| THE Small Herd Ltd | Wholesale & retail | 2021 |
| THE Smart Lighting People Ltd | Wholesale & retail | 2025 |
| THE Soames Consultancy Limited | Professional & scientific | 2023 |
| THE Social Elevator Marketing Group Ltd | Professional & scientific | 2024 |
| THE Space International Group Ltd | Professional & scientific | 2021 |
| THE Spirited London Ltd | Hospitality | 2026 |
| THE Stephens and Stephens Group Ltd | Financial services | 2019 |
| THE Storm Collaborative Ltd | Professional & scientific | 2022 |
| THE Studio MG Limited | Other services | 2019 |
| THE Study BED Company Limited | Manufacturing | 2006 |
| THE Sugar Shack London Limited | Wholesale & retail | 2025 |
| THE Surplus Studio Ltd | Wholesale & retail | 2026 |
| THE Sussex Knee and HIP Surgeon Limited | Health & social care | 2021 |
| THE Swallows (Blocks a, B, C, D, and P) Management Company Limited | Households | 1995 |
| THE Syndicate Group Ltd | Administrative & support | 2026 |
| THE Talley Club Ltd | Manufacturing | 2025 |
| THE Tea Room Bricket Wood Ltd | Hospitality | 2023 |
| THE Theatre Channel Ltd | Information & communication | 2021 |
| THE Third Company Limited | Arts & recreation | 2010 |
| THE Thomas More Residents Association Limited | Households | 2001 |
| THE TK Maxx and Homesense Foundation | Other services | 2014 |
| THE Todd Group Limited | Professional & scientific | 2004 |
| THE Toothplace Dental Surgery Limited | Health & social care | 2010 |
| THE Towers Engel Park Limited | Real estate | 1992 |
| THE Trade Marketing Group Ltd | Wholesale & retail | 2023 |
| THE Two Paths Design Ltd | Wholesale & retail | 2023 |
| THE Ultimate Jobs Board Ltd | Professional & scientific | 2024 |
| THE United Suburbs of Amerika Ltd | Professional & scientific | 2020 |
| THE Vibe Watford Limited | Information & communication | 2009 |
| THE Village Group Limited | Hospitality | 2026 |
| THE Wall Art Club Limited | Manufacturing | 2020 |
| THE Wandle Quarter Management Company Limited | Households | 2022 |
| THE Watford Locksmith Ltd | Wholesale & retail | 2025 |
| THE Welbeck Street Partnership | | 2001 |
| THE White House (Marlowes) Management Limited | Households | 2025 |
| THE Wifi Specialist Ltd | Information & communication | 2021 |
| THE Wild Heart Coaching Ltd | Professional & scientific | 2023 |
| THE Willchris Settlement Limited | Professional & scientific | 2010 |
| THE Working Partnership Company Ltd | Professional & scientific | 2007 |
| THE Workr Group Limited | Professional & scientific | 2014 |
| THE Wright Approach International Limited | Professional & scientific | 2005 |
| THE Xavi Lessi Summer Project Limited | Health & social care | 2025 |
| THE Yoga Attic Ltd | Arts & recreation | 2020 |
| THE4 Construction Ltd | Construction | 2025 |
| Thecoachcompany.Co.Uk Ltd | Transport & logistics | 2021 |
| Thedojo.Org.Uk Ltd | Education | 2014 |
| Thegreekpittahemelhempstead Limited | Hospitality | 2025 |
| Thekanady Limited | Real estate | 2013 |
| Thekbs IT Consultants Ltd | Information & communication | 2022 |
| Theme Park 101 Ltd | Information & communication | 2026 |
| Themisto Music Limited | Information & communication | 2008 |
| Theo Auto Ltd | Wholesale & retail | 2025 |
| Theoxfordcoachcompany.Co.Uk Ltd | Transport & logistics | 2025 |
| Therapy Ventures Ltd | Information & communication | 2018 |
| Thermo Heating & Cooling Ltd | Construction | 2025 |
| Thestudy Limited | Professional & scientific | 2009 |
| They and SHE Builds London / Beyond Limited | Education | 2020 |
| Think - O'Sullivan Ltd | Professional & scientific | 2005 |
| Think Wise Limited | Wholesale & retail | 2022 |
| Thinkle Limited | Information & communication | 2019 |
| Thinkwise Software Ltd | Information & communication | 2021 |
| Thiopath Ltd | Professional & scientific | 2026 |
| Third Circle Productions Limited | Administrative & support | 2026 |
| Third Collective Events Ltd | Professional & scientific | 2026 |
| Third EYE Group UK Limited | Administrative & support | 2006 |
| Thirsty Work Bars Education Academy Limited | Hospitality | 2026 |
| Thirsty Work Bars Ltd | Hospitality | 2018 |
| THIRTEEN22 Consulting Limited | Agriculture & fishing | 2011 |
| Thirty Eleven Consulting Limited | Professional & scientific | 2017 |
| Thirupathy Limited | Health & social care | 2023 |
| Thomas & Starr Limited | Construction | 2024 |
| Thomas Ellis Design Limited | Professional & scientific | 2004 |
| Thompson Global Ltd | Wholesale & retail | 2024 |
| Thompson Instruments Limited | Professional & scientific | 2007 |
| Thor Enterprise Limited | Wholesale & retail | 2010 |
| Thor Systems Limited | Information & communication | 1996 |
| Thorium Security Payroll Limited | Administrative & support | 2019 |
| Thorne Barton Estates Limited | Construction | 1984 |
| Thornli Stores Limited | Wholesale & retail | 2018 |
| Thorpe & Brown Properties Ltd | Real estate | 2024 |
| Thorpe Residential Limited | Real estate | 2019 |
| Thraive Ltd | Administrative & support | 2022 |
| Three a Lane Limited | Wholesale & retail | 2011 |
| Three Flame Kebab Limited | Hospitality | 2025 |
| Three Lions Real Estates Ltd | Real estate | 2017 |
| Three Monkeys Properties Ltd | Real estate | 2021 |
| Three Rivers Homes Limited | Real estate | 2017 |
| Three Rivers Housing Developments LLP | | 2017 |
| Three Years From NOW Ltd | Professional & scientific | 2026 |
| Threecrowns Bold Ventures Ltd | Financial services | 2025 |
| Threesixty Events Ltd | Administrative & support | 2001 |
| Thrillhouse Publishing Ltd | Information & communication | 2018 |
| Thrive Youth CIC | Education | 2022 |
| Thueman Coke Limited | Information & communication | 2023 |
| Thulasi & Easan London Enterprises Ltd | Hospitality | 2022 |
| Thunder Electrical Services Ltd | Construction | 2016 |
| Thunderbird International Ltd | Information & communication | 2022 |
| Thygametisrigged Limited | Professional & scientific | 2025 |
| Thythrone Services Ltd | Professional & scientific | 2022 |
| TI Land Partners Ltd | Construction | 2026 |