| SEVENTY7 Ventures Ltd | Professional & scientific | 2021 |
| Seymour Management Co. Limited | Households | 1991 |
| SF Lighting Ltd | Administrative & support | 2015 |
| SF Navigation Ltd. | Arts & recreation | 2016 |
| SGM Artist Ltd | Information & communication | 2024 |
| Sgnl London Limited | Manufacturing | 2022 |
| Sguk Properties Ltd | Real estate | 2020 |
| Shades of Light Limited | Construction | 2009 |
| Shah Management Ltd | Real estate | 2025 |
| Shair Ltd | Other services | 2020 |
| Shale OIL & GAS Development Services Ltd | Professional & scientific | 2014 |
| Shanghai Consultants Ltd | Professional & scientific | 2023 |
| Shardeloes House Limited | Real estate | 1970 |
| Sharmi's Kitchen Limited | Hospitality | 2019 |
| Sheehy Bros Ltd | Households | 2023 |
| Shell Egham Hand Car Wash Ltd | Administrative & support | 2021 |
| Shepherd Product Consulting Ltd | Professional & scientific | 2025 |
| Shepherds HUT Investments Limited | Real estate | 2017 |
| Sheridan Court (High Wycombe) Management Company Limited | Households | 2014 |
| Sherline Property Ltd | Real estate | 2025 |
| Sherlock Homez Ltd | Real estate | 2018 |
| Sherwood Collection LLP | | 2023 |
| Shinemark UK Limited | Manufacturing | 2022 |
| Shiny News Food & Wines Ltd | Wholesale & retail | 2021 |
| Shiplake Safehaven Ltd | Real estate | 2025 |
| Shirley Mitchell FGA DGA Limited | Administrative & support | 2012 |
| Shirokuma Ltd | Professional & scientific | 2022 |
| SHL Hartley Wintney Management Company Limited | Households | 2022 |
| Shop Prime Ltd | Wholesale & retail | 2025 |
| Shopenhangers Road Residents Management Company Limited | Households | 2010 |
| Shoshin Ventures Limited | Financial services | 2024 |
| Shoutify Limited | Professional & scientific | 2024 |
| Show Brunch Ltd | Other services | 2024 |
| Show Works Limited | Administrative & support | 2018 |
| Shree Software Solutions Limited | Information & communication | 2021 |
| Shreevah Ltd | Real estate | 2021 |
| Shrisha Enterprise Ltd | Hospitality | 2024 |
| Sidarna Ltd | Administrative & support | 2018 |
| Sidhu K S Limited | Other services | 2018 |
| Sidwid Limited | Arts & recreation | 2024 |
| Siesta Bistro Ltd | Hospitality | 2026 |
| Sigma Medical Ltd | Health & social care | 2025 |
| Signaffairs Ltd | Professional & scientific | 2025 |
| Silver FOX LAB Ltd | Information & communication | 2021 |
| Silverlight Consultancy Ltd | Information & communication | 2022 |
| Silverow Tech Ltd | Information & communication | 2012 |
| Simon Rhodes Ltd | Administrative & support | 2019 |
| Simpar IT Consulting Ltd | Information & communication | 2012 |
| Simpli Chilli Ltd | Other services | 2017 |
| Simplify Change Ltd | Information & communication | 2019 |
| Simply Cleane Ltd | Administrative & support | 2026 |
| Sinai Strategic Limited | Professional & scientific | 2023 |
| Sinpio Ltd | Professional & scientific | 2026 |
| SIP SIP Hurray Ltd | Hospitality | 2024 |
| Sister International Ltd | Wholesale & retail | 2020 |
| Site and Sound Services Limited | Administrative & support | 2008 |
| SIX Claremont Road Limited | Households | 1989 |
| SIX Continents Holdings Limited | Professional & scientific | 1996 |
| SIX Continents Hotels International Limited | Professional & scientific | 1962 |
| SIX Continents Investments Limited | Administrative & support | 1961 |
| SIX Continents Limited | Administrative & support | 1967 |
| SIX Continents Overseas Holdings Limited | Administrative & support | 1991 |
| Siya Property Investments Ltd | Real estate | 2024 |
| SJ Security Solutions Ltd | Administrative & support | 2026 |
| SJ-3 Limited | Extraterritorial | 2005 |
| SJR Capital Ltd | Financial services | 2026 |
| SJR Plumbing + Heating Limited | Construction | 2012 |
| SJS Process Services Limited | Professional & scientific | 2012 |
| Sketch Studios Limited | Wholesale & retail | 2006 |
| Skin & Sculpt Ltd | Other services | 2026 |
| Skip for Hire Ltd | Water & waste | 2019 |
| SKK Solutions Ltd | Wholesale & retail | 2023 |
| SKL Holdings Limited | Real estate | 2025 |
| Sky Blue Consulting Limited | Professional & scientific | 2023 |
| Sky Clinic London Ltd | Health & social care | 2023 |
| Sky Medical Products Ltd | Wholesale & retail | 2023 |
| Sky Roofing Services Ltd | Construction | 2024 |
| Skycladdingroofers Ltd | Construction | 2025 |
| Skyes the Limit Properties Ltd | Real estate | 2023 |
| Skyrox Limited | Transport & logistics | 2023 |
| SL Fire & Electrical Services Limited | Construction | 2012 |
| SL4 Performance LLP | | 2022 |
| SL41RB Ltd | Construction | 2023 |
| Sladeswood (Sonning Common) Management Company Limited | Households | 2020 |
| Slam Dunk Marketing Group Limited | Professional & scientific | 2023 |
| Sliderule One Ltd | Real estate | 2025 |
| Slocov Limited | Other services | 2012 |
| SM Innovateuk Ltd | Information & communication | 2018 |
| Small Build Company Ltd | Construction | 2020 |
| Smart Build DZ Ltd | Construction | 2021 |
| Smart Corpo Ltd | Water & waste | 2020 |
| Smart Touch Football Ltd | Arts & recreation | 2025 |
| Smartcall Technologies Limited | Information & communication | 1994 |
| Smash & Grab Films Ltd | Information & communication | 2013 |
| Smashies Ltd | Hospitality | 2024 |
| SMB Heating & Plumbing Ltd | Construction | 2026 |
| Smiths Lane Management Co. Limited | Households | 1976 |
| Smizco Limited | Other services | 2026 |
| Smogit Ltd | Administrative & support | 2020 |
| Smyth Construction Services Ltd | Construction | 2020 |