| SSK 11 Limited | Financial services | 2025 |
| ST Albans Carpentry and Joinery Ltd | Construction | 2025 |
| ST Georges European Limited | Transport & logistics | 2011 |
| ST Georges European Removals and Storage Limited | Transport & logistics | 2015 |
| ST Joseph Interiors Ltd | Construction | 2025 |
| Stable Yard Flowers Limited | Wholesale & retail | 2026 |
| Stack & Quill Ltd | Information & communication | 2023 |
| Stadiumheritage Limited | Professional & scientific | 2026 |
| Stafford Court (Bexley) Freehold Limited | Real estate | 2007 |
| Stage Property Developments Ltd | Real estate | 2025 |
| Stanley Lift Works Limited | Professional & scientific | 2024 |
| Stanton Court (Longlands) Limited | Households | 1984 |
| Stanton Electrical Ltd | Construction | 2020 |
| Stanway Little Associates Ltd | Administrative & support | 2008 |
| Star Boilers & Bathrooms Ltd | Construction | 2024 |
| Star Circle Ltd | Real estate | 2022 |
| Star Construction and Cleaning Limited | Construction | 2025 |
| Star Developers Ltd | Real estate | 2020 |
| Star Properties Development Limited | Real estate | 2023 |
| Starcrest Care Group Ltd | Health & social care | 2022 |
| Starlight Grove Ltd | Health & social care | 2026 |
| Stay Home 2020 Limited | Real estate | 2020 |
| Stay Standard Ltd | Professional & scientific | 2025 |
| STC Plumbing and Heating Ltd | Construction | 2013 |
| Stem Maintenance Ltd | Manufacturing | 2023 |
| Stenab Build Limited | Construction | 2017 |
| Stenab Limited | Professional & scientific | 2015 |
| Step Care Services Limited | Real estate | 2024 |
| Stephen Connell Ltd | Hospitality | 2023 |
| Stephen Gough Trading Limited | Real estate | 2001 |
| Stephome Property Services Limited | Real estate | 2026 |
| Stepz Limited | Transport & logistics | 2018 |
| Sterling Bapc Ltd | Financial services | 2009 |
| Sterling Business Consultants Limited | Financial services | 1996 |
| Sterling College (London) Limited | Hospitality | 2009 |
| Sterling Education Services Ltd | Administrative & support | 2023 |
| Stevens Commissioning Limited | Professional & scientific | 2019 |
| Stewart Watson Services Limited | Administrative & support | 2018 |
| Stewarts Electrics Limited | Construction | 2011 |
| Stickbuild Homes Ltd | Professional & scientific | 2019 |
| Stirling Medical & Scientific Ltd | Manufacturing | 2011 |
| Stkh Ltd | Transport & logistics | 2025 |
| STN Capital Ltd. | Administrative & support | 2022 |
| Stockcrowd UK Ltd | Professional & scientific | 2019 |
| Stonecraft London Limited | Extraterritorial | 2016 |
| Stoneford Holdings Limited | Financial services | 2019 |
| Stoneham (Kitchens) Limited | Extraterritorial | 1970 |
| Stoneham Group Limited | Financial services | 2019 |
| Stoneham PLC | Manufacturing | 1936 |
| Stoneham Properties Limited | Financial services | 2019 |
| Stonewolf Properties Limited | Real estate | 2025 |
| Stoney OWL Ltd | Real estate | 2024 |
| Storeyz Limited | Administrative & support | 2015 |
| Storm Business Solutions Limited | Professional & scientific | 2017 |
| Storymine Community Interest Company | Arts & recreation | 2017 |
| Straight UP Dance & Theatre Ltd | Arts & recreation | 2025 |
| Straight Way Ltd | Information & communication | 2021 |
| Strail Engineering Ltd | Construction | 2022 |
| Strano Medical Limited | Other services | 2013 |
| Stratotech Ltd | Information & communication | 2025 |
| Stratton Beechmont Limited | Real estate | 2018 |
| Strauss Surveying Services Limited | Construction | 2018 |
| Strawberry Blonde Films Limited | Information & communication | 2017 |
| Streamline Business Service Ltd. | Professional & scientific | 2003 |
| Streamline Management Limited | Professional & scientific | 1997 |
| Strevens & SON Limited | Transport & logistics | 2024 |
| Stringer Communication Services Ltd. | Transport & logistics | 2001 |
| Stryve Ltd | Professional & scientific | 2025 |
| Studio 11 Beauty and Wellbeing Ltd | Other services | 2017 |
| Studio 11 Hair Design and Wellbeing Ltd | Other services | 2017 |
| Studio Fiftyone Ltd | Professional & scientific | 2020 |
| Studio Marc Design Limited | Professional & scientific | 2008 |
| Studio Nuvo Ltd | Professional & scientific | 2022 |
| Studio RTN Limited | Information & communication | 2023 |
| Sturgess Management Limited | Administrative & support | 2022 |
| Stux Consulting Ltd | Information & communication | 2020 |
| Styled by Sissy Ltd | Arts & recreation | 2019 |
| Sublimitas Limited | Administrative & support | 2018 |
| Subtle Quotes Limited | Wholesale & retail | 2024 |
| Succeed in Languages Ltd | Administrative & support | 2008 |
| Success Tuition Limited | Education | 2022 |
| Success Without Limits Limited | Administrative & support | 2015 |
| Suite Deal Limited | Administrative & support | 2024 |
| Sullivan Professional Services Ltd | Real estate | 2019 |
| Summer Inns Public Houses Limited | Hospitality | 2016 |
| Summerfield Hotel Limited | Administrative & support | 2024 |
| Sumthings Limited | Professional & scientific | 2018 |
| Suncom Consultants Limited | Administrative & support | 2020 |
| Sundridge Holdings Limited | Wholesale & retail | 1984 |
| Sunlife Solar UK Limited | Construction | 2025 |
| Sunny Build Ltd | Construction | 2018 |
| Sunny Delivery Ltd | Transport & logistics | 2023 |
| Sunny Smile Limited | Health & social care | 2010 |
| Sunrays Accounting Limited | Professional & scientific | 2025 |
| Sunstone Developments (Twickenham) Limited | Real estate | 2015 |
| Sunstone Holdings Limited | Administrative & support | 2016 |
| Sunstone Properties Limited | Administrative & support | 2003 |
| Sunstone Refurbishments Limited | Administrative & support | 2013 |
| Sunstone South Limited | Administrative & support | 2016 |
| Super American Hand Car Wash Ltd | Administrative & support | 2021 |