| Southall Holiday Limited | Transport & logistics | 2002 |
| Southall Tour & Travel Ltd | Transport & logistics | 2002 |
| Southcroft (Forest) Limited | Extraterritorial | 2012 |
| Southern Pump Service Engineering Limited | Construction | 2004 |
| Southside Block Management Ltd | Households | 2015 |
| Southwood Research Ltd | Professional & scientific | 2016 |
| Sovereign Quay 25 Ltd | Real estate | 2025 |
| SP Direct Limited | Professional & scientific | 2020 |
| Spa House (Health and Beauty) Limited | Extraterritorial | 2005 |
| Spaceonly Installations Limited | Construction | 2012 |
| Spaceprivate Residents Management Limited | Real estate | 1988 |
| Spaghetti Limited | Administrative & support | 2003 |
| Spark Coach Ltd | Administrative & support | 2023 |
| Spark Media Partners Limited | Information & communication | 2013 |
| Sparky GAV Limited | Construction | 2007 |
| Sparky Phase Limited | Information & communication | 2017 |
| Spatiq Ltd | Information & communication | 2026 |
| Special Projects Studio Limited | Professional & scientific | 2014 |
| Special Transport & Security Ltd | Other services | 2023 |
| Specialist Surgical Care Limited | Health & social care | 2012 |
| Spectrum Consulting Ltd | Professional & scientific | 2008 |
| Spennybarn Limited | Agriculture & fishing | 2014 |
| Spherical Design Limited | Professional & scientific | 2022 |
| Sphirra Ltd | Administrative & support | 2016 |
| Spice Accounts Limited | Information & communication | 2010 |
| Spice Kitchen 1 Ltd | Hospitality | 2025 |
| Spinney Lane Association Limited | Households | 1981 |
| Spiral Stabilization Ltd | Other services | 2015 |
| Spirit Within CC Limited | Manufacturing | 2025 |
| Splicer Limited | Information & communication | 2011 |
| Sport Options Limited | Administrative & support | 2010 |
| Sportingclass (2010) Limited | Other services | 2010 |
| Spouse Force CIC | Administrative & support | 2022 |
| Springer Sportshorses Ltd | Other services | 2018 |
| Springfield Creative Ltd | Information & communication | 2013 |
| Springside Limited | Professional & scientific | 2006 |
| Springwell Property Investments Limited | Real estate | 2021 |
| Sprudl Europe Ltd | Administrative & support | 2024 |
| Sprunt Solutions Limited | Construction | 2003 |
| Square Mile Asset Management Limited | Financial services | 2004 |
| Square Mile Tax Management Limited | Financial services | 2012 |
| Squarecherries Ltd | Information & communication | 2015 |
| SR27 Limited | Real estate | 2023 |
| Srbg Spice Ltd | Wholesale & retail | 2025 |
| Srbl Traffic Ltd | Construction | 2023 |
| SRI Sailee Limited | Information & communication | 2014 |
| Srisan Properties Limited | Real estate | 2018 |
| SRM Developments Limited | Real estate | 2016 |
| SSG Teamwear Limited | Wholesale & retail | 2023 |
| Ssnfs Limited | Wholesale & retail | 2020 |
| SSP Medical Ltd | Health & social care | 2013 |
| Sspalm Community CIC | Professional & scientific | 2026 |
| SSQ Group Trustco Limited | Extraterritorial | 2022 |
| ST Helena 2023 | Arts & recreation | 2023 |
| ST Lawrence Group Limited | Hospitality | 2016 |
| ST Marcel Ltd | Information & communication | 2005 |
| ST Nicholas Estate Trading Ltd | Agriculture & fishing | 2026 |
| ST Peters Pilgrimages Limited | Administrative & support | 2016 |
| ST Stephen's Green Management Ltd | Real estate | 2026 |
| ST. Kilda Freehold Limited | Households | 1995 |
| ST. Mary's Courtyard (HAM) Residents Association Limited | Real estate | 1989 |
| ST. Paul's Court (Hounslow) Limited | Households | 1977 |
| Stack Developments Limited | Construction | 2004 |
| STAFF2U Ltd | Administrative & support | 2021 |
| Stafford Associates Limited | Administrative & support | 2019 |
| Stage Financial Limited | Financial services | 2017 |
| Stainswick Limited | Households | 2021 |
| Stajl Limited | Professional & scientific | 2022 |
| Stakes Hill Cottages Management Company Limited | Households | 2021 |
| Staley Holdings Limited | Real estate | 2017 |
| Staleycorp Limited | Administrative & support | 2017 |
| Stamshaw Consulting Ltd | Information & communication | 2023 |
| Stansfield Estates & Properties Ltd | Real estate | 2026 |
| Stape Online Ltd | Information & communication | 2025 |
| Star Massage & Spa Ltd | Health & social care | 2025 |
| Starlingsby Ltd | Construction | 2025 |
| Starsight Communications Ltd | Professional & scientific | 2021 |
| Steadfast Maintenance Company Limited | Construction | 1983 |
| Steam & Salt Limited | Other services | 2025 |
| Steel Windows Workshop Limited | Construction | 2019 |
| Stefano Marinaz Landscape Architecture Ltd | Other services | 2012 |
| Stelmaro Properties Limited | Real estate | 2002 |
| Stemnotes Ltd | Information & communication | 2025 |
| Stepchange Coaching Ltd | Administrative & support | 2013 |
| Stephanie Beecroft Ltd | Manufacturing | 2022 |
| Stephen COX NDT Ltd | Professional & scientific | 2014 |
| Stephen Varney Associates Limited | Professional & scientific | 2004 |
| Sterling & Co Group Ltd | Financial services | 2025 |
| Sterling and Templar Limited | Professional & scientific | 2019 |
| Sterling Bridge BKW Ltd | Wholesale & retail | 2026 |
| Sterner Consulting Limited | Information & communication | 2004 |
| Stest Limited | Information & communication | 2005 |
| Steve Hill Consultancy Limited | Professional & scientific | 2003 |
| Steve Jones Bathrooms Ltd | Construction | 2026 |
| Steve Smithwick Scenery Limited | Information & communication | 2011 |
| Steven Chilton Architects Limited | Professional & scientific | 2014 |
| Steven Morgan Logistics Ltd | Construction | 2024 |
| Steven Shorter Ltd | Administrative & support | 2016 |
| Sting Creative Limited | Extraterritorial | 2010 |
| Stitchnfix Ltd | Other services | 2020 |