| Shiloh & Isaac Ltd | Health & social care | 2015 |
| Ship Safe Training Group Ltd. | Transport & logistics | 1980 |
| Shipa Property Investments Ltd | Real estate | 2026 |
| Ships Electronic Services Limited | Manufacturing | 1974 |
| Shipservthames Limited | Transport & logistics | 2015 |
| Shiva Venkata Laxmi Limited | Wholesale & retail | 2025 |
| Shoey's Scaffolding Services Ltd | Construction | 2020 |
| Sholeri Ltd | Health & social care | 2022 |
| Shootsnbloom Ltd | Wholesale & retail | 2025 |
| Shoplink (PVT) Limited | Information & communication | 2024 |
| Shorts Reach Management Company Limited | Households | 1987 |
| Shower Seal (UK) Ltd | Other services | 2012 |
| Shower Wheels UK Ltd | Extraterritorial | 2021 |
| Shozna Rochester Ltd | Hospitality | 2016 |
| Shri Gmcc Limited | Health & social care | 2018 |
| Shukalo a Ltd | Transport & logistics | 2025 |
| Shukublai Business Enterprise Ltd | Transport & logistics | 2024 |
| Shunxin Shunyi Limited | Wholesale & retail | 2026 |
| Shōten Limited | Professional & scientific | 2025 |
| SI WHY Ltd | Real estate | 1994 |
| Sibs Tunes Vinyl Records Ltd | Wholesale & retail | 2024 |
| Sicame Electrical Developments Limited | Extraterritorial | 1961 |
| Sicame Electrical Distribution Limited | Extraterritorial | 2002 |
| Sight & Uhthers Ltd | Health & social care | 2015 |
| Sigma Finance Systems Limited | Information & communication | 2018 |
| Sigma Scaffolding and Rigging Ltd | Construction | 2024 |
| Signature Associates Ltd | Other services | 2022 |
| Signet Property Management Ltd | Households | 2024 |
| Signum International Ltd | Information & communication | 1998 |
| Sikh Store Ltd | Wholesale & retail | 2024 |
| Silver Line Advanced Technologies Ltd | Professional & scientific | 2020 |
| Silver Star Rentals Ltd | Hospitality | 2013 |
| Silverlined Limited | Information & communication | 2013 |
| Silverstone Oasis CIC | Health & social care | 2025 |
| SIM & Alex Ltd | Transport & logistics | 2025 |
| SIM Estate Ltd | Real estate | 2018 |
| Simbin Studios UK Limited | Information & communication | 2016 |
| Simiot Limited | Information & communication | 2022 |
| Simmons (U.K.) Limited | Extraterritorial | 1995 |
| Simmons Bedding Limited | Extraterritorial | 1993 |
| Simmons Consulting Ltd | Information & communication | 2022 |
| Simmons Locations Limited | Administrative & support | 2014 |
| Simple Automation Solutions Ltd | Professional & scientific | 2021 |
| Simple Properties Ltd | Real estate | 2020 |
| Simplistic Food & Events Ltd | Hospitality | 2020 |
| Simplistic Safety Solutions Limited | Professional & scientific | 2013 |
| Simply Electrical and Renewables Ltd | Construction | 2025 |
| Simply Good Governance Limited | Professional & scientific | 2024 |
| Simply SAP Limited | Professional & scientific | 2026 |
| Simpson & Owen Carriages Limited | Wholesale & retail | 2025 |
| Simpson Baillie (Marine) Group Limited | Professional & scientific | 2025 |
| Simpson Baillie Group Limited | Professional & scientific | 2011 |
| Simran Properties Limited | Administrative & support | 2012 |
| Singapora Limited | Hospitality | 1993 |
| Singhs Coffee Ltd | Wholesale & retail | 2022 |
| Single-Speed Ltd | Information & communication | 2014 |
| Sini Ltd | Wholesale & retail | 2024 |
| SIP and Scoff Ltd | Extraterritorial | 2014 |
| SIR Evelyn Road (Rochester) Limited | Households | 2008 |
| Siris Business Consortium (Kent) Ltd | Other services | 2022 |
| Sirkunz Ventures Limited | Health & social care | 2014 |
| Sirm Solutions Ltd | Information & communication | 2025 |
| Sisu Fitness Education Ltd | Education | 2023 |
| Sisu Fitness Limited | Arts & recreation | 2017 |
| Sita Transport Ltd | Transport & logistics | 2026 |
| Sitareshine Ltd | Wholesale & retail | 2021 |
| Site Glass Southern Limited | Manufacturing | 2002 |
| Sivertin Limited | Real estate | 2024 |
| Sivotel Ltd | Information & communication | 2020 |
| SIX Bells Cliffe Ltd | Hospitality | 2019 |
| SJ Baber Ltd | Professional & scientific | 2025 |
| SJ Developments (South East) LLP | | 2006 |
| SJ Sparks Ltd | Construction | 2026 |
| SJB Engineering Solutions Ltd | Manufacturing | 2024 |
| Sjlb Scaffolding Services Ltd | Construction | 2024 |
| Sjlk Construction Group Ltd | Construction | 2026 |
| SJS Scaffolding Ltd | Construction | 2024 |
| SK Buildworks Limited | Construction | 2026 |
| SKH Foods Limited | Hospitality | 2018 |
| Skilton Wealth Group Limited | Professional & scientific | 2021 |
| Skilton Wealth Management Limited | Financial services | 2013 |
| Skin Body Soul Laser Clinic Limited | Other services | 2021 |
| Skinlush by Abby Ltd | Other services | 2019 |
| Skinners Security Systems Ltd | Administrative & support | 2022 |
| Skinonluc Ltd | Health & social care | 2024 |
| Skip Hire Medway Limited | Extraterritorial | 2018 |
| Skippixel Ltd | Information & communication | 2026 |
| SKT Management Limited | Real estate | 2025 |
| Skua Technical Ltd | Professional & scientific | 2024 |
| Skudzinski Engineering Limited | Professional & scientific | 2018 |
| SKV Food House Group Ltd | Hospitality | 2024 |
| Skyglo Consulting Ltd | Professional & scientific | 2013 |
| Skyglo Global Ltd | Wholesale & retail | 2022 |
| Skyglo Ltd | Real estate | 2020 |
| Skyhold Ltd | Financial services | 2025 |
| Skyie Global Accountants and Business Advisors Ltd | Professional & scientific | 2026 |
| Skyie Global Financial Advisors Ltd | Financial services | 2025 |
| Skyie Global Immigration Advisors Ltd | Professional & scientific | 2024 |
| Skyie Global Infotech Ltd | Professional & scientific | 2026 |
| Skyie Global Technologies Ltd | Information & communication | 2024 |