| Sunspa UK Limited | Wholesale & retail | 2006 |
| Super Banana Limited | Information & communication | 2025 |
| Supernastics Ltd | Education | 2019 |
| Supersize Ltd | Arts & recreation | 2020 |
| Superwatermelon Limited | Information & communication | 2015 |
| Supreme Event Logistics Ltd | Real estate | 2019 |
| Surgiqa Consulting Ltd | Professional & scientific | 2024 |
| Survey Review Limited | Information & communication | 2006 |
| Susan Hill FP Ltd | Financial services | 2016 |
| Susan Newton Consulting Limited | Professional & scientific | 2013 |
| Sushi at Home Limited | Wholesale & retail | 2011 |
| SUSTAIN24 Care Ltd | Health & social care | 2022 |
| Sustainable X Limited | Professional & scientific | 2018 |
| Sutton Grange (ST. Albans) Management Limited | Households | 1992 |
| SV Management Company Limited | Real estate | 2011 |
| SW Process Engineering Ltd | Professional & scientific | 2011 |
| Swak Golf Ltd | Wholesale & retail | 2024 |
| Swallowturn Ltd | Administrative & support | 2023 |
| Swan House Management Services Limited | Real estate | 2023 |
| Swannjohns Ltd | Professional & scientific | 2025 |
| SWC FF1 Cetp V Nominees Limited | Financial services | 2022 |
| Sweet Briar Mews Management Company Limited | Households | 2016 |
| Sweet Punch Limited | Information & communication | 2023 |
| Swheatley Consultants Ltd | Professional & scientific | 2022 |
| Swift Security Group Ltd | Administrative & support | 2025 |
| Swiftcleanings Limited | Administrative & support | 2017 |
| Swiftline Distribution Ltd | Wholesale & retail | 2024 |
| Swimtime Southeast Limited | Education | 2017 |
| Swimtime Surrey Limited | Education | 2017 |
| Swinbank Family Partnership LLP | | 2022 |
| Swizzoo Limited | Wholesale & retail | 2026 |
| SWJ UK Ltd | Wholesale & retail | 2008 |
| SWK Services Limited | Administrative & support | 2016 |
| SWK Solutions Limited | Professional & scientific | 2011 |
| SXB Ltd | Professional & scientific | 2025 |
| SY Hair Limited | Other services | 2025 |
| Sycamore Capital (Italy) Limited | Other services | 2019 |
| Sycamore Capital (Norfolk) Limited | Real estate | 2022 |
| Sycamore Capital Limited | Professional & scientific | 2010 |
| Sycamore Drive Limited | Households | 2015 |
| Sycamore Solar Limited | Other services | 2020 |
| Sydney Black Charitable Trust(The) | Health & social care | 1949 |
| Syhlet Spice Ltd | Hospitality | 2022 |
| Sylheti Kitchen Ltd | Hospitality | 2025 |
| Sylv Limited | Manufacturing | 2024 |
| Symposia U.K. Limited | Other services | 2021 |
| Synapse Medical Community Interest Company | Health & social care | 2021 |
| Synergy Enterprises International Limited | Information & communication | 2017 |
| Synergy Financial Products Limited | Professional & scientific | 1984 |
| Synergy Nominees Limited | Administrative & support | 2013 |
| Synero Consulting Ltd | Professional & scientific | 2025 |
| Syso Photographic Ltd | Other services | 2015 |
| Sytex Services Limited | Transport & logistics | 2022 |
| T & a Taylor Limited | Hospitality | 2023 |
| T & Allushi Property Ltd | Real estate | 2023 |
| T & B (Contractors) Holdings Limited | Financial services | 2013 |
| T & B (Contractors) Limited | Construction | 1982 |
| T Catering Ltd | Hospitality | 2026 |
| T D Bridger Limited | Manufacturing | 1941 |
| T F Chauffeur Limited | Transport & logistics | 2014 |
| T K Scenery Ltd | Information & communication | 2019 |
| T M Installations Ltd | Construction | 2014 |
| T Mccall Holdings Limited | Financial services | 2025 |
| T Moulton Consulting Limited | Professional & scientific | 2026 |
| T&B (Contractors) Group Holdings Limited | Financial services | 2026 |
| T&M Dream Investments Ltd | Real estate | 2024 |
| T&M Dream Properties Ltd | Real estate | 2023 |
| T-Kun Ltd | Professional & scientific | 2020 |
| T. Taylor & Sons (Herts) LLP | | 2021 |
| T.C. Fensom & SON Limited | Professional & scientific | 2006 |
| T.S.G. Carpentry Limited | Construction | 2015 |
| TA Sports Services Ltd | Education | 2015 |
| Tabard (2024) Limited | Arts & recreation | 2024 |
| Tactile Media Ltd | Information & communication | 2021 |
| Tahir Waqas Construction UK Ltd | Construction | 2026 |
| Tailored 33 Ltd | Manufacturing | 2023 |
| Taiyeb Properties Ltd | Real estate | 2022 |
| Talaris Limited | Professional & scientific | 2021 |
| Talent Dimensions Limited | Professional & scientific | 2016 |
| Talent Tomorrow Ltd. | Other services | 2015 |
| Talent X Academy Limited | Arts & recreation | 2021 |
| Talent X Ltd | Professional & scientific | 2021 |
| Talentaire Ltd | Administrative & support | 2025 |
| Talentinvestpro Ltd | Administrative & support | 2023 |
| Talex (UK) Ltd | Administrative & support | 2002 |
| Talk Financial Group Ltd | Financial services | 2024 |
| Tallbody Associates Ltd | Professional & scientific | 2004 |
| Tamahoe Limited | Administrative & support | 2010 |
| Tamar Computer Services Limited | Information & communication | 1993 |
| Tampa Bay Properties Limited | Real estate | 1986 |
| Tandyl Engineering Limited | Other services | 2010 |
| Tankerfield Place Management Limited | Households | 1980 |
| Tannahill Productions Ltd | Information & communication | 2020 |
| Tanner Pharma UK Limited | Wholesale & retail | 2015 |
| Tannerlac UK Limited | Wholesale & retail | 2016 |
| Tanthaimassagetherapy Ltd | Other services | 2026 |
| Tapping Into Your Big Vision Limited | Professional & scientific | 2016 |
| Tareeq UL Sunnah Tours Ltd | Administrative & support | 2025 |
| Targan Systems Ltd | Information & communication | 2025 |
| Tarma Software Research Ltd | Information & communication | 2014 |