| THE Portfolio Partnership Ltd | Real estate | 2022 |
| THE Priory Clay Target Centre Ltd | Arts & recreation | 2014 |
| THE Priory GUN Services Ltd | Other services | 2023 |
| THE Property Group (Essex) Limited | Real estate | 2023 |
| THE Quiet MAN (Hertford) Limited | Hospitality | 2023 |
| THE Quiet MAN (Holdings) Ltd | Financial services | 2026 |
| THE Residence 1955 Limited | Information & communication | 2017 |
| THE Restaurant Chain Limited | Hospitality | 2013 |
| THE Rosebery Partnership | | 1988 |
| THE Serene Clinic Ltd | Other services | 2025 |
| THE Sibley&Son's Company Limited | Extraterritorial | 2024 |
| THE Standard Steam Locomotive Company Limited | Manufacturing | 1996 |
| THE Sustainable Marketing Suite Company Limited | Extraterritorial | 2022 |
| THE Tool Sock Company Ltd | Wholesale & retail | 2021 |
| THE Trade Inn Witham Ltd | Wholesale & retail | 2011 |
| THE Two Percent Ltd | Information & communication | 2010 |
| THE Upholders Charity | Education | 2019 |
| THE Wylie Group (Construction) Ltd | Construction | 2015 |
| THE Wylie Group Holdings Limited | Health & social care | 2020 |
| The-Butterfly-Effect Limited | Information & communication | 2026 |
| Themis GC Consulting LLP | | 2025 |
| Thetecgroup Ltd | Construction | 2025 |
| Thetradecover Limited | Information & communication | 2026 |
| Third Empowerment Limited | Professional & scientific | 2022 |
| Thompson Electrical Ltd | Construction | 2019 |
| Thornlane Homes Limited | Construction | 2006 |
| Thought to Thesis Limited | Education | 2025 |
| Threezed Limited | Health & social care | 2014 |
| TI and TY Ltd | Wholesale & retail | 2024 |
| Tibbitts Trading Ltd. | Financial services | 2001 |
| TILE4U Ltd | Construction | 2011 |
| Tironia Ltd | Information & communication | 2019 |
| TKP Consulting Services Limited | Professional & scientific | 2006 |
| TL Paving Ltd | Construction | 2021 |
| TNV Care and Support Services Ltd | Public administration | 2025 |
| TOI Consulting Limited | Administrative & support | 2016 |
| Tomsy's Windows Limited | Administrative & support | 2023 |
| Top MAN and Van - London Removals Ltd | Transport & logistics | 2012 |
| Top to TOE Beauty Ltd | Other services | 2020 |
| Torrington Ltd | Real estate | 2020 |
| Torrington Remodelling Limited | Construction | 2022 |
| Totalrewards Limited | Administrative & support | 2026 |
| Tout & Brew Limited | Professional & scientific | 2013 |
| Tower Bridge Studios Limited | Information & communication | 2024 |
| Town & Country Property Lettings Ltd | Financial services | 2016 |
| Town and Country Lettings Ltd | Real estate | 2025 |
| TP CEM Services Ltd | Other services | 2025 |
| TPH Services Limited | Manufacturing | 2004 |
| Tpmg Limited | Information & communication | 2011 |
| Tracked Carriers Limited | Manufacturing | 2025 |
| Trade Boats Limited | Wholesale & retail | 2020 |
| Trade Four Trade Ltd | Professional & scientific | 2025 |
| Trade Inn Limited | Wholesale & retail | 2024 |
| Tradelink Trade & Tech Limited | Information & communication | 2023 |
| Tramco London Limited | Other services | 2020 |
| Travels Boutique Ltd | Administrative & support | 2011 |
| Trev Consultancy Limited | Other services | 2014 |
| Trio Surveys and Compliance Limited | Households | 2026 |
| Tristar Publications Limited | Professional & scientific | 1957 |
| Trivista Properties Ltd | Real estate | 2025 |
| Trivium FM Limited | Professional & scientific | 2017 |
| Trotters Cafe UK Ltd | Hospitality | 2023 |
| True Virtues Training Ltd | Education | 2019 |
| Trusted Equity Release Limited | Extraterritorial | 2022 |
| Trusted Financial Group Limited | Extraterritorial | 2022 |
| Trusted Home Finance Limited | Financial services | 2022 |
| Trusty Squirrel Ltd | Professional & scientific | 2025 |
| TTR Vehicle Solutions Ltd | Wholesale & retail | 2026 |
| Tunmarsh Consulting Ltd | Information & communication | 2018 |
| Turem Limited | Real estate | 2022 |
| Turk Visuals Limited | Professional & scientific | 2026 |
| Turrall Limited | Real estate | 2020 |
| TV Republic Limited | Information & communication | 2011 |
| Twenty Eight Design Limited | Professional & scientific | 2015 |
| Two Tails Crossfit Retail Ltd | Wholesale & retail | 2021 |
| Tyne & Wear Internet Services Limited | Professional & scientific | 1995 |
| Tyre-Smart (Essex) Ltd | Wholesale & retail | 2014 |
| UBF Sales & Marketing Ltd Limited | Hospitality | 2020 |
| Uden Services Ltd | Professional & scientific | 2019 |
| UDM Contracts Limited | Construction | 2026 |
| UK Fire and Security Doors Limited | Manufacturing | 2014 |
| UK Floors Ltd | Construction | 2014 |
| UK FSD Limited | Administrative & support | 2021 |
| UK Image Limited | Professional & scientific | 2006 |
| UK Link Ltd | Hospitality | 2012 |
| UK the Loft Ltd | Construction | 2025 |
| Ukald EDU Ltd | Administrative & support | 2015 |
| Ultra Nine Limited | Information & communication | 2024 |
| Unique Results Limited | Education | 2016 |
| Uniquefabs Limited | Health & social care | 2019 |
| United Malt (Canada) Holdings UK Limited | Manufacturing | 2009 |
| UNO Cleaning Services Ltd | Administrative & support | 2026 |
| Unodent Ltd | Extraterritorial | 2007 |
| Urban Book-Keeping Services Limited | Professional & scientific | 2025 |
| Urban Geology Limited | Professional & scientific | 2005 |
| Urban Regeneration Solutions Ltd | Construction | 2020 |
| Ushers Print & Design Limited | Administrative & support | 2006 |
| Usus Investment Limited | Professional & scientific | 2008 |
| Uthavi Ltd | Professional & scientific | 2021 |
| UX808 Consulting Ltd | Information & communication | 2025 |