| Shepherds Residents Company Limited | Households | 1988 |
| Sheridan Jones Ltd | Administrative & support | 2016 |
| Shezres Ltd | Real estate | 2018 |
| Shielded Limited | Information & communication | 2013 |
| Shimba Properties Ltd | Real estate | 2020 |
| Shivtransport Ltd | Transport & logistics | 2019 |
| Shoots Plants Ltd | Wholesale & retail | 2020 |
| Shreeji Infotech Ltd | Information & communication | 2004 |
| Shreekala Limited | Arts & recreation | 1995 |
| Shrop EYE Clinic Ltd | Health & social care | 2018 |
| Shtick Films Ltd | Information & communication | 2026 |
| SIA Kichens Limited | Wholesale & retail | 2020 |
| Siana Holdings Limited | Real estate | 2017 |
| SID Trade Ltd | Wholesale & retail | 2019 |
| Signature Building and Roofing Ltd | Construction | 2025 |
| Signature Transportation Ltd | Transport & logistics | 2026 |
| Silver Concept Limited | Construction | 2006 |
| SILVERO2 Ltd | Administrative & support | 2024 |
| Simjol Ventures Limited | Professional & scientific | 2024 |
| Simple Brands Ltd | Wholesale & retail | 2019 |
| Simplify Solution PVT Ltd | Information & communication | 2016 |
| Simply Selfish Limited | Information & communication | 2012 |
| Singlesaint Ltd | Professional & scientific | 2013 |
| Sip&Gather Ltd | Hospitality | 2025 |
| Sitaru Flooring Solutions Ltd | Construction | 2011 |
| Sitelogic Landscape Consultancy Limited | Professional & scientific | 2026 |
| Sithabile Housing and Services Ltd | Health & social care | 2023 |
| SIX Senses Bourne END Ltd | Households | 2026 |
| SJ Press Property Services Ltd | Real estate | 2023 |
| Skepsys Limited | Administrative & support | 2008 |
| Skill 7 Limited | Arts & recreation | 2004 |
| SKR Management Limited | Real estate | 2021 |
| Skts Properties Ltd | Real estate | 2018 |
| Sky Print and Enterprise Ltd | Manufacturing | 2024 |
| Skycroft Limited | Professional & scientific | 2025 |
| Sleapshyde Farm Management Co Ltd | Real estate | 2024 |
| Smart Champs Tuition Ltd | Education | 2021 |
| Smart Price Hunter Ltd | Information & communication | 2015 |
| Smash and Wings Ltd | Hospitality | 2022 |
| Smile Atelier Limited | Information & communication | 2025 |
| Smoothbalance Ltd | Information & communication | 2016 |
| Smudge Creative Ltd | Professional & scientific | 2019 |
| Snap Productions (UK) Ltd | Professional & scientific | 2000 |
| SNK1 Ltd | Real estate | 2019 |
| SNV Consultants Ltd | Professional & scientific | 2017 |
| SO Capital Investments Limited | Real estate | 2021 |
| Soar High Limited | Real estate | 2021 |
| Social Central Ltd | Information & communication | 2018 |
| Social Punch Ltd | Professional & scientific | 2017 |
| Social Work Focus Limited | Administrative & support | 2003 |
| Soda Services Ltd | Professional & scientific | 2023 |
| Sogucak Ltd | Hospitality | 2019 |
| Soho London Events Ltd | Other services | 2023 |
| Solar Plus Technology Ltd | Energy | 2025 |
| Soliea and Beaux Home Decor Ltd | Wholesale & retail | 2025 |
| Solvak Engineers Limited | Mining & quarrying | 2001 |
| Soma Dental Practice Ltd | Health & social care | 2022 |
| Somerston & Co Limited | Administrative & support | 2020 |
| Sorte Digital Solutions Ltd | Wholesale & retail | 2025 |
| Soul Seoul SEO Ltd | Hospitality | 2026 |
| South West Wales Imaging & Diagnostics Limited | Health & social care | 2018 |
| Southcott Pubs Limited | Hospitality | 2024 |
| Spaceman Travel Ltd | Administrative & support | 2015 |
| Spalter Properties Limited | Households | 2024 |
| Spanner & Ratchet Management Services Ltd | Real estate | 2024 |
| Specialist Fabrication and Manufacturing Limited | Construction | 2015 |
| Specialist Spray Coatings Ltd | Construction | 2016 |
| Spectra Property Services Limited | Real estate | 2017 |
| Spice and SIP Limited | Hospitality | 2024 |
| Spirit Beauty Limited | Other services | 2024 |
| Splendid Commodity Limited | Wholesale & retail | 2021 |
| Spma Prop Ltd | Real estate | 2023 |
| Sportsonomy Limited | Arts & recreation | 2010 |
| Sprayed Hertfordshire Ltd | Wholesale & retail | 2024 |
| SPT Energy (UK) Ltd | Energy | 2025 |
| Squires Lane RTM Company Ltd | Households | 2016 |
| SR Peri Peri Ltd | Hospitality | 2023 |
| Ssnp Consulting Limited | Administrative & support | 2024 |
| Ssss Investments 1 Ltd | Real estate | 2011 |
| ST Brother Ltd | Hospitality | 2021 |
| ST Ephraim Ltd | Education | 2022 |
| ST James Restaurant (Bushey) Limited | Hospitality | 1997 |
| ST. Margaret's School Bushey | Education | 1996 |
| St.Clements Property Company Limited | Extraterritorial | 1960 |
| Stafford Street Management Company Limited | Real estate | 2000 |
| Stanco Services Limited | Hospitality | 1992 |
| Stantons Plumbing & Heating Services Limited | Construction | 2018 |
| Star Members Club Ltd | Hospitality | 2025 |
| Startling Trading Limited | Wholesale & retail | 2024 |
| Steadystep Physio Ltd | Health & social care | 2026 |
| Steelworth Developments Limited | Professional & scientific | 1981 |
| Steelworth Limited | Professional & scientific | 1978 |
| Stephendale Property Company Limited | Extraterritorial | 1960 |
| Sterling Capital Developments Limited | Real estate | 2019 |
| Sterling Capital Management Limited | Real estate | 2018 |
| Sterling M & a Ltd | Professional & scientific | 2025 |
| Stewart & Partners Limited | Professional & scientific | 2022 |
| STG Delivery Limited | Transport & logistics | 2025 |
| Sticky Marketing Club Ltd | Real estate | 2005 |
| Stkt Ltd | Other services | 2024 |