limited | Health & social care | 2024 |
| Tarquin Medical Limited | Health & social care | 2022 |
| TAS Consultancy Services Ltd | Information & communication | 2024 |
| Task Plan Go Limited | Wholesale & retail | 2020 |
| TASK2CLEAN Ltd | Transport & logistics | 2022 |
| Tasker Technologies Limited | Information & communication | 1999 |
| Tax Calculations Limited | Professional & scientific | 2014 |
| Taxon Accountancy Ltd | Professional & scientific | 2019 |
| Taylor & Cook Limited | Manufacturing | 2019 |
| Taylor Gray Holdings Ltd | Real estate | 2021 |
| Taylor Made Entertainment Ltd | Arts & recreation | 2024 |
| Taylor Made Global Ltd | Administrative & support | 2024 |
| Tayo Adegun Limited | Health & social care | 2022 |
| TB Barbers Limited | Other services | 2024 |
| TBE Ltd | Information & communication | 2014 |
| TC Cleaning Solutions Ltd | Administrative & support | 2025 |
| TCC Communications Limited | Information & communication | 2015 |
| TCM Associates Limited | Manufacturing | 1998 |
| TCR (London) Limited | Hospitality | 2012 |
| TCS Cleaning Services Limited | Administrative & support | 2025 |
| TDC Car Sales Ltd | Wholesale & retail | 2024 |
| Teach Education First Limited | Administrative & support | 2024 |
| Team OMG Limited | Wholesale & retail | 2010 |
| Team Rhino Ltd | Information & communication | 2019 |
| Tech Titans Hub Ltd | Wholesale & retail | 2024 |
| Tech Twenty One Limited | Information & communication | 2019 |
| Tech-Graph Services Ltd | Professional & scientific | 2013 |
| TECH65 Ltd | Information & communication | 2021 |
| Techdrix Ltd | Information & communication | 2025 |
| Techeden UK Ltd | Wholesale & retail | 2026 |
| Technical Plus Ltd | Real estate | 2017 |
| Technics Risk Services & Global Enterprises Ltd | Transport & logistics | 2013 |
| Techniplas Limited | Manufacturing | 1999 |
| Technomadic Technical Services Ltd | Information & communication | 2023 |
| Techpoint Distribution Limited | Wholesale & retail | 2011 |
| Techpoint Investments Ltd | Real estate | 2021 |
| Techrec Solutions Ltd | Administrative & support | 2015 |
| Tecna Display Limited | Manufacturing | 1994 |
| Teddix Rail Solutions Limited | Construction | 2017 |
| Teddy Electrical Services Ltd | Construction | 2017 |
| Teddy Labs Ltd | Information & communication | 2026 |
| Teemade Consultancy Ltd | Information & communication | 2023 |
| Teen Tech Talent Limited | Health & social care | 2023 |
| Tees-Surgicare Limited | Health & social care | 2020 |
| Tejflot Homes Ltd | Real estate | 2025 |
| Tekon (UK) Limited | Professional & scientific | 2007 |
| Telam Limited | Health & social care | 2025 |
| Telecommunications Consultancy & Business Development Services Limited | Information & communication | 2013 |
| Telesys Group Limited | Information & communication | 2011 |
| Telesys Services Ltd | Administrative & support | 2025 |
| Telfosystems Limited | Information & communication | 2025 |
| Telro Limited | Wholesale & retail | 2022 |
| Temarin Limited | Health & social care | 2022 |
| Tembol Prestigious Inn Ltd | Real estate | 2024 |
| Temple Fields 514 Limited | Professional & scientific | 2002 |
| Temple Fields 515 Limited | Manufacturing | 1961 |
| Temple Fields 522 Limited | Professional & scientific | 2005 |
| Temple Fields 523 Limited | Professional & scientific | 2005 |
| Temple Fields 530 Limited | Professional & scientific | 1964 |
| Temple Gate (One) Dollis Hill Management Company Limited | Households | 1994 |