| Symphony in Design Ltd | Manufacturing | 2017 |
| Synchronised Logical Solutions Limited | Information & communication | 2007 |
| Syndicate West Ltd | Professional & scientific | 2012 |
| Synectica Limited | Information & communication | 1996 |
| Synergie Solutions (UK) Ltd | Administrative & support | 2004 |
| Synergy Global Financial Solutions Ltd | Professional & scientific | 2025 |
| SYR Capital Ltd | Wholesale & retail | 2026 |
| Syracuse Partners LLP | | 2013 |
| Systech Technologies Limited | Information & communication | 2014 |
| System Plant Ltd | Administrative & support | 2023 |
| Systems UKI Limited | Information & communication | 2026 |
| Systemsoundandlighting Limited | Administrative & support | 2026 |
| T & G Collections Ltd | Wholesale & retail | 2015 |
| T Builder Ltd | Construction | 2025 |
| T Clark Services Limited | Construction | 2009 |
| T R J Builder Limited | Construction | 2017 |
| T Walker Building Ltd | Construction | 2021 |
| T&J Go Construction Ltd | Financial services | 2019 |
| T-Bag Designs UK Limited | Extraterritorial | 2004 |
| T. Cribb & Sons (2016) LLP | | 2016 |
| T. Cribb & Sons Limited | Other services | 2001 |
| T. James Properties Ltd | Real estate | 2023 |
| T. Tovey Limited | Wholesale & retail | 2008 |
| T.Cribb & Sons (Willows) Limited | Other services | 1997 |
| T.E.T Construction Ltd | Construction | 2025 |
| T.H. Peddler Ltd | Wholesale & retail | 2014 |
| T.R Advisory Services Ltd | Professional & scientific | 2024 |
| TA Property Group Limited | Real estate | 2021 |
| TA Property Investments Ltd | Real estate | 2011 |
| Ta-De London Limited | Financial services | 2024 |
| Taak Enterprise Ltd | Real estate | 2026 |
| Tabil Limited | Real estate | 2015 |
| Tablit Solutions Ltd | Information & communication | 2015 |
| TAD Media Ltd | Information & communication | 2019 |
| TAF Service Ltd | Real estate | 2014 |
| Tahoora’S Kitchen Ltd | Hospitality | 2023 |
| TAJ Foods Limited | Manufacturing | 2006 |
| Taketheshot Limited | Professional & scientific | 2021 |
| Talent Construction Limited | Construction | 2022 |
| TALENT365.IO Ltd | Administrative & support | 2022 |
| Talenttree UK Ltd | Administrative & support | 2025 |
| Talia RAE Music Limited | Arts & recreation | 2023 |
| Talicia Ltd | Real estate | 2024 |
| Talkin' Ltd | Other services | 2012 |
| Tallie Enterprise Ltd | Hospitality | 2024 |
| Tamira Limited | Professional & scientific | 2015 |
| Tams Asset & Property Management Ltd | Real estate | 2024 |
| Tams Medical Services Ltd | Health & social care | 2018 |
| Tandoori Lounge Limited | Hospitality | 2016 |
| Tangible Assets Ltd | Real estate | 2021 |
| Tanglewood Cattery Ltd | Other services | 2025 |
| Tank Puffin (Wholesale) Limited | Wholesale & retail | 2014 |
| Tanya's Tickets Limited | Wholesale & retail | 2022 |
| TAP Drinking Ltd | Hospitality | 2024 |
| TAP Eating Ltd | Hospitality | 2024 |
| TAR Haulage Limited | Transport & logistics | 2022 |
| Tardis Productions Ltd | Arts & recreation | 2017 |
| Tarlight Properties Limited | Construction | 1982 |
| Tarot by E-Mail Limited | Administrative & support | 2014 |
| Tasa Investments Ltd | Financial services | 2015 |
| Tasar Properties LLP | | 2017 |
| Taste of India (Brighton) Limited | Hospitality | 2016 |
| Tate Assets Ltd | Administrative & support | 2025 |
| Tate INV Ltd | Real estate | 2018 |
| Tate Ventures Ltd | Information & communication | 2012 |
| Taylor-Obasi Consultancy Ltd | Professional & scientific | 2025 |
| Taylorhawkeventures Ltd | Manufacturing | 2024 |
| Taylormade Secure Solutions Limited | Administrative & support | 2007 |
| TBS Service Ltd | Information & communication | 2013 |
| TC System Installation Ltd | Other services | 2014 |
| TCH Builders Ltd | Construction | 2017 |
| Tcook Consulting Ltd | Administrative & support | 2017 |
| TCS Exhumation Services Limited | Other services | 2006 |
| TD Sports (UK) Ltd | Arts & recreation | 2016 |
| Teacher Pathways Limited | Administrative & support | 2025 |
| Teacherhead Consulting Limited | Administrative & support | 2017 |
| Teal Communications Limited | Other services | 2017 |
| Teamworkh&C Limited | Administrative & support | 2017 |
| Tebbutts Road Ltd | Real estate | 2026 |
| Tech-Ed-Ex Ltd | Information & communication | 2021 |
| TECH4UK Limited | Information & communication | 2016 |
| Techappy Ltd | Information & communication | 2017 |
| Technical Architecture Design Ltd | Professional & scientific | 2018 |
| Technical Environmental Solutions Limited | Professional & scientific | 2012 |
| Technicalways Limited | Information & communication | 2021 |
| Technology Warehouse Limited | Administrative & support | 2009 |
| Techyeti Ltd | Administrative & support | 2024 |
| Tekbase IT Solutions Ltd | Information & communication | 2019 |
| Tekgie Solutions Limited | Other services | 2021 |
| Telugu Community of United Kingdom (Tcuk) | Information & communication | 2019 |
| Ternrock 2 Limited | Real estate | 2019 |
| Ternrock Limited | Construction | 2016 |
| Terry Junior Jack Skinner Ltd | Extraterritorial | 2022 |
| Tested Electrical Services Limited | Other services | 2016 |
| Testing and Training Experts Ltd | Professional & scientific | 2024 |
| TFC Compliance Ltd | Professional & scientific | 2023 |
| TGC Zone Plus Ltd | Water & waste | 2025 |
| TGE Subcontractor Ltd | Construction | 2021 |
| TGG Investments Ltd | Real estate | 2019 |
| TGL Labs Limited | Professional & scientific | 2022 |