| Springbank Management Services Limited | Administrative & support | 2007 |
| Springfield Estate (Oxon) Limited | Real estate | 2017 |
| Springfield Land Profits Ltd | Real estate | 2024 |
| Springvale Rise Management Limited | Households | 2020 |
| Spsre I LLP | | 2024 |
| Spss Limited | Information & communication | 1978 |
| Spvd Ltd | Information & communication | 2022 |
| Squared Engineering Ltd | Professional & scientific | 2021 |
| Squeaky Clean Homes Limited | Households | 2014 |
| Srmdynamics Limited | Wholesale & retail | 2017 |
| SRS Productions Live Ltd | Arts & recreation | 2020 |
| SS Virtual Assistant Ltd | Administrative & support | 2023 |
| SSR Global Solutions Ltd | Transport & logistics | 2025 |
| ST Clement Property Consultancy Limited | Information & communication | 2015 |
| ST Clement Street Management Company Limited | Real estate | 2004 |
| ST Cross Kitchens of Winchester Ltd | Manufacturing | 2018 |
| ST Cross Legals Limited | Professional & scientific | 2020 |
| ST Cross Norman Ltd | Real estate | 2025 |
| ST Kilda Management Company Limited | Other services | 2008 |
| ST Michaels House Freehold Limited | Households | 2024 |
| ST Pancras Court Freehold Limited | Households | 2016 |
| ST Steel Clad Limited | Administrative & support | 1999 |
| ST Swithuns Court Management Company Limited | Real estate | 2013 |
| ST Thomas (Winchester) Management Company Limited | Households | 2020 |
| ST Thomas' Mead Management Company Limited | Households | 2022 |
| ST. David's Technical Services Limited | Information & communication | 2013 |
| ST. Giles Hill Roads Company Ltd | Other services | 2005 |
| ST. James Motor Company Limited | Professional & scientific | 1999 |
| ST. John's Winchester | Hospitality | 2017 |
| ST. Swithun's School Letting Co. Limited | Real estate | 1985 |
| St.Ann's Gate Architects Ltd | Professional & scientific | 2021 |
| St.Denys Property Investments Limited | Real estate | 1963 |
| St.Michaels Development Company Limited | Real estate | 1960 |
| St.Pancras Court Management Limited | Households | 1971 |
| St.Swithuns School(Winchester) | Education | 1910 |
| Stable Close Limited | Professional & scientific | 2011 |
| Stable Spaces Limited | Wholesale & retail | 2021 |
| Stacey Group Ltd | Administrative & support | 2022 |
| Staerk London Ltd | Wholesale & retail | 2024 |
| Stagefreight Limited | Transport & logistics | 1998 |
| Stagetruck Limited | Transport & logistics | 1980 |
| Stainless Steel Centre Limited | Wholesale & retail | 1990 |
| Stamus Risk Management Limited | Administrative & support | 2017 |
| Stand to Electrical Limited | Construction | 2023 |
| Standard Digital Productions Limited | Arts & recreation | 2022 |
| Standen Investments Limited | Professional & scientific | 2016 |
| Stanleys Walk | Real estate | 2003 |
| Star HAT Solutions Limited | Information & communication | 2011 |
| Starburst Software Limited | Information & communication | 1998 |
| Stardust Maritime Limited | Administrative & support | 2024 |
| Starkid Holding Limited | Information & communication | 2021 |
| Starlet Health Care Ltd | Health & social care | 2015 |
| Start UP Gurus Limited | Professional & scientific | 2019 |
| Statler Studio Limited | Information & communication | 2026 |
| Steady Course Ltd | Education | 2005 |
| Steady State Studio Limited | Information & communication | 2017 |
| Steam Marine Ltd | Manufacturing | 2019 |
| Steddles Management Limited | Real estate | 2022 |
| Steeds Consultancy Limited | Professional & scientific | 2025 |
| Steel Erection Services Ltd | Construction | 2012 |
| Steel Hixon Limited | Other services | 1999 |
| Steele & Co Moving Services Limited | Transport & logistics | 2003 |
| Steele Management Limited | Professional & scientific | 2009 |
| Steele Safety Limited | Professional & scientific | 1995 |
| Steep Salvage Limited | Wholesale & retail | 2026 |
| Stella Maris Coaching Limited | Professional & scientific | 2019 |
| Stelling Modular Limited | Manufacturing | 2018 |
| Stelling Properties (Holdings) Limited | Financial services | 2017 |
| Stelling Properties Asset Management Limited | Construction | 2024 |
| Stelling Properties Development Management Limited | Construction | 2024 |
| Stelling Properties JV Member 1 Limited | Construction | 2024 |
| Stelling Properties Limited | Real estate | 2009 |
| Stem and Green Flower Farm Ltd | Agriculture & fishing | 2022 |
| Step One Limited | Professional & scientific | 1999 |
| Stephanie West Limited | Health & social care | 2012 |
| Steps Easton Limited | Professional & scientific | 2020 |
| Stepzen Ltd | Administrative & support | 2021 |
| Sterling Commerce (UK) Limited | Information & communication | 1996 |
| Sterling Pro Limited | Administrative & support | 2009 |
| Steve Head Limited | Professional & scientific | 2005 |
| Steve LEE Ministries Ltd | Administrative & support | 2002 |
| Steven BEE Consulting Limited | Professional & scientific | 2010 |
| Stevens Business Systems Limited | Manufacturing | 2002 |
| STG Associates Ltd | Professional & scientific | 2021 |
| STICKEREDUP4LEMANS Limited | Manufacturing | 2016 |
| Stickleback Games Limited | Information & communication | 2013 |
| Stitch-A-Logo Limited | Manufacturing | 2007 |
| Stock Market Films Limited | Information & communication | 2013 |
| Stockbridge Fishery Association Limited | Arts & recreation | 1911 |
| Stockbridge Hammond Ltd. | Professional & scientific | 2024 |
| Stockbridge Search Limited | Professional & scientific | 2010 |
| Stockholm Court (Winchester) Limited | Real estate | 1983 |
| Stocklund House Management Limited | Households | 2012 |
| Stoic Success Ltd | Professional & scientific | 2025 |
| Stokes & Co. Rural Property Services Ltd | Real estate | 2019 |
| Stolle Surveys Limited | Professional & scientific | 2014 |
| Stondon Investments Limited | Professional & scientific | 2024 |
| Stone Accountancy Services Limited | Professional & scientific | 2010 |
| Stonecastle Developments Limited | Construction | 2021 |
| Stonemasons' Court Management Company Limited | Other services | 1991 |