| Seipan Holdings Limited | Financial services | 2023 |
| Selecta Playlists Ltd | Arts & recreation | 2017 |
| Selene Optical Ltd | Health & social care | 2026 |
| Selfstir Limited | Information & communication | 2013 |
| Sell My Stuff Ltd | Wholesale & retail | 2026 |
| Selmar Investments Limited | Real estate | 2021 |
| Selwin Management Limited | Households | 1993 |
| Senlife Ltd | Information & communication | 2021 |
| Sentinel Tech Ltd | Information & communication | 2017 |
| Sequoia Landscapes Ltd | Administrative & support | 2004 |
| Service Station Investments Limited | Real estate | 1953 |
| Serviceit Networking LLP | | 2012 |
| Serviq Limited | Construction | 2018 |
| Sesame SOY Ltd | Manufacturing | 2026 |
| Seth Rowden Ltd | Administrative & support | 2019 |
| Seven Hills Property Group Limited | Real estate | 2020 |
| Seventeen SIX Ltd | Professional & scientific | 2024 |
| Seventh Avondale Residents Association Limited | Households | 1986 |
| Sewa Care Ltd | Health & social care | 2023 |
| SH Makerspace Ltd | Other services | 2012 |
| SH Outdoors Ltd | Administrative & support | 2024 |
| Shadow Healthcare Ltd | Information & communication | 2026 |
| Shamley Green Stores Limited | Wholesale & retail | 2013 |
| Shanklin Court Residents Association Limited | Households | 1986 |
| Share Plan Partners Ltd | Professional & scientific | 2013 |
| Sharpe's Minibus Travel Ltd | Administrative & support | 2022 |
| Sharples-Vizard Ltd | Professional & scientific | 2025 |
| Shaw Media Limited | Information & communication | 2014 |
| Shawnigan Properties Limited | Real estate | 1961 |
| Shearforce Power Products Limited | Manufacturing | 2018 |
| Sheets Heath Woodland Limited | Households | 2022 |
| Shepherd Executive Advisory Ltd | Professional & scientific | 2026 |
| Sherene Melinda Limited | Manufacturing | 2013 |
| Shield Automotive Greased Lightning UK Ltd | Wholesale & retail | 2002 |
| Shield Integrated Solutions Ltd | Administrative & support | 2018 |
| Shield Security Services Limited | Administrative & support | 1986 |
| Shoots Garden Centres Limited | Wholesale & retail | 1991 |
| Shore Leave Productions Ltd | Information & communication | 2017 |
| Shoreman International Limited | Professional & scientific | 2014 |
| Shortest Path Limited | Information & communication | 2010 |
| Shortfield UK Limited | Professional & scientific | 2022 |
| Shorthose Consulting Limited | Professional & scientific | 2018 |
| Shorthose Investments Ltd | Real estate | 2019 |
| Shplanning Ltd | Professional & scientific | 2025 |
| SHU DA Living Limited | Wholesale & retail | 2016 |
| Siam Oishi Limited | Hospitality | 2020 |
| Sighh Designs Limited | Wholesale & retail | 2015 |
| Signaliq Limited | Professional & scientific | 2026 |
| Signetor Limited | Professional & scientific | 2017 |
| Signpostme Limited | Other services | 2026 |
| Sihm Ltd | Wholesale & retail | 2023 |
| Silberhorn Chocolate Company Ltd | Manufacturing | 2025 |
| Silberhorn Management Ltd | Information & communication | 2020 |
| Silberhorn Media Capital Ltd | Information & communication | 2020 |
| Silberhorn Media Group Ltd | Financial services | 2025 |
| Silberhorn Pictures Ltd | Information & communication | 2022 |
| Silkroute Worldwide Limited | Administrative & support | 2009 |
| Silver Rivers Limited | Construction | 2005 |
| Silverback Safety Services Ltd. | Professional & scientific | 2018 |
| Silverbeak Limited | Extraterritorial | 2021 |
| Silvercross Properties (NO.2) Ltd. | Real estate | 2000 |
| Silvercross Properties (NO.3) Limited | Real estate | 2003 |
| Silvercross Properties Limited | Real estate | 1999 |
| Simaal Ltd | Information & communication | 2016 |
| Simbiosys Limited | Extraterritorial | 2026 |
| Simi Connect Ltd | Wholesale & retail | 2019 |
| Simi Lettings Ltd | Real estate | 2020 |
| Simmons Interior Supply Ltd | Wholesale & retail | 2024 |
| Simon Bevan Limited | Professional & scientific | 2007 |
| Simon English Associates Limited | Real estate | 2009 |
| Simon Marshall Holdings Limited | Real estate | 2017 |
| Simon Pure Ltd | Manufacturing | 2003 |
| Simple Van Signs Limited | Professional & scientific | 2026 |
| Simpleworking Limited | Real estate | 2020 |
| SIMPLIC8 Limited | Professional & scientific | 2017 |
| Simplify Claims Ltd | Extraterritorial | 2018 |
| Simsonic Limited | Extraterritorial | 2025 |
| Sinesis Limited | Professional & scientific | 2024 |
| Sing Limited | Information & communication | 2023 |
| Sipologist Social Limited | Other services | 2016 |
| Sipsup Limited | Manufacturing | 2018 |
| Sipsync Ltd | Wholesale & retail | 2024 |
| SIR Ivor Racing Limited | Arts & recreation | 2008 |
| Siscien Lifesciences Ltd | Administrative & support | 2019 |
| Sisterstory Limited | Wholesale & retail | 2020 |
| Site Logistics Ltd | Administrative & support | 2004 |
| Site Logistics New Ltd | Professional & scientific | 2009 |
| Sitefirst Property Management Limited | Households | 1989 |
| Siteready Property Management Limited | Households | 1992 |
| Sitespray Limited | Construction | 2010 |
| Sitnt Limited | Information & communication | 2014 |
| Sitwell Advisory Ltd | Professional & scientific | 2024 |
| SIX Degrees Labs Limited | Information & communication | 2018 |
| SIX One Enterprises Limited | Wholesale & retail | 2014 |
| SIX Sixes Design Limited | Information & communication | 2014 |
| SIX Steps Limited | Professional & scientific | 2026 |
| Sixtytoforty Limited | Information & communication | 2015 |
| SJ Mckinlay Consulting Ltd | Administrative & support | 2025 |
| Sjms Limited | Wholesale & retail | 2004 |
| SJS Planning Limited | Professional & scientific | 2012 |