| Swush Solutions Ltd | Manufacturing | 2022 |
| SYA General Solutions Ltd | Education | 2022 |
| Syata Dishmaya Ltd | Professional & scientific | 2019 |
| Sybil and Co Ltd | Professional & scientific | 2020 |
| Sycamore Properties & Management Limited | Construction | 2024 |
| Sydney Food Limited | Administrative & support | 2010 |
| Sylphora Limited | Wholesale & retail | 2025 |
| Sylvia Monica Limited | Real estate | 2023 |
| Sympatheia Lettings Limited | Real estate | 2023 |
| Sympatheia Limited | Health & social care | 2023 |
| Symphony Energy Limited | Extraterritorial | 2011 |
| Symphony Environmental Limited | Manufacturing | 1994 |
| Symphony Environmental Technologies PLC | Manufacturing | 1998 |
| Symphony of Souls Harmony Initiative Limited | Education | 2025 |
| Symphony Recycling Technologies Limited | Water & waste | 2006 |
| Synb Ltd | Real estate | 2018 |
| Syndicate Sports Management Ltd | Financial services | 2025 |
| Synergise Consult Ltd | Professional & scientific | 2004 |
| Synergist Consultancy Services Ltd | Financial services | 2024 |
| Synergy Care & Support Limited | Health & social care | 2023 |
| Synergy Guards Holdings Limited | Real estate | 2026 |
| Synergy Guards UK Ltd | Administrative & support | 2006 |
| Synergy Web Services Ltd | Information & communication | 2025 |
| Synlith Ltd | Information & communication | 2025 |
| Synotica Limited | Real estate | 2024 |
| Synthesis Editorial Ltd | Professional & scientific | 2013 |
| System Test Specialists Limited | Information & communication | 2000 |
| Systems Connect Limited | Information & communication | 2000 |
| Systeq Ltd | Manufacturing | 2023 |
| T & E Builders Ltd. | Construction | 1991 |
| T Beverages Harrow Limited | Wholesale & retail | 2023 |
| T Khanbhai Limited | Professional & scientific | 2013 |
| T L Dany Estate Limited | Real estate | 2025 |
| T Lefort Carpentry Limited | Construction | 2021 |
| T M Connolly Group Ltd | Hospitality | 2018 |
| T Meads Builders Ltd | Construction | 2022 |
| T S and K Properties LLP | | 2023 |
| T Star Tech Ltd | Information & communication | 2021 |
| T Welsh Scenic Builders Limited | Information & communication | 2015 |
| T&M Productions Ltd | Information & communication | 2022 |
| T. Bland Welding Limited | Manufacturing | 2003 |
| T.G.Y. Limited | Professional & scientific | 2014 |
| T.H Carpentry & Joinery Ltd | Manufacturing | 2025 |
| T.L. Dany Guard Security and Transport Ltd | Transport & logistics | 2015 |
| T.L.K. Edwards & Sons Limited | Wholesale & retail | 1965 |
| T.L.K.Edwards(Jewellers)Limited | Wholesale & retail | 1940 |
| T2M Nationwide Limited | Real estate | 1992 |
| T2M.SWLONDON Limited | Real estate | 2015 |
| TA Media & Motion Ltd | Information & communication | 2026 |
| Taap Limited | Information & communication | 2003 |
| Tabac Limited | Construction | 2024 |
| Taha Capital Ltd | Financial services | 2014 |
| Tailored Web Limited | Information & communication | 2020 |
| Taimli Ltd | Manufacturing | 2021 |
| Taite Crown Limited | Hospitality | 2023 |
| Take a BOW Productions Ltd | Arts & recreation | 2015 |
| Talent Casting Ltd | Professional & scientific | 2024 |
| Talent Tribe Ltd | Professional & scientific | 2018 |
| Talk of the Town Productions Ltd | Arts & recreation | 2025 |
| Tally & Associates Legal Services Limited | Professional & scientific | 2025 |
| Tamar Hillspring Limited | Wholesale & retail | 2020 |
| Tamara Fitzherbert Designs Ltd | Other services | 2014 |
| Tamara Kramer Limited | Arts & recreation | 2018 |
| Tamatim Properties Ltd | Real estate | 2021 |
| Tamehaven Limited | Health & social care | 1994 |
| Tamworth Road (Hertford) Management Company Limited | Households | 2022 |
| TAN Interiors & Const. Ltd | Construction | 2017 |
| TAN Jewellery Ltd | Wholesale & retail | 2023 |
| Tana Finance Partners Limited | Professional & scientific | 2026 |
| Tangent Seven Limited | Administrative & support | 2003 |
| Tango 48 Aviation Limited | Other services | 2016 |
| Tania Cohanim Consulting Limited | Professional & scientific | 2019 |
| Tantalum Consulting Limited | Administrative & support | 2016 |
| Tantivy Court RTM Company Limited | Households | 2009 |
| Tanto Capital Partners Advisory Ltd | Professional & scientific | 2020 |
| Tanto Capital Partners Group Ltd | Professional & scientific | 2021 |
| TAO Global Limited | Real estate | 2017 |
| Tao-Ayache Consultancy Services Limited | Information & communication | 2018 |
| TAP Specialists Ltd | Administrative & support | 2025 |
| Taqwa Estates Ltd | Real estate | 2021 |
| Tarakki Consulting Limited | Information & communication | 2012 |
| Taratarat UK Limited | Professional & scientific | 2004 |
| Targetstar UK Ltd | Arts & recreation | 2024 |
| Tarm Investment Ltd | Professional & scientific | 2020 |
| Tarm Property Ltd | Real estate | 2024 |
| Taxadoo Limited | Information & communication | 2026 |
| Taxi Payments Limited | Administrative & support | 2026 |
| TAY TAR Thai Ltd | Hospitality | 2016 |
| Taylor Appleford Logistics Ltd | Transport & logistics | 2024 |
| Taylor Berlin Limited | Real estate | 2025 |
| Taylor Viney & Marlow Group Limited | Professional & scientific | 2021 |
| Taylor Viney & Marlow Limited | Professional & scientific | 2021 |
| Tbbc Ltd | Wholesale & retail | 2011 |
| Tbbc Sussex Ltd | Wholesale & retail | 2020 |
| Tbeg Holdings Limited | Financial services | 2025 |
| TBG Search Ltd | Administrative & support | 2010 |
| Tbkc (Sussex) Ltd | Wholesale & retail | 2020 |
| TBL Consulting Limited | Information & communication | 2012 |
| TBR Limited | Real estate | 2022 |
| TC Primera Limited | Professional & scientific | 2022 |