| Saynomore Investments Limited | Professional & scientific | 1998 |
| SC Festivals & Events Ltd | Arts & recreation | 2018 |
| Schocross Associates Limited | Information & communication | 2004 |
| Scion Systems Ltd | Information & communication | 2017 |
| Sclero Proteins Ltd | Manufacturing | 2025 |
| SCN Technical Services Limited | Professional & scientific | 2008 |
| Score Q Limited | Information & communication | 2025 |
| Scotia GAS Networks Limited | Professional & scientific | 2003 |
| Script Technology Recruitment Solutions Ltd | Administrative & support | 2024 |
| SDB Ltd | Professional & scientific | 2020 |
| Sdkj Care Services Limited | Health & social care | 2018 |
| Seavolution Limited | Manufacturing | 2005 |
| Secret of GOD Covenant ARK Church Int'L CIC | Other services | 2026 |
| Security Systems Electrical Limited | Administrative & support | 1997 |
| Sercl Medical Ltd | Health & social care | 2011 |
| Serendipity Coffee Company Limited | Hospitality | 2015 |
| Serendipity KID Co Ltd | Hospitality | 2019 |
| Serratus Group Ltd | Professional & scientific | 2023 |
| Servantis Group Ltd | Real estate | 2026 |
| Servicsters Ltd | Wholesale & retail | 2025 |
| Seven Locations Ltd | Water & waste | 2023 |
| Seven Sins Tattoo Limited | Other services | 2013 |
| Sevenoaks SPV Ltd | Real estate | 2025 |
| SGF Construction (UK) Limited | Construction | 2013 |
| SGN Belvedere Limited | Real estate | 2018 |
| SGN Brighton Limited | Real estate | 2018 |
| SGN Commercial Services Limited | Administrative & support | 2006 |
| SGN Connections Limited | Energy | 2005 |
| SGN Contracting Limited | Administrative & support | 2005 |
| SGN Crayford Limited | Real estate | 2022 |
| SGN Croydon Limited | Construction | 2021 |
| SGN Epsom Limited | Real estate | 2018 |
| SGN Evolve Network Ltd | Energy | 2013 |
| SGN Futures (H100) Limited | Construction | 2021 |
| SGN Futures Limited | Financial services | 2021 |
| SGN GAS to Grid PROJECTCO1 Limited | Energy | 2023 |
| SGN Greenwich Limited | Real estate | 2018 |
| SGN Heat Networks Limited | Administrative & support | 2021 |
| SGN Lessona Limited | Financial services | 2018 |
| SGN Midco Limited | Financial services | 2017 |
| SGN Motspur Park Limited | Real estate | 2018 |
| SGN Old Kent Road Limited | Real estate | 2018 |
| SGN Place Limited | Financial services | 2018 |
| SGN Pledgeco Limited | Financial services | 2017 |
| SGN Property Holdings Limited | Real estate | 2018 |
| SGN Property Services Limited | Real estate | 2018 |
| SGN Rotherhithe Holdco Limited | Financial services | 2020 |
| SGN Rotherhithe Limited | Real estate | 2018 |
| SGN Silvertown LLP | | 2022 |
| SGN Smart Limited | Energy | 2005 |
| SGN Southampton Limited | Real estate | 2018 |
| SH Resources Limited | Other services | 2024 |
| Shade Sails Limited | Manufacturing | 2003 |
| Shaheen Faisal & Brothers Ltd | Real estate | 2016 |
| Shanks Holdings Ltd | Financial services | 2025 |
| Sharpbrickwork Ltd | Construction | 2018 |
| Shaun Monnery Associates Limited | Transport & logistics | 2011 |
| Shaws Building & Decorating Limited | Construction | 2018 |
| Shayam Limited | Wholesale & retail | 2020 |
| SHB Business Limited | Hospitality | 2023 |
| Sheet Shield Ltd | Manufacturing | 2026 |
| Shepherd's Cask Ltd | Arts & recreation | 2024 |
| Sherazi Sons Limited | Wholesale & retail | 2025 |
| Shiners Cleaning Contractors Limited | Administrative & support | 2002 |
| Ship N Shop Online Ltd | Information & communication | 2024 |
| Shipley Bridge Garage Limited | Wholesale & retail | 1997 |
| Shiva Soft Solutions Limited | Information & communication | 2015 |
| Showmans Transport Limited | Wholesale & retail | 1999 |
| Showtan Ltd | Extraterritorial | 2013 |
| Shriubs Ltd | Construction | 2023 |
| Siangeva Accommodation Ltd | Real estate | 2023 |
| Siel (UK) Limited | | 1983 |
| Siena Motors Ltd | Wholesale & retail | 2017 |
| Silk Syndicate Ltd | Information & communication | 2025 |
| Silva & Ward Ltd | Real estate | 2024 |
| Silver Birches Lettings Ltd | Real estate | 2025 |
| Silver Lining Actuarial Models Ltd | Financial services | 2011 |
| Simple Bridge Finance Limited | Financial services | 2023 |
| Simpletee Ltd | Wholesale & retail | 2025 |
| Sinat Ltd | Health & social care | 2013 |
| Sisaru Ltd | Wholesale & retail | 2024 |
| Siscon Controls Ltd | Construction | 2023 |
| Sixan Psychological Services Ltd | Health & social care | 2024 |
| SJ Equestrian Transport Ltd | Transport & logistics | 2024 |
| SK Building Solutions Ltd | Construction | 2025 |
| Skion Properties PVT Ltd | Real estate | 2026 |
| Skion Solutions PVT Limited | Information & communication | 2017 |
| SKS Cleaning Solutions Ltd | Administrative & support | 2011 |
| Skyline Lifting & Safety Ltd | Professional & scientific | 2017 |
| Slipstream Property Limited | Real estate | 2025 |
| SM Electrical Services Limited | Construction | 2016 |
| SM Horley Ltd | Hospitality | 2024 |
| Smallfield Football Club Holdings Ltd | Arts & recreation | 2024 |
| Smart Recruit IT Ltd | Administrative & support | 2023 |
| Smart Space Creation Ltd | Construction | 2014 |
| Smartana Ltd | Professional & scientific | 2013 |
| Smartlink Properties Ltd | Real estate | 2024 |
| SMS Building Supplies Limited | Wholesale & retail | 2021 |
| SMS Floors Ltd | Construction | 2023 |
| SN Professional Services Limited | Professional & scientific | 2018 |