| Servo Heat Limited | Construction | 2022 |
| Seventy 3 Frames Limited | Information & communication | 2014 |
| SGV Services Ltd | Administrative & support | 2019 |
| Shadowfill Ltd | Professional & scientific | 2022 |
| Shapers (Croydon) Limited | Arts & recreation | 2007 |
| Shareframe Limited | Professional & scientific | 1993 |
| Sharm Hairdressing Ltd. | Other services | 2017 |
| Sharma IT Corporation Limited | Information & communication | 2013 |
| Shepherd Content Ltd | Information & communication | 2022 |
| Sherman Consulting Limited | Professional & scientific | 2025 |
| Sheron Trading Ltd | Wholesale & retail | 2021 |
| Shifting Notes Ltd | Information & communication | 2026 |
| Shoeb Limited | Professional & scientific | 2015 |
| Shopperhappy.Com Limited | Wholesale & retail | 2016 |
| Showleys Ltd | Wholesale & retail | 2026 |
| Siddhantha Enterprises Limited | Professional & scientific | 2020 |
| Siddhi Property Investments Ltd | Real estate | 2024 |
| Sidds Events Ltd. | Hospitality | 2024 |
| Sigma Phase Ltd | Professional & scientific | 2025 |
| Signature Waves Ltd | Wholesale & retail | 2024 |
| Siklos Limited | Professional & scientific | 2015 |
| Sikorsky Consulting Limited | Professional & scientific | 2022 |
| Silicon Lawn Limited | Administrative & support | 2016 |
| Silva Sister Limited | Other services | 2019 |
| Silverdale Development Projects Limited | Construction | 2018 |
| Silvergates Investments | Administrative & support | 2018 |
| SIM Property Limited | Real estate | 2024 |
| Simon Hudspeth Hospitality Consulting Limited | Professional & scientific | 2012 |
| Simply Padel Ltd | Arts & recreation | 2023 |
| Simplyhrsolutions Limited | Administrative & support | 2012 |
| Simulation Sales Consulting Limited | Professional & scientific | 2023 |
| Siyano G Ltd | Transport & logistics | 2017 |
| SJR Landmark 2 Limited | Real estate | 2018 |
| SJR Landmark Limited | Real estate | 2017 |
| Skaedreams Ltd | Information & communication | 2008 |
| Sky Deals Limited | Wholesale & retail | 2010 |
| Skylark Copy Limited | Professional & scientific | 2020 |
| Skyline Management Solutions Ltd | Real estate | 2024 |
| Skyrme Limited | Professional & scientific | 2020 |
| Slice & Scoop Ltd | Hospitality | 2025 |
| Slocombe Properties Limited | Real estate | 2025 |
| Slouch Candles Ltd | Other services | 2021 |
| Slough Town FC Community CIC | Arts & recreation | 2023 |
| Smaracare Ltd | Health & social care | 2018 |
| Smarter Services Ltd | Administrative & support | 2006 |
| Smith Stone Construction Ltd | Construction | 2026 |
| SMP Media Consulting Limited | Information & communication | 2017 |
| Snowman Property Services Ltd | Administrative & support | 2012 |
| Social Courage Ltd | Professional & scientific | 2024 |
| Social Hub Ltd | Information & communication | 2025 |
| Sokos Property Solutions Ltd | Real estate | 2024 |
| SOL Tour Ltd | Administrative & support | 2023 |
| Solomon House Limited | Health & social care | 2009 |
| Solulos Ltd | Extraterritorial | 2025 |
| Solus Electrical Contractors Ltd | Construction | 2023 |
| Sonder Services Limited | Transport & logistics | 2019 |
| Sophie's Sister Fine Jewellery Ltd | Wholesale & retail | 2023 |
| Sopranos Barber Walton Ltd | Other services | 2021 |
| Sourcelink Solutions Ltd | Wholesale & retail | 2025 |
| South River Asset Management Limited | Financial services | 2001 |
| South West London Urology Ltd. | Health & social care | 2008 |
| Southern Groundworks and Construction Ltd | Construction | 2022 |
| Space Landscaping Ltd | Administrative & support | 2022 |
| SPACEMAN30 Ltd | Wholesale & retail | 2023 |
| Spanish Amigos Ltd | Education | 2010 |
| Sparks & Cakes Limited | Manufacturing | 2023 |
| Spartan Security Services Ltd | Other services | 2014 |
| SPB Investment Group Ltd | Households | 2025 |
| Spcube Ltd | Information & communication | 2010 |
| Special Lift Projects International Ltd | Manufacturing | 2012 |
| Specto Limited | Other services | 2012 |
| SPESNOVA23 Limited | Professional & scientific | 2023 |
| Spire Infragen Limited | Administrative & support | 2010 |
| Spirit Labs Ltd | Information & communication | 2013 |
| Splice Music Ltd | Information & communication | 2012 |
| SPN Racing Ltd | Construction | 2016 |
| Sport Retreats Ltd | Administrative & support | 2020 |
| Spotter Golf Ltd | Professional & scientific | 2024 |
| Spriggs Estates Ltd | Real estate | 2022 |
| Sprint Script Software Limited | Information & communication | 2025 |
| Square Foot Finance Ltd | Financial services | 2021 |
| SQUARE71 Ltd | Information & communication | 2015 |
| Squidgy Bake Ltd | Manufacturing | 2022 |
| Srilasri Arul Sakthi Annai Limited | Information & communication | 2018 |
| Sroda Construction Limited | Construction | 2017 |
| Sroda Properties Limited | Real estate | 2019 |
| SRS Roofing Solutions Limited | Construction | 2020 |
| ST Martin's Maisonettes (Management) Co. Limited | Real estate | 2004 |
| ST Vincent Court (Walton on Thames) Management Company Limited | Households | 2007 |
| Stallion Holdings Ltd | Manufacturing | 2026 |
| Stalworth International Limited | Wholesale & retail | 2019 |
| Stanley Road House Ltd | Other services | 2017 |
| Staples Green Properties Unlimited | Professional & scientific | 2010 |
| Star Mode Limited | Hospitality | 2017 |
| Stature Property Group Ltd | Real estate | 2025 |
| Stay Inspired Music Limited | Arts & recreation | 2014 |
| Steady Nest Ltd | Health & social care | 2025 |
| Steels Consultancy Ltd | Professional & scientific | 2025 |
| Stefika Limited | Other services | 2021 |
| Stella Hockley Property Management Limited | Real estate | 2017 |