| Shooting Stars Preschool Ltd | Education | 2021 |
| Shoreseeker Ltd | Administrative & support | 2015 |
| Short Lets (Southampton) Ltd | Real estate | 2020 |
| Showsport Publishing Limited | Information & communication | 2003 |
| Shri Krish UK Ltd | Wholesale & retail | 2017 |
| Shukan Food & Wine Ltd | Wholesale & retail | 2023 |
| Silver Sparrow Management Limited | Professional & scientific | 2024 |
| Simia-Entertainment Ltd | Manufacturing | 2020 |
| Singing Gorilla Projects | Health & social care | 2015 |
| Sirius Concepts Media Limited | Professional & scientific | 2012 |
| Sisterly Care Limited | Other services | 2007 |
| Siticommerce Ltd | Wholesale & retail | 2017 |
| SJH Consulting Ltd | Professional & scientific | 2024 |
| Skillzer Ltd | Wholesale & retail | 2025 |
| Skin Vanity Aesthetics Limited | Other services | 2025 |
| SLG Estates Ltd | Real estate | 2022 |
| Smart Property Management (South) Ltd | Households | 2016 |
| SMC Deesand Limited | Wholesale & retail | 2025 |
| Smithe & Co Limited | Professional & scientific | 2023 |
| SMM Productions Limited | Manufacturing | 2020 |
| Smoky's Grill SG Ltd | Hospitality | 2021 |
| Smooth Laser Clinic Limited | Other services | 2021 |
| SMT Management Consultants Ltd | Administrative & support | 2010 |
| Snai Construction Limited | Construction | 2025 |
| Snake Code Limited | Information & communication | 2021 |
| Soaked Automotive Detailing Limited | Wholesale & retail | 2023 |
| Soalda Limited | Financial services | 2022 |
| Sociavara Ltd. | Professional & scientific | 2025 |
| SOI Dog Marketing Ltd | Wholesale & retail | 2021 |
| Solaro Systems Ltd | Construction | 2025 |
| Solent Accounting Limited | Professional & scientific | 2018 |
| Solent Arena Ltd | Arts & recreation | 2025 |
| Solent Automation Ltd | Manufacturing | 2019 |
| Solent Caravan & Motorhome Services Ltd | Wholesale & retail | 2021 |
| Solent Celebrations Ltd | Administrative & support | 2026 |
| Solent Electrical Contractors Limited | Construction | 2018 |
| Solent Expert Ltd | Professional & scientific | 2022 |
| Solent Harbour Limited | Real estate | 2020 |
| Solent Ideas Ltd | Administrative & support | 2020 |
| Solent Innovation Ltd | Professional & scientific | 2022 |
| Solent Insulation Services Limited | Other services | 1988 |
| Solent Motor Services Limited | Wholesale & retail | 2007 |
| Solent Remade CIC | Professional & scientific | 2021 |
| Solent Signature Homes Limited | Construction | 2026 |
| Solmar Limited | Professional & scientific | 2010 |
| South Coast Fitness Academy Ltd | Other services | 2025 |
| South Downs Limited | Water & waste | 2001 |
| South Downs Outdoor Ltd | Arts & recreation | 2012 |
| Southdowns Plumbing Co. Limited | Construction | 2025 |
| Southern Energy Training Academy Ltd | Education | 2015 |
| Southern Joinery Supplies Ltd | Manufacturing | 2023 |
| Southern Lease Ltd | Real estate | 2025 |
| Southern Motor Contracts Holdings 2 Limited | Financial services | 2020 |
| Southern Motor Contracts Holdings Limited | Professional & scientific | 2006 |
| Southern Motor Contracts Limited | Administrative & support | 1988 |
| Southern Rest Limited | Real estate | 2025 |
| Southern Steps UK Ltd | Arts & recreation | 2026 |
| Southforge Holdings Ltd | Financial services | 2026 |
| Southforge Industrial Ltd | Wholesale & retail | 2022 |
| Sparkle Accounting Ltd | Professional & scientific | 2018 |
| Sparkle Services Ltd | Administrative & support | 2020 |
| Sparks Accounting Ltd | Professional & scientific | 2016 |
| Sparks Accounting Services Ltd | Professional & scientific | 2020 |
| Sparks Eight Ltd | Administrative & support | 2020 |
| Sparks Five Ltd | Construction | 2020 |
| Sparks Four Ltd | Administrative & support | 2020 |
| Sparks Management Ltd | Professional & scientific | 2026 |
| Sparks Nine Ltd | Administrative & support | 2020 |
| Sparks One Ltd | Administrative & support | 2018 |
| Sparks Payroll Ltd | Financial services | 2020 |
| Sparks SIX Ltd | Administrative & support | 2020 |
| Sparks TEN Ltd | Administrative & support | 2020 |
| Spars Heath Limited | Health & social care | 2025 |
| Speak on Podcasts Ltd | Professional & scientific | 2022 |
| Speedcut Limited | Professional & scientific | 1996 |
| Spinnaker Removals Ltd | Transport & logistics | 2026 |
| Spire Education Services Ltd | Education | 2019 |
| Sports Retail Limited | Wholesale & retail | 2025 |
| SPP Solutions Limited | Education | 2010 |
| Spry Newsagent Limited | Wholesale & retail | 2026 |
| Spudlickers Ltd | Hospitality | 2025 |
| Spurway Holdings Limited | Professional & scientific | 2020 |
| Spurway Scaffold Limited | Construction | 2016 |
| Spurway Scaffolding Limited | Construction | 2020 |
| SRC Electrical Solutions UK Ltd | Construction | 2023 |
| Sreelekha Consultancy PVT Ltd | Information & communication | 2017 |
| Sreelekha Homes Ltd | Real estate | 2026 |
| SRL Engineering (Southern) Ltd | Professional & scientific | 2024 |
| SSG Recruitment Services Ltd | Administrative & support | 2025 |
| ST. Clares PRE School | Education | 2012 |
| Stability Engineering Ltd | Construction | 2025 |
| Stage One Services Crew Limited | Administrative & support | 2009 |
| Stamped With Love Ltd | Manufacturing | 2018 |
| Starjammer Hosting Limited | Information & communication | 2013 |
| Starjammer Limited | Construction | 2015 |
| Start UP Janitor Limited | Professional & scientific | 2017 |
| Stasys Drylining Ltd | Construction | 2021 |
| Stavros Bay Limited | Hospitality | 2019 |
| STC Automotives Ltd | Professional & scientific | 2020 |
| Stenning Software Services Limited | Information & communication | 1985 |