| TCH Prop Ltd | Real estate | 2016 |
| TCL Services Ltd | Construction | 2018 |
| TDA Interiors Central Limited | Construction | 2010 |
| TDA Interiors South Limited | Construction | 2003 |
| Tdgp Ltd | Wholesale & retail | 2017 |
| TDV Consulting and Trading Limited | Wholesale & retail | 2010 |
| Teachappy Ltd | Education | 2020 |
| Team Dogz International Limited | Administrative & support | 2011 |
| Team Fred Properties Limited | Real estate | 2002 |
| Team V Property Ltd | Real estate | 2024 |
| Team V Sport Ltd | Education | 2016 |
| Teamforce Labour Limited | Construction | 2010 |
| Teatime Tutors Ltd | Education | 2014 |
| Tech Anvil Limited | Information & communication | 2012 |
| Tech-E Limited | Information & communication | 2010 |
| Techcastle Limited | Professional & scientific | 1993 |
| Techmap Ltd | Transport & logistics | 2020 |
| Techmettle Ltd | Information & communication | 2022 |
| Technica Efficacium Limited | Extraterritorial | 2024 |
| Techno Clean Ltd | Administrative & support | 2023 |
| Technocat Research and Technologies Ltd | Information & communication | 2025 |
| Technological Luxury Limited | Administrative & support | 2015 |
| Technology Junction Ltd | Information & communication | 2022 |
| Technology Traders Limited | Manufacturing | 2007 |
| Techycoders Ltd | Education | 2025 |
| Teddington ALE House Limited | Hospitality | 2025 |
| Teddington Property Group LLP | | 2023 |
| Teem Trade Ltd | Wholesale & retail | 2012 |
| Teeni & SON Ltd | Wholesale & retail | 2025 |
| Teenpra Ltd | Health & social care | 2023 |
| Teeny Tiney Nursery Ltd | Health & social care | 2026 |
| Teepee Estate Agents Limited | Real estate | 2024 |
| Teepee Properties Limited | Real estate | 2021 |
| Teepee Property Management Limited | Real estate | 2006 |
| Tekky Sturvs Ltd | Wholesale & retail | 2019 |
| Tekton Joinery Ltd | Construction | 2019 |
| Tele-Circuit Limited | Information & communication | 1959 |
| Telecom Investments Limited | Real estate | 1997 |
| Tell ME Everything Limited | Information & communication | 2018 |
| Telm Limited | Wholesale & retail | 2021 |
| Temoore Freight UK Ltd | Transport & logistics | 2020 |
| Template Estates Ltd | Real estate | 2018 |
| Temple Fortune Holdings Limited | Real estate | 2017 |
| Temptation Gifts (UK) Ltd | Wholesale & retail | 2012 |
| TEN 22 Group Ltd | Construction | 2023 |
| Terrace Apartments RTM Company Limited | Households | 2012 |
| Terrapolis Midlands Limited | Real estate | 2025 |
| Terry Richards Rigging Ltd | Construction | 2016 |
| Tersy Group Limited | Wholesale & retail | 2019 |
| Tersy Hold Co Limited | Financial services | 2023 |
| Tesla's Dream Electricals Ltd | Construction | 2015 |
| Testament Distribution Limited | Administrative & support | 2014 |
| Tetnight Education and Wellbeing International CIC | Education | 2011 |
| TF (Norfolk) Limited | Financial services | 2021 |
| TFF Properties Limited | Real estate | 2021 |
| TH Plumbing & Heating Limited | Construction | 2023 |
| Thai Jasmine Massage and Beauty Limited | Health & social care | 2024 |
| Thaifriends Massage & Training Ltd | Other services | 2024 |
| Thales Analytics Ltd. | Professional & scientific | 2013 |
| Thames Law Limited | Professional & scientific | 2019 |
| Thames Reinforcements Limited | Construction | 2006 |
| Thamesfield Property Group Limited | Real estate | 2024 |
| THE 1885 Lady Ltd | Information & communication | 2024 |
| THE 1922 Clothing Company Limited | Wholesale & retail | 2008 |
| THE Abbey Bar Leicester Ltd | Hospitality | 2026 |
| THE Ability Group Holdings Limited | Financial services | 2024 |
| THE Academy of Jewellery Holdings Ltd | Administrative & support | 2025 |
| THE Aldenham Foundation | Education | 1984 |
| THE Alpha Group 7C Limited | Other services | 2024 |
| THE Armada Group (Hospitality) Limited | Hospitality | 2023 |
| THE Art Building and Decorating Limited | Construction | 2013 |
| THE Art Imaginarium Ltd | Education | 2022 |
| THE Atlantic Inn Limited | Hospitality | 2015 |
| THE Automotive Inspector Limited | Wholesale & retail | 2014 |
| THE Avenue Company Limited | Professional & scientific | 1993 |
| THE Aviary (Management) Limited | Real estate | 2014 |
| THE Baby Nursery Limited | Wholesale & retail | 2020 |
| THE Beaufort Grange Management Company Limited | Households | 1997 |
| THE Beauty Room (Herts) Ltd | Other services | 2013 |
| THE BHE Hub Limited | Real estate | 2015 |
| THE Big Cart Private Ltd | Wholesale & retail | 2026 |
| THE Birthday Dreams Foundation | Administrative & support | 2023 |
| THE Boreham Wood Community Trust | Arts & recreation | 2018 |
| THE Borehamwood BMX Club CIC | Arts & recreation | 2025 |
| THE Bounces Road Surgery Ltd | Health & social care | 2023 |
| THE Brambles (Watford) Management Limited | Households | 1989 |
| THE Brand Conspiracy & Associates Limited | Professional & scientific | 2012 |
| THE Brickwork Group Limited | Financial services | 2016 |
| THE Bridge Care Centre Limited | Administrative & support | 2016 |
| THE Broadley Entertainment Group Limited | Professional & scientific | 1992 |
| THE Building Point Ltd | Construction | 2023 |
| THE Bulu Investment Company Limited | Real estate | 2021 |
| THE Caring Casa Limited | Real estate | 2021 |
| THE Carpentry COW Ltd | Arts & recreation | 2022 |
| THE Cat's Back Limited | Hospitality | 2015 |
| THE Cat's Whiskers Vintage Limited | Administrative & support | 2001 |
| THE Caves Bar and Grill Limited | Real estate | 2014 |
| THE Cellphone Store Limited | Information & communication | 1997 |
| THE Ceylon Transcending Private Limited | Manufacturing | 2024 |
| THE Chimneys Healthcare Partnership Limited | Financial services | 2015 |