| Symmetry Cafe Ltd | Hospitality | 2025 |
| Symmetry Cartridges Ltd | Wholesale & retail | 2020 |
| Symmetry Property Group Ltd | Real estate | 2025 |
| Synergization Limited | Administrative & support | 2018 |
| Synergy Beauty MED UK Limited | Health & social care | 2013 |
| Synergy Retail Support Holdings Limited | Financial services | 2022 |
| Synergy Retail Support Ltd | Administrative & support | 2009 |
| Synergy Youthful Services Limited | Administrative & support | 2015 |
| Synergyshops Ltd | Wholesale & retail | 2023 |
| Synnogy Limited | Administrative & support | 2001 |
| Synpro Properties Ltd | Real estate | 2010 |
| Synt Group Limited | Manufacturing | 2016 |
| SYS3 Holdings Limited | Extraterritorial | 2016 |
| Systemastic Limited | Construction | 2003 |
| Systems Created Limited | Information & communication | 1987 |
| Systemtech Services Limited | Information & communication | 2021 |
| T & a Events Ltd | Arts & recreation | 2020 |
| T & S Wild Limited | Construction | 2008 |
| T and E Photography Ltd | Professional & scientific | 2025 |
| T Bateman Flooring Services Ltd | Construction | 2020 |
| T D Contracts Limited | Construction | 2015 |
| T D M Furniture Ltd | Wholesale & retail | 2024 |
| T D Software Services Limited | Information & communication | 2015 |
| T Glover & Sons LLP | | 2023 |
| T Hogg Plumbing and Bathrooms Ltd | Construction | 2020 |
| T K Cope Moto Limited | Wholesale & retail | 2006 |
| T L Ward Ltd | Agriculture & fishing | 2020 |
| T M Initiatives Ltd | Health & social care | 2011 |
| T M Kitchen Installations Ltd | Construction | 2020 |
| T S Roofing and Cladding Limited | Construction | 2016 |
| T Sims Property Limited | Households | 2025 |
| T&C Robertson T/A the Spinnaker Public House Ltd | Hospitality | 2026 |
| T&G Touring Limited | Professional & scientific | 2022 |
| T&H Motors Limited | Wholesale & retail | 2025 |
| T&J Fire Systems Limited | Construction | 2003 |
| T&M Hopkins Construction Ltd | Construction | 2025 |
| T&R Groundworks Ltd | Construction | 2023 |
| T-Prime Limited | Construction | 2009 |
| T. & M. Auto Electrical Co. Limited | Wholesale & retail | 1982 |
| T. W. Rogers Ltd | Construction | 2002 |
| T.B. Futures Limited | Administrative & support | 2004 |
| T.D. and A.M. Bugg (Holdings) Limited | Water & waste | 2002 |
| T.D. and A.M. Bugg Limited | Water & waste | 1993 |
| T.E.T Property Services Limited | Real estate | 2016 |
| T.M. O'Brien Limited | Other services | 2008 |
| T.R. Eagle Construction Ltd | Construction | 2006 |
| T16 Design Ltd | Professional & scientific | 2012 |
| T3 Management Limited | Professional & scientific | 2022 |
| T3F E&R Limited | Professional & scientific | 2024 |
| T5 Creative Limited | Professional & scientific | 2009 |
| T78 Limited | Professional & scientific | 2021 |
| Taaq Ltd | Wholesale & retail | 2024 |
| Taaste Ltd | Wholesale & retail | 2024 |
| Tabletop Troll Ltd | Arts & recreation | 2025 |
| Tabor Gardens Management Company Limited | Households | 2003 |
| Tabor House (Braintree) RTM Company Limited | Households | 2019 |
| TAC Healthcare Services Limited | Health & social care | 2015 |
| Tacsure Ltd | Administrative & support | 2024 |
| Tactical Bulild Limited | Construction | 2025 |
| Tadpole Contracts Limited | Information & communication | 1997 |
| Tadpole Radios Ltd | Manufacturing | 2016 |
| TAG Properties Limited | Real estate | 2001 |
| Tahtali Ltd | Information & communication | 2013 |
| Tail AI Ltd | Extraterritorial | 2024 |
| Tailored Retirement & Investment Planning Limited | Financial services | 2014 |
| Tails of Mersea Ltd | Other services | 2025 |
| Tait Mews (Maldon) Residents Company Limited | Households | 2000 |
| Taite C.I.C. | Health & social care | 2022 |
| Taiwo Ltd | Real estate | 2026 |
| Tajrockstar Ltd | Wholesale & retail | 2024 |
| TAK Smart Cleaning Company Ltd | Administrative & support | 2024 |
| Takasho UK Limited | Wholesale & retail | 2010 |
| Takforce Ltd | Administrative & support | 2024 |
| Takhar Couriers Ltd | Transport & logistics | 2019 |
| Taktic Limited | Wholesale & retail | 2021 |
| Talacq Ltd | Administrative & support | 2023 |
| Talent Events Limited | Arts & recreation | 2018 |
| TALENT4PERFORMANCE Ltd | Professional & scientific | 2015 |
| Talentix Limited | Administrative & support | 2025 |
| Talgeo Ltd | Education | 2019 |
| Talisman Logistics Limited | Transport & logistics | 2003 |
| TALK2ME International Ltd | Administrative & support | 2020 |
| Tallat Express Group Ltd | Wholesale & retail | 2025 |
| Tallchair Ltd | Households | 2016 |
| Tallyfive Ltd | Households | 2016 |
| Tamadoni Ltd | Professional & scientific | 2017 |
| Tamadoni Medical Care Ltd | Wholesale & retail | 2012 |
| Tamarinds (Colchester) Management Company Limited | Households | 2005 |
| Tambride Limited | Construction | 1987 |
| Tanbell Limited | Hospitality | 2018 |
| Tancastell Finance Limited | Professional & scientific | 2015 |
| Tangentc Limited | Information & communication | 2023 |
| Tankline Limited | Construction | 2025 |
| Tantallon Flat Management Company Limited | Households | 1982 |
| Tantalum Insights Ltd | Professional & scientific | 2024 |
| Tanya Osborn Limited | Professional & scientific | 2024 |
| Taoist TAI CHI Society of Great Britain | Education | 1991 |
| TAP Unique Interiors Ltd | Construction | 2015 |
| Taphaus Ltd | Wholesale & retail | 2025 |
| Tapori Consulting Ltd | Information & communication | 2014 |