| Steve Leech Associates Limited | Professional & scientific | 2002 |
| Steve Parish Brickworks Limited | Construction | 2015 |
| Steven Bishop Limited | Construction | 2013 |
| Stevenson Property Management Limited | Real estate | 2016 |
| Stewart's Decorators Limited | Construction | 2003 |
| Stewarts Road Management Company Limited | Administrative & support | 1988 |
| STI Comms Ltd | Wholesale & retail | 2020 |
| Sticks Ltd | Construction | 1996 |
| Stigglee Group Ltd | Wholesale & retail | 2020 |
| Stingray Rights Management Limited | Information & communication | 2007 |
| STM Care Limited | Health & social care | 2022 |
| Stoic Finance Limited | Administrative & support | 2023 |
| Stone Costruct Limited | Construction | 2017 |
| Stonunwa Limited | Health & social care | 2025 |
| Storelock Ltd | Other services | 2015 |
| Stourport Marina Limited | Real estate | 1979 |
| Strand Glassfibre Limited | Extraterritorial | 1994 |
| Strange Holdings Group Ltd | Financial services | 2023 |
| Strange&Bird Ltd | Construction | 2023 |
| Stratofleet Ltd | Manufacturing | 2025 |
| Stream Light Solutions Ltd | Administrative & support | 2017 |
| Streamercentral Ltd | Information & communication | 2025 |
| Street Energy (Holdings) Limited | Construction | 2013 |
| Street Energy Limited | Professional & scientific | 2009 |
| Street Energy Surveys Limited | Construction | 2002 |
| Street Home Solutions Ltd | Administrative & support | 2015 |
| Street Shawarma Ltd | Hospitality | 2025 |
| Strelet Construction Ltd | Construction | 2020 |
| Stretch-Wide Ltd | Education | 2025 |
| Stric Lands Limited | Agriculture & fishing | 2012 |
| Strong Lines Physiotherapy Limited | Health & social care | 2015 |
| Structura Homes Limited | Construction | 2020 |
| Stryders Ltd | Hospitality | 2019 |
| Stuchar Limited | Real estate | 2023 |
| Studio Music Company Limited | Information & communication | 2007 |
| Studiocare Professional Audio Limited | Other services | 1998 |
| Stunning Drive Ltd | Transport & logistics | 2019 |
| STV Machinery Limited | Administrative & support | 2017 |
| Sudborough Country Cottages Limited | Real estate | 2025 |
| Sufficient Grace Ltd | Health & social care | 2014 |
| Sugar Coated Beauty Limited | Wholesale & retail | 2019 |
| Sugarpoke Ltd | Wholesale & retail | 2009 |
| Sugary Swirls Ltd | Wholesale & retail | 2024 |
| Suhana Enterprise Ltd | Hospitality | 2018 |
| Sukhi Autos Ltd | Wholesale & retail | 2025 |
| Sully's Bakehouse Ltd | Wholesale & retail | 2026 |
| Summit Development Ltd | Real estate | 2003 |
| Summit Edge Property Limited | Real estate | 2025 |
| Summit Recruiters Limited | Administrative & support | 2023 |
| Summitshoptcg Limited | Wholesale & retail | 2025 |
| Sunrise Sanctuary Healthcare Limited | Construction | 2019 |
| Sunset Media Holdings Ltd | Arts & recreation | 2016 |
| Sunsetgate Ltd | Other services | 2017 |
| Superior Cars Limited | Wholesale & retail | 2008 |
| Supernova LED Lighting Limited | Wholesale & retail | 2010 |
| Support Factory Ltd | Administrative & support | 2025 |
| Support Integrity Services Ltd | Education | 2020 |
| Support Northamptonshire | Health & social care | 2015 |
| Surefix Building Contractors Limited | Construction | 2024 |
| Surefix Roads Limited | Construction | 2025 |
| Surehaul Solutions Limited | Transport & logistics | 2025 |
| Surer Management Limited | Hospitality | 2021 |
| Suresafe Electrical Services Ltd | Construction | 2020 |
| Sustainable Energy Projects Limited | Professional & scientific | 2009 |
| Sutton Design Ltd | Professional & scientific | 2024 |
| SV Vanik Developments Ltd | Construction | 2026 |
| Swamisooch Ltd | Real estate | 2016 |
| Swanage Seaview Ltd | Real estate | 2026 |
| Swann Comms Limited | Information & communication | 2016 |
| Swannell Comms Ltd | Information & communication | 2016 |
| Swanspool Allotments Ltd | Agriculture & fishing | 2022 |
| Swedish Kitchen Limited | Hospitality | 2019 |
| Swedish Kitchen Rounds Ltd | Hospitality | 2026 |
| Sweet Avenue Ltd | Hospitality | 2024 |
| Sweet Drops of Heaven Ltd | Manufacturing | 2016 |
| Sweet Futures Limited | Education | 2019 |
| Sweet Kendi Limited | Professional & scientific | 2023 |
| Sweet Lounge Group Ltd | Manufacturing | 2019 |
| Sweetbitz Limited | Wholesale & retail | 2010 |
| Swiftertainment Ltd | Other services | 2018 |
| Swimfin Limited | Manufacturing | 2006 |
| Swirl Trading Limited | Construction | 2001 |
| SWR Sales Limited | Wholesale & retail | 2023 |
| Syed Jafri Fabric Care Ltd | Other services | 2017 |
| Syltem Health Care Ltd | Health & social care | 2023 |
| Symetra Holdings Ltd | Real estate | 2025 |
| Synch Services Ltd | Health & social care | 2024 |
| Synomed Limited | Health & social care | 2022 |
| Synthetic Resins Limited | Professional & scientific | 1933 |
| Systemperform Limited | Professional & scientific | 2020 |
| Szabo&Illes Limited | Other services | 2012 |
| T & K Home Improvements Limited | Construction | 1987 |
| T a Grant Limited | Other services | 2021 |
| T H Environmental Limited | Transport & logistics | 2010 |
| T J O'Reilly Limited | Wholesale & retail | 2018 |
| T J Robinson Limited | Professional & scientific | 2016 |
| T L Scott Group Limited | Financial services | 2024 |
| T L Scott Limited | Real estate | 2022 |
| T Transport Group Ltd | Transport & logistics | 2025 |
| T&E Transport Ltd | Transport & logistics | 2026 |