| Surgyrex Limited | Real estate | 2017 |
| Surridge Consulting Ltd | Information & communication | 2023 |
| Sursus Ltd | Administrative & support | 2020 |
| Suruchi Technologies Ltd | Information & communication | 2013 |
| Susan @ Instock Solution Limited | Professional & scientific | 2025 |
| Susplan Ltd | Professional & scientific | 2025 |
| Sustainable Products by Design Limited | Wholesale & retail | 2022 |
| Sustainable Technical Solutions Limited | Professional & scientific | 2023 |
| Sutton Enterprises Ltd | Professional & scientific | 2025 |
| Sutton Fish and Chips Ltd | Hospitality | 2019 |
| Suya Deli Limited | Hospitality | 2023 |
| SV Care Services Limited | Health & social care | 2020 |
| SV Education Limited | Education | 2025 |
| SV Financing Limited | Real estate | 2023 |
| SV UK Group Limited | Financial services | 2023 |
| Svaarj Limited | Wholesale & retail | 2021 |
| Svaros Ltd | Professional & scientific | 2014 |
| SVU Properties Limited | Real estate | 2021 |
| SW Contractors Essex Ltd | Construction | 2018 |
| SW1 Construction Ltd | Construction | 2026 |
| Swallows Gymnastics Property Ltd | Arts & recreation | 2024 |
| Swan Compliance Ltd | Construction | 2026 |
| Swanley 1ST Health Foot Clinic Ltd | Health & social care | 2020 |
| Swati IT Consulting Private Limited | Information & communication | 2024 |
| Sweeping Fires Ltd | Administrative & support | 2026 |
| Sweet Potato TEC Ltd | Information & communication | 2014 |
| Sweet Queen Limited | Wholesale & retail | 2020 |
| Swift World Limited | Administrative & support | 2010 |
| Swiftnest Ventures Ltd | Wholesale & retail | 2024 |
| Swim Switzerland Ltd | Arts & recreation | 2023 |
| Swimming Tales Limited | Arts & recreation | 2004 |
| Swimsafe Electrical Ltd | Manufacturing | 2009 |
| Swingfield Limited | Other services | 1994 |
| Swinney Consulting Limited | Information & communication | 2009 |
| Swiss Space Ltd | Transport & logistics | 2020 |
| Switched on Media UK Ltd | Real estate | 2009 |
| SX Couriers Limited | Financial services | 2006 |
| SX Marketing Ltd | Information & communication | 2024 |
| SX Motors Ltd | Wholesale & retail | 2018 |
| SX Refurbishments Ltd | Administrative & support | 2017 |
| SXD Environmental Services Ltd | Construction | 2014 |
| Sycamore House Endearing Developments Limited | Real estate | 2010 |
| Syed Associates Ltd | Real estate | 2024 |
| Syed Muhammad ALI Raza Kazmi Ltd | Wholesale & retail | 2025 |
| Syeda's Enterprises Ltd | Hospitality | 2012 |
| Syleverse Learning Ltd | Education | 2024 |
| Sylvaa Limited | Financial services | 2025 |
| Sylversoft Limited | Information & communication | 2007 |
| Symbolic Care Group Limited | Administrative & support | 2024 |
| Symington Property Services Limited | Real estate | 2004 |
| Synaptix AI Ltd | Information & communication | 2023 |
| Synergy Automotive Parts Limited | Manufacturing | 2020 |
| Synergy Management (SE) Ltd | Professional & scientific | 2025 |
| Synergy Property Management Limited | Households | 1999 |
| Synergy Steel Structures Limited | Construction | 2015 |
| Synonymous Limited | Professional & scientific | 2021 |
| Synonymous Sport Limited | Professional & scientific | 2024 |
| Synq Recruit Ltd | Administrative & support | 2025 |
| Sysress Limited | Information & communication | 2016 |
| System Square Films Limited | Information & communication | 2014 |
| Systems Information Management Limited | Information & communication | 2023 |
| Systemsound Limited | Administrative & support | 1982 |
| Szgp Limited | Health & social care | 2024 |
| SZL Limited | Information & communication | 2010 |
| SZL Property Investments Limited | Real estate | 2022 |
| T & D Services Limited | Professional & scientific | 2015 |
| T & K International Ltd | Other services | 2015 |
| T & S Carpentry & Construction Ltd | Manufacturing | 2025 |
| T & T Global Recruitment Ltd | Administrative & support | 2018 |
| T a M Insulation Ltd | Construction | 2017 |
| T Bahadur Limited | Hospitality | 2003 |
| T Bird Plumbing and Heating Limited | Construction | 2023 |
| T Bradbury Ltd | Professional & scientific | 2015 |
| T CUT Barbers Ltd | Other services | 2025 |
| T Higdon Building Services Limited | Construction | 2011 |
| T I & H L Jopson - Trading AS CM3 Cars & Couriers Ltd | Transport & logistics | 2018 |
| T M Hughes Property Investments Ltd | Real estate | 2022 |
| T Mctaggart Limited | Health & social care | 2008 |
| T Pennack and Sons Limited | Other services | 2015 |
| T R Electrical Ltd | Construction | 2011 |
| T R Hill Investments Ltd | Real estate | 2022 |
| T Rushbrook Group Ltd | Administrative & support | 2020 |
| T W Road Haulage Ltd | Other services | 2014 |
| T W Stationers Direct Ltd | Wholesale & retail | 2019 |
| T&A Aesthetics Ltd | Health & social care | 2020 |
| T&A Universe Ltd | Construction | 2012 |
| T&G Solutions Limited | Professional & scientific | 2011 |
| T&K Holdings Ltd | Financial services | 2016 |
| T&S Consultancy Limited | Professional & scientific | 2021 |
| T&T Sons Ltd | Hospitality | 2025 |
| T&Wmeats Ltd | Wholesale & retail | 2018 |
| T. Rippon Estates Limited | Real estate | 1957 |
| T.B London Services Ltd | Professional & scientific | 2025 |
| T.E. Distribution Limited | Wholesale & retail | 2003 |
| T.E.B Mortgage Solutions Ltd | Financial services | 2021 |
| T.J. Property Maintenance Ltd | Construction | 2020 |
| T.L. Care (Havering) Holdings Limited | Financial services | 2019 |
| T.L. Care (Havering) Limited | Other services | 1996 |
| T.M. Hughes & SON Electrical Services Limited | Construction | 2018 |
| T.M. Hughes & SON GAS Services Limited | Construction | 2004 |