| Sefana Ltd | Health & social care | 2017 |
| Selsey Dental Practice Ltd | Health & social care | 2010 |
| Senior MSL Consulting Ltd | Professional & scientific | 2017 |
| Services 4 Business Limited | Information & communication | 1999 |
| Seven Times Media Ltd | Information & communication | 2025 |
| Seventeen Media Ltd | Professional & scientific | 2017 |
| Severn Consturction Limited | Arts & recreation | 2004 |
| Seyanou Ltd | Real estate | 2021 |
| SG Fintech Ltd | Professional & scientific | 2017 |
| Shahram Moallemi & Co Limited | Professional & scientific | 2005 |
| Shahroozi Enterprises Ltd | Real estate | 2011 |
| Shahroozi Investments Ltd | Real estate | 2011 |
| Shed Research Consulting Limited | Professional & scientific | 2011 |
| Shellfish by the Sea Events Ltd | Hospitality | 2025 |
| Shenyang Regression Ltd | Transport & logistics | 2018 |
| Shep Retail Limited | Extraterritorial | 2018 |
| Shepherd Albourne Limited | Financial services | 2021 |
| Sherrards Employment Services Ltd | Professional & scientific | 2003 |
| Sherrards EOT Ltd | Professional & scientific | 2025 |
| Sherrards Occupational Health Ltd. | Professional & scientific | 2014 |
| Shimwell Limited | Real estate | 2015 |
| Shine Theatre Trust | Education | 2004 |
| Short Circuit Electrical Ltd | Construction | 2016 |
| Shripney Carriage Company Limited | Wholesale & retail | 2012 |
| SI Signore Ltd | Hospitality | 2015 |
| Silver Rocket Brewing Ltd | Manufacturing | 2018 |
| Silverdale East Limited | Extraterritorial | 2005 |
| Simon Hall Agri Ltd | Agriculture & fishing | 2009 |
| Simon Winnard & Company Limited | Professional & scientific | 2009 |
| Simply Bamboo Limited | Wholesale & retail | 2006 |
| Simply Swim Sussex Ltd | Arts & recreation | 2013 |
| Simtraincheck Ltd | Transport & logistics | 2017 |
| Since and Forever Limited | Extraterritorial | 2014 |
| SIO Productions Ltd | Information & communication | 2023 |
| Sjm*Create Ltd | Information & communication | 2018 |
| Skilltran Limited | Construction | 1988 |
| Sky Eagle Sussex Ltd | Wholesale & retail | 2023 |
| Slantec Limited | Professional & scientific | 2012 |
| Slicklord Bookkeeping Ltd | Professional & scientific | 2022 |
| Slicklord Gaming Ltd | Information & communication | 2024 |
| Slicklord Ltd | Professional & scientific | 2021 |
| SM Tech Consultancy Ltd | Information & communication | 2023 |
| Small Opportunities Limited | Health & social care | 2007 |
| Smart Telecom (UK) Limited | Professional & scientific | 2010 |
| Smile Studio Trading Limited | Health & social care | 2006 |
| Smpl Innovations Ltd | Manufacturing | 2014 |
| Smrm Holdings Ltd | Real estate | 2024 |
| SNS Automotive UK Ltd | Wholesale & retail | 2026 |
| Soccer Passport Ltd | Administrative & support | 2024 |
| Social Innovation for ALL C.I.C. | Education | 2022 |
| Softech Health Limited | Health & social care | 2020 |
| Solté Club Ltd | Other services | 2025 |
| Solway and Dulwich Management Ltd | Households | 2021 |
| Somosis IT Solutions Limited | Information & communication | 2004 |
| Soni Manufacturing Limited | Manufacturing | 2025 |
| Sonny Management Company Limited | Households | 1989 |
| Sound Bath Ltd | Professional & scientific | 2026 |
| Soundrop Limited | Other services | 2024 |
| Sourcing Solved Ltd | Administrative & support | 2009 |
| South Coast Automotive Ltd | Wholesale & retail | 2019 |
| South Downs Drone Survey Ltd | Professional & scientific | 2026 |
| South Downs Holidays Ltd | Hospitality | 2025 |
| South Downs Leadership and Management Services Ltd | Information & communication | 2013 |
| Southern Aero Limited | Transport & logistics | 2017 |
| Southern Recovery Service Transport Ltd | Transport & logistics | 2016 |
| Southern Right Offshore Ltd | Professional & scientific | 2024 |
| Southern Stone Installations Ltd | Construction | 2023 |
| Sovereign Radio Limited | Information & communication | 1996 |
| SP Business Limited | Wholesale & retail | 2019 |
| Spearhead Sussex Ltd | Wholesale & retail | 2020 |
| Spencer Road (Sussex) Limited | Construction | 2018 |
| Spicepot Ltd | Administrative & support | 2010 |
| Spicer and Moore Limited | Information & communication | 2008 |
| Spidge Addington Limited | Professional & scientific | 2025 |
| Spine & Brain Ltd | Health & social care | 2018 |
| Spiral Promotions Limited | Wholesale & retail | 2009 |
| Spiritbond Capital Limited | Other services | 2019 |
| Spiritbond Investments LLP | | 2023 |
| Spiritbond Property Services Ltd | Real estate | 2017 |
| Spiritique Foundation | Arts & recreation | 2017 |
| Spirou Sharma LLP | | 2018 |
| Splash FM Limited | Information & communication | 2001 |
| Sports Tech for Life Ltd | Manufacturing | 2020 |
| Spover Ltd | Information & communication | 2025 |
| Square One Maintenance Ltd | Construction | 2023 |
| SRS Land Holdings Ltd | Real estate | 2017 |
| ST Anne's Gardens Residents Association Ltd | Households | 1997 |
| ST James Lettings Ltd | Real estate | 2007 |
| ST Simeon's Church Trust | Health & social care | 2004 |
| Stafford House Apartments Management Company Limited | Households | 2019 |
| Stafford Property Maintenance Ltd | Construction | 2021 |
| Stallion Plant Services Limited | Professional & scientific | 1981 |
| Starley Close Management Limited | Households | 2023 |
| Stars & Soltire Limited | Professional & scientific | 2025 |
| Statement Landscapes Ltd | Administrative & support | 2019 |
| Station Road Carpets (UK) Ltd | Wholesale & retail | 2012 |
| Stay Finder Ltd | Administrative & support | 2025 |
| Steamtdd Limited | Professional & scientific | 2017 |
| Stella Rose Ltd | Real estate | 2022 |
| Steve Fisher Productions Ltd | Arts & recreation | 2013 |