| Scoop News Limited | Information & communication | 2006 |
| SCR Trading Limited | Wholesale & retail | 2010 |
| Securlab Ltd | Information & communication | 2025 |
| Setminds 1 Limited | Professional & scientific | 2003 |
| Setminds 2 Limited | Professional & scientific | 2003 |
| Setminds Limited | Real estate | 2003 |
| Shelton Dogs Limited | Other services | 2020 |
| Shepherd Retail Consultants Ltd | Professional & scientific | 2019 |
| SID London Limited | Professional & scientific | 2024 |
| Simian Mischief Limited | Information & communication | 2006 |
| Simmons Limited | Construction | 2019 |
| Sixty Developments Limited | Real estate | 2023 |
| Sophells Developments Limited | Construction | 2021 |
| St&N Holdings Limited | Financial services | 2025 |
| Stanger Materials Testing & Consultancy Limited | Professional & scientific | 2020 |
| Stillmen Limited | Real estate | 2003 |
| Strand International Assetmanagement Ltd | Real estate | 2024 |
| STRIVE2LEARN Ltd | Extraterritorial | 2015 |
| Sunday Social Ltd | Real estate | 2018 |
| Sureflow (2023) Ltd | Water & waste | 2023 |
| Tanqueray Investments Limited | Construction | 2016 |
| Tanqueray-Hewitt Limited | Real estate | 2011 |
| Tanqueray-Hewitt Properties Limited | Real estate | 2023 |
| Taylor Watchman Limited | Professional & scientific | 2025 |
| Team Temple Towers Limited | Real estate | 2016 |
| Techright Limited | Information & communication | 2015 |
| Teledesign Services Limited | Information & communication | 2024 |
| Temple Violet Ltd | Administrative & support | 2003 |
| TEN TEN Property Holdings Limited | Real estate | 2021 |
| TEN TEN Resources Limited | Education | 2015 |
| Teng FEI Ltd | Hospitality | 2024 |
| Tewin Hill Farm Limited | Real estate | 2000 |
| That's the Badger Lighting Design Ltd | Arts & recreation | 2022 |
| THE Book Monitor Ltd | Professional & scientific | 2013 |
| THE Dorothea Lakes Ltd | Mining & quarrying | 1991 |
| THE Green Container Co Limited | Transport & logistics | 2012 |
| THE Letchworth Garden City Educational Trust | Education | 1983 |
| THE Limited | Other services | 2006 |
| THE Lotus Connection Limited | Financial services | 2025 |
| THE Lounge VET Ltd | Professional & scientific | 2023 |
| THE Peter Dodge Partnership Limited | Other services | 2017 |
| THE Racquet Barn Limited | Arts & recreation | 2025 |
| THE Ruth Campbell Partnership Limited | Real estate | 2002 |
| Thinkmoda Limited | Professional & scientific | 2019 |
| TLC Group (Developments) Limited | Construction | 2017 |
| TOM Burton Design Limited | Information & communication | 2004 |
| Tongs Enterprise Ltd | Health & social care | 2024 |
| Tortmay Properties Limited | Households | 1978 |
| Tourism Society(The) | Other services | 1978 |
| Trident Energy International Ltd | Administrative & support | 2009 |
| Trooper Limited | Financial services | 2013 |
| Underwood Furniture Limited | Wholesale & retail | 2020 |
| Upperglass Property Service Limited | Real estate | 2026 |
| VEM Properties Limited | Professional & scientific | 2006 |
| Verde Investments Limited | Professional & scientific | 1983 |
| Versais Fashion Limited | Wholesale & retail | 2023 |
| Vexler Global Consulting Limited | Professional & scientific | 2024 |
| Vivador & Sons Limited | Real estate | 2017 |
| Warrenwood Mews Management Company Limited | Real estate | 1997 |
| Weld of Metal Limited | Construction | 2025 |
| Wheeler Watts Holdings Limited | Financial services | 2022 |
| Wheldon Court Management Company Limited | Households | 2019 |
| Wilfrid Limited | Professional & scientific | 2010 |
| Wilfrid Smith Limited | Wholesale & retail | 1974 |
| Wiltek Developments Limited | Real estate | 2021 |
| Wright Start Day Nurseries Limited | Health & social care | 2010 |
| Wrights Housing Management Limited | Administrative & support | 2012 |
| Wrights of Welwyn Garden City Limited | Administrative & support | 2004 |
| Wrights Property Agents Limited | Real estate | 2022 |
| Your Estate Services Limited | Professional & scientific | 2019 |
| Yugen Blake Limited | Information & communication | 2013 |
| Zelig Associates Europe LLP | | 2012 |
| Zelig Brokerage LLP | | 2020 |
| Zelig Capital Partners Limited | Financial services | 2013 |