| Takoz Catering Ltd | Hospitality | 2023 |
| Tallentire Energy Limited | Energy | 2012 |
| Tamogna Technologies Ltd | Information & communication | 2014 |
| Tariffair Limited | | 1985 |
| Tax Shop (1997) Limited | Professional & scientific | 1996 |
| Taxcroft Limited | Real estate | 1995 |
| Taxease Services Limited | Professional & scientific | 2002 |
| Taylor Consulting Limited | Professional & scientific | 2005 |
| Taylor Small Direct Limited | Wholesale & retail | 2004 |
| Taylored Winning Solutions Limited | Professional & scientific | 2007 |
| Taylors Tools (Kings Langley) Limited | Wholesale & retail | 1977 |
| TCO Communications Limited | Administrative & support | 1995 |
| TD4 Group Ltd | Administrative & support | 2022 |
| Teach Together Ltd | Education | 2006 |
| Team Improvement Limited | Information & communication | 2006 |
| Teami Limited | Professional & scientific | 2005 |
| Tebo Fashion Limited | Wholesale & retail | 2022 |
| Technimatch Limited | Information & communication | 1999 |
| Techspark Limited | Professional & scientific | 2002 |
| Teddy Bear's Picnic Limited | Professional & scientific | 1997 |
| TEE KAY Enterprises Limited | Professional & scientific | 2002 |
| Teeco's Limited | Real estate | 2017 |
| Teknocom International Limited | Professional & scientific | 1992 |
| Telli Mini Market Ltd | Wholesale & retail | 2016 |
| Temptings Limited | Manufacturing | 2000 |
| Tempzone Ltd | Administrative & support | 2025 |
| Tenrec Limited | Information & communication | 2004 |
| Terence Edward Steel Limited | Manufacturing | 2003 |
| Ternex Limited | Manufacturing | 1951 |
| Terrazzolite Limited | Extraterritorial | 1992 |
| Terzia R Construction Ltd | Construction | 2025 |
| Thabo Tech Limited | Information & communication | 2019 |
| Tharun & Sano Ltd | Real estate | 2023 |
| That Feeling Ltd | Other services | 2019 |
| THE 147 Club Ltd | Hospitality | 2025 |
| THE 948 Sports Foundation | Professional & scientific | 2001 |
| THE African Collection Limited | Administrative & support | 2004 |
| THE Altro Group Trustees Limited | Professional & scientific | 1990 |
| THE Associated Business Partnership Limited | Professional & scientific | 2002 |
| THE Association of Event Organisers Limited | Other services | 1982 |
| THE Big Pitch Ltd | Arts & recreation | 2018 |
| THE Birches (Farnworth) Management Company Limited | Households | 2007 |
| THE Blue Marble Limited | Financial services | 2006 |
| THE Bright Yellow CAB Company Ltd | Transport & logistics | 2006 |
| THE British Horseball Association Limited | Arts & recreation | 1992 |
| THE Bull PEN Tea Rooms Limited | Hospitality | 2006 |
| THE Bull Theatre Ltd | Education | 2006 |
| THE Business Services Consortium Limited | Construction | 2001 |
| THE Cannabus Limited | Manufacturing | 2023 |
| THE Chocolate Tasting Club Limited | Wholesale & retail | 2003 |
| THE Commercial Property Investment Trust Fund LP | | 2002 |
| THE Complete Garage Door Company Ltd | Wholesale & retail | 2000 |
| THE Computing Workshop Limited | Information & communication | 1998 |
| THE Confidence Clinic Training Academy Limited | Education | 2019 |
| THE Craft ARK Limited | Arts & recreation | 2005 |
| THE Cunningham Consultancy Limited | Professional & scientific | 2002 |
| THE Dental Law Company Limited | Health & social care | 2000 |
| THE Eden Approach Limited | Other services | 2007 |
| THE Electronic Guide Limited | Information & communication | 1988 |
| THE Firethorn Trust | Education | 2003 |
| THE Food Therapy Clinic Limited | Health & social care | 2019 |
| THE GAS Shop Limited | Administrative & support | 1997 |
| THE GEE Corporation Limited | Information & communication | 1999 |
| THE Goat Inn Limited | Wholesale & retail | 2007 |
| THE Green Dragon VK Limited | Hospitality | 2022 |
| THE Harpenden Trust | Professional & scientific | 2006 |
| THE Health Barn Clinic Limited | Health & social care | 2005 |
| THE Holt Partnership Limited | Information & communication | 2003 |
| THE J. Shirvell Partnership | | 1994 |
| THE Keeley Carlisle Partnership Limited | Professional & scientific | 1998 |
| THE Kidlington Limited Partnership | | 1999 |
| THE Longmore Practice Limited | Administrative & support | 2006 |
| THE Meadows (Blocks Abce) Management Company Limited | Households | 1995 |
| THE Missing Element Ltd | Wholesale & retail | 2019 |
| THE Mixed Division | Professional & scientific | 2005 |
| THE Monarchist Movement Trust Limited | Other services | 2000 |
| THE National Association of Master Bakers Limited | Other services | 2001 |
| THE Natural Nail Company Limited | Administrative & support | 2004 |
| THE NEJ Ltd | Real estate | 2026 |
| THE Occupational Psychology Centre Limited | Professional & scientific | 1995 |
| THE Old Berkhamstedians Trust Company Limited | Other services | 2002 |
| THE Oneholer Limited | Wholesale & retail | 2001 |
| THE OPS Partnership Limited | Wholesale & retail | 2003 |
| THE Oriental Noodle Company Limited | Manufacturing | 1997 |
| THE Overtures Limited | Arts & recreation | 2002 |
| THE Practical Parenting Programme Limited | Professional & scientific | 2005 |
| THE Pronto BED Company Limited | Wholesale & retail | 2005 |
| THE Radlett Centre Trust | Arts & recreation | 1994 |
| THE Red House Broxbourne Management Company Limited | Households | 1991 |
| THE Rewind Project Limited | Information & communication | 2002 |
| THE Royston Golf Club Limited | Arts & recreation | 1998 |
| THE School of Kabbalah Limited | Education | 2002 |
| THE Tabor Group Ltd | Administrative & support | 2000 |
| THE Tasty Turk Ltd | Hospitality | 2020 |
| THE Thriving Company Limited | Professional & scientific | 2006 |
| THE Two Wheel Centre Limited | Wholesale & retail | 1991 |
| THE Valuation Partnership Limited | Professional & scientific | 2002 |
| THE Waterside Centre, Kings Langley | Health & social care | 1990 |
| THE Willows Whinney Lane Management Company Limited | Households | 2020 |
| THERAPY4ALL LLP | | 2006 |