| Sportskool in the Community CIC | Education | 2024 |
| Spot on Screeds Ltd | Construction | 2017 |
| Spotless Standard Limited | Administrative & support | 2026 |
| Spotlight Creations Limited | Hospitality | 2024 |
| Spotlight Property Management Limited | Real estate | 2024 |
| SPP Roofing Ltd | Construction | 2014 |
| Spray and Go Ltd | Administrative & support | 2026 |
| Spray Foam Removal Ltd | Administrative & support | 2020 |
| Spray IT Commercials Limited | Wholesale & retail | 2017 |
| Spray TEK Ltd. | Wholesale & retail | 1998 |
| Sprayfine Limited | Construction | 2009 |
| Sprayit ROB Ltd | Wholesale & retail | 2015 |
| Sprayzone Holdings Limited | Administrative & support | 2016 |
| Sprayzone Limited | Construction | 2000 |
| Spreadbury Roofing Ltd | Construction | 2023 |
| Spring Chiropractic Limited | Health & social care | 2004 |
| Spring Gardens (Hedge END) Limited | Extraterritorial | 2005 |
| Spring Meadows Hampshire Ltd | Administrative & support | 2024 |
| Spring Mount Investments Private Limited | Extraterritorial | 2020 |
| Springboard Education and Care Ltd | Health & social care | 2020 |
| Springer Investments Limited | Real estate | 1998 |
| Springfield Properties (UK) Limited | Real estate | 2000 |
| Springford Financial Solutions Limited | Financial services | 2018 |
| Springing Care Limited | Health & social care | 2023 |
| Springmediamgmt Ltd | Professional & scientific | 2023 |
| Springworks Ltd | Information & communication | 2009 |
| Sprinkles Gelato 2 Limited | Hospitality | 2013 |
| Sprinkles Gelato 3 Limited | Hospitality | 2014 |
| Sprinkles Gelato Franchise Limited | Hospitality | 2013 |
| Sprinkles Gelato Ltd | Hospitality | 2012 |
| Sprites Healthcare Recruitment Limited | Administrative & support | 2016 |
| Sproco Ltd. | Construction | 2017 |
| Spruce Development (South East 2) Limited | Construction | 2018 |
| Spruce Storage Ltd | Transport & logistics | 2017 |
| Spry Europe Limited | Wholesale & retail | 2019 |
| SPT Plumbing & Heating Limited | Construction | 2017 |
| Spudd Mobile Ltd. | Information & communication | 2011 |
| Spurwing Ltd | Construction | 2012 |
| Spyglass Limited | Wholesale & retail | 2017 |
| SQS Security Ltd | Administrative & support | 2026 |
| Squalk Limited | Information & communication | 2019 |
| Square 1 Architectural Solutions Limited | Construction | 2011 |
| Square 1 Balustrades Limited | Construction | 2017 |
| Square 1 Media Limited | Professional & scientific | 2019 |
| Square Rock Limited | Construction | 2025 |
| Squaremouse Ltd | Information & communication | 2017 |
| Squeaky Wheelbarrow Ltd | Hospitality | 2018 |
| SR Accounting Ltd | Professional & scientific | 2019 |
| SR Builders & Glazing Limited | Manufacturing | 2023 |
| SR Glazing Ltd | Construction | 2020 |
| SR Gray Consult Limited | Professional & scientific | 2026 |
| Srbusa LLP | | 2019 |
| SRC Composites Limited | Manufacturing | 2024 |
| SRC Mechanics Ltd | Wholesale & retail | 2023 |
| SRE Properties Ltd | Real estate | 2024 |
| Srealty Ltd | Real estate | 2022 |
| Sreeguru Foods Limited | Hospitality | 2024 |
| SRG Care Services Limited | Health & social care | 2018 |
| SRG Kingston Care Home Limited | Health & social care | 2019 |
| Srgassets Ltd | Financial services | 2025 |
| SRH Engraving Limited | Professional & scientific | 2024 |
| SRI Lakshmi Vinayaka PVT Limited | Wholesale & retail | 2026 |
| Srinidhi Medical Services Limited | Real estate | 2021 |
| Srinivasa Stores Ltd | Wholesale & retail | 2024 |
| SRJ Sales Limited | Wholesale & retail | 2024 |
| Sroda Ltd | Other services | 2015 |
| SRR Marine Ltd | Construction | 2019 |
| SRS (Southern) LLP | | 2018 |
| SS BD Limited | Hospitality | 2026 |
| SS1 Lettings Limited | Real estate | 2022 |
| SS1 Limited | Professional & scientific | 2011 |
| SSB GAS Limited | Construction | 2025 |
| SSG Southampton Ltd | Administrative & support | 2025 |
| SSH Inc Ltd | Real estate | 2023 |
| SSJ Health Limited | Health & social care | 2021 |
| Ssjudge Limited | Real estate | 2018 |
| Ssls Designs Limited | Extraterritorial | 2025 |
| SSM Care Limited | Health & social care | 2013 |
| SSO Visuals Limited | Wholesale & retail | 2023 |
| Ssource Clothing Ltd | Wholesale & retail | 2025 |
| SSP Carpentry and Joinery Ltd | Manufacturing | 2021 |
| SSP Spice Ltd | Wholesale & retail | 2022 |
| Sspw Holdings Limited | Real estate | 2022 |
| SSR Stars Ltd | Wholesale & retail | 2020 |
| SSS Bains Property Ltd | Real estate | 2025 |
| SSU Cognition Advisory Limited | Health & social care | 2025 |
| ST & MT Holdings Limited | Financial services | 2026 |
| ST Anne's Catholic School | Education | 2012 |
| ST Catherines Road Freehold Limited | Real estate | 2011 |
| ST Cross Mede Management Company Limited | Households | 1996 |
| ST Cross Mews Management Ltd | Households | 2007 |
| ST Cuthberts Drive Management Company Limited | Households | 2016 |
| ST Denys Area Community Association | Arts & recreation | 2010 |
| ST Francis Early Years Limited | Education | 2025 |
| ST George Foundation Limited | Health & social care | 2006 |
| ST James Chiropractic Clinic Limited | Health & social care | 2002 |
| ST James Court (Southsea) Ltd | Real estate | 2001 |
| ST James Laundry Ltd | Other services | 2026 |
| ST James Mews Management Limited | Households | 2013 |
| ST James Place (Southampton) Residents Company Limited | Households | 2008 |