| Sanders Design Services Limited | Professional & scientific | 2003 |
| Sanderson Bond Limited | Administrative & support | 2009 |
| Sandford Cottages Limited | Real estate | 1995 |
| Sandgroper Construction Consultants Ltd | Information & communication | 2023 |
| Sandhu Family Holdings Limited | Real estate | 2022 |
| Sandom Property Lettings Ltd | Real estate | 2025 |
| Sandown Road Management Company Limited | Households | 1993 |
| Sandwinn Management Limited | Households | 1973 |
| Sandy Craig Ltd | Households | 2020 |
| Saneka Photo Studio Ltd | Professional & scientific | 2023 |
| Sangha Healthcare Limited | Wholesale & retail | 2017 |
| Sangmatron Ltd | Professional & scientific | 2020 |
| Sania Braids Ltd | Education | 2025 |
| Sanjha Restaurant & Takeaway Limited | Hospitality | 2014 |
| Sanjha Southampton Limited | Professional & scientific | 2017 |
| Sanpau Creative Wellbeing CIC | Education | 2023 |
| Sanpet Ltd | Professional & scientific | 2023 |
| Sansui Ltd | Hospitality | 2013 |
| Santsecure Limited | Administrative & support | 2025 |
| Saplings Childrens Day Nursery Ltd | Education | 2010 |
| Sapphire Fleet Ltd | Transport & logistics | 2024 |
| Sapphire Homes (Southampton) Limited | Real estate | 2017 |
| SAR Support Services Limited | Administrative & support | 2013 |
| Sara Desta Limited | Real estate | 2026 |
| Saraa International Limited | Administrative & support | 2022 |
| Sarah Bolton Travel Ltd | Administrative & support | 2025 |
| Sarah Gray Transport Ltd | Transport & logistics | 2019 |
| Sarah Hindmarsh Design Limited | Professional & scientific | 2003 |
| Sarah Quinn Limited | Other services | 2008 |
| Sarah Quirk Associates Limited | Financial services | 2011 |
| Sarasa Electronics Limited | Information & communication | 1979 |
| Saraswati Asopa Ltd | Other services | 2011 |
| Saray Services Ltd | Transport & logistics | 2024 |
| Sargo Boats UK Limited | Wholesale & retail | 2015 |
| Sarisbury Building Limited | Real estate | 1960 |
| Sarisbury Green C a Services Limited | Hospitality | 1988 |
| Sarisbury Investments Limited | Real estate | 2013 |
| Sarisbury LLP | | 2012 |
| Sark Health Limited | Health & social care | 2023 |
| Sarm SAO Sisters Ltd | Hospitality | 2025 |
| Sarma Consulting Limited | Information & communication | 2008 |
| Sarmak Ltd | Wholesale & retail | 2025 |
| Sarnia Yachts Services (UK) Limited | Administrative & support | 2019 |
| Sartorial Spirits Limited | Manufacturing | 2015 |
| Sarumbear Limited | Information & communication | 2018 |
| SAS Courier Services Ltd | Transport & logistics | 2025 |
| SAS Taxi Rental Ltd | Administrative & support | 2026 |
| Sasi Management Ltd | Hospitality | 2019 |
| Sasuche Ltd | Construction | 2022 |
| Satchel Properties Ltd | Real estate | 2022 |
| Satchell Lane Management Company Limited | Real estate | 2007 |
| Satellite Property Limited | Real estate | 2020 |
| Sathyanath Consulting Ltd | Health & social care | 2011 |
| Satori Healthcare Limited | Health & social care | 2011 |
| Saturn Close 1967 Limited | Extraterritorial | 2014 |
| Satutech Limited | Information & communication | 2025 |
| Saucy Bite Limited | Hospitality | 2026 |
| Saund Asset Management Ltd | Real estate | 2024 |
| Saund Real Estate Ltd | Real estate | 2020 |
| Saund Real Estate SPV 001 Ltd | Real estate | 2025 |
| Saunders Architects LLP | | 2004 |
| Saunders Morgan-Harris Limited | Professional & scientific | 2005 |
| Saunders' Motor Works Limited | Manufacturing | 1945 |
| Saur Technology Services Ltd | Information & communication | 2013 |
| Sauve Solutions Limited | Information & communication | 2009 |
| Savants Restructuring Limited | Professional & scientific | 2018 |
| Savers Wholesale Ltd | Wholesale & retail | 2016 |
| Savinstallations Ltd | Construction | 2022 |
| Savira Construction Ltd | Professional & scientific | 2026 |
| Savouring Roots Ltd | Wholesale & retail | 2026 |
| Savvy Automation Ltd | Manufacturing | 2023 |
| SAW Corporation Ltd | Administrative & support | 2023 |
| Sawbud Ltd | Construction | 2025 |
| Saxon Court (Horton Heath) Limited | Households | 2005 |
| Saxon Gate Management Limited | Households | 1981 |
| Saxon Machinery Limited | Wholesale & retail | 2012 |
| Saxonpr Limited | Construction | 2025 |
| Saxton Scaffolding Limited | Construction | 2017 |
| SAY Scaffolding (Northern) Limited | Construction | 2015 |
| Sayco Sales Ltd | Administrative & support | 2024 |
| Saye HH Ltd | Information & communication | 2025 |
| SB Electrical & Building Maintenance Ltd | Construction | 2022 |
| SB Power Solutions Ltd | Administrative & support | 2023 |
| SB Surfacing Ltd | Construction | 2008 |
| SB Tools Limited | Construction | 2019 |
| Sb.Inc Limited | Professional & scientific | 2023 |
| SBA Property Developments Limited | Real estate | 2022 |
| SBA Property Group Limited | Real estate | 2025 |
| SBA Property Investments Limited | Real estate | 2023 |
| Sbdp LLP | | 2016 |
| SBE Group Holdings Limited | Financial services | 2022 |
| SBK Investments Limited | Other services | 2001 |
| SBK Property Consultants Limited | Real estate | 1987 |
| SBM Research Limited | Wholesale & retail | 2025 |
| SBM Smart Accounting Limited | Professional & scientific | 2017 |
| SBN Estates Ltd | Real estate | 2021 |
| Sboe Limited | Health & social care | 2019 |
| SBS Building and Decorating Services Ltd | Construction | 2025 |
| SBS Event Productions Limited | Administrative & support | 2020 |
| SBS Events Limited | Extraterritorial | 2026 |