| Sarah Kate Curry Design Ltd | Professional & scientific | 2026 |
| Sarah Woodhouse Limited | Health & social care | 2022 |
| Sarga Health Care Ltd | Administrative & support | 2025 |
| Saxon Contractors Limited | Construction | 1996 |
| SB Sports Coaching Ltd | Education | 2015 |
| Scarabee Ltd | Wholesale & retail | 2020 |
| SCG Commercial Limited | Construction | 2019 |
| School Travel Service (STS) Ltd | Administrative & support | 2015 |
| Schools Abroad Limited | Administrative & support | 2014 |
| SCI Specialist Infrastructure Ltd | Information & communication | 2015 |
| Scotts (2023) Limited | Wholesale & retail | 2017 |
| SDR Consulting Ltd | Professional & scientific | 2025 |
| Sealion Films Limited | Information & communication | 2015 |
| Section 24 Drainage Limited | Water & waste | 2011 |
| Sectorfusion Aviation Consulting Ltd | Transport & logistics | 2025 |
| Secure Access Services Limited | Administrative & support | 2002 |
| Seelan & Co Ltd | Wholesale & retail | 2024 |
| Seeview Windows Ltd | Construction | 2002 |
| Seker Holdings Limited | Information & communication | 1995 |
| Seker Tech Limited | Information & communication | 2019 |
| Select Chalets & Hotels Limited | Administrative & support | 1997 |
| Select Overseas Chalets Ltd | Hospitality | 2009 |
| Select School Tours Limited | Administrative & support | 2025 |
| Select School Travel Limited | Administrative & support | 2015 |
| Select Travel (Transport) Limited | Administrative & support | 2015 |
| Semley Lodge Hassocks Limited | Households | 2014 |
| Send Trade Education Provision Ltd | Education | 2025 |
| Sensible Answers Ltd | Professional & scientific | 2014 |
| Sentinel EMS Ltd | Professional & scientific | 2025 |
| Senturion Pharma Ltd | Professional & scientific | 2014 |
| SEP Business Services Ltd | Administrative & support | 2017 |
| Sereno Limited | Information & communication | 2002 |
| Seven Evelyn Terrace Limited | Households | 2003 |
| Sevenoaks Wealth & Investment Management LLP | | 2025 |
| Seventeen Station Road Limited | Real estate | 2019 |
| SH4L Holdings Ltd | Financial services | 2025 |
| Shdy Limited | Wholesale & retail | 2023 |
| Sheard Consulting Services Limited | Professional & scientific | 2022 |
| Shire Place (Crawley) Management Company Limited | Households | 1996 |
| Shojon Lekha (BD) Ltd | Real estate | 2024 |
| Shop Zavio Ltd | Wholesale & retail | 2023 |
| Siblings Property Ltd | Real estate | 2026 |
| Sibs Construction Ltd | Construction | 2025 |
| Sidney West Centre Charity | Arts & recreation | 2009 |
| Sigma Payroll Bureau Ltd | Professional & scientific | 2007 |
| Signal Business Services Limited | Real estate | 2016 |
| Signalbox Micropub Ltd | Hospitality | 2025 |
| Signposts (Mid-Sussex) Ltd | Health & social care | 2003 |
| Silk Hair Boutique Limited | Other services | 2011 |
| Silk Larose Limited | Manufacturing | 2024 |
| Silverwood Group Ltd | Construction | 2017 |
| Simcoai Ltd | Information & communication | 2026 |
| Simon Patience (New Homes) Ltd | Construction | 1996 |
| Simply D & B Construction Ltd | Construction | 2023 |
| Simply Steadi Limited | Education | 2025 |
| Simpsons of Sussex Electrical Limited | Construction | 2016 |
| Sister LED Care Ltd | Health & social care | 2024 |
| Sixfooteight Ltd | Professional & scientific | 2026 |
| SJ Media Ltd | Professional & scientific | 2022 |
| SJ Roofing Contractors Ltd | Construction | 2020 |
| SJL Analysts Limited | Professional & scientific | 2011 |
| Skillstrike Ltd | Wholesale & retail | 2024 |
| Skmk Family Limited | Financial services | 2018 |
| Sky Paragliding Limited | Arts & recreation | 2017 |
| Sleipnir Ltd | Agriculture & fishing | 2026 |
| SM Mobile Mechanics Group Ltd | Wholesale & retail | 2024 |
| SM Seth Limited | Professional & scientific | 2025 |
| Smart Loft Spaces Limited | Construction | 2024 |
| Smart Paint Repairs Limited | Wholesale & retail | 2008 |
| SMART4SOLAR Ltd | Wholesale & retail | 2022 |
| Smartfoam Ltd | Construction | 2018 |
| Smith Taxi Haywards Heath Ltd | Professional & scientific | 2024 |
| Smoke and Smash Limited | Hospitality | 2025 |
| Snap Roll Ltd | Information & communication | 2026 |
| Social, Environmental & Economic Solutions (Soenecs) Limited | Water & waste | 2014 |
| Socks Star Ltd | Wholesale & retail | 2021 |
| Software Surf Ltd | Information & communication | 2019 |
| Sohyped Productions Ltd | Information & communication | 2022 |
| Solar and Energy Gain CIC | Construction | 2025 |
| Solutions 7 Ltd | Information & communication | 2024 |
| Solutions Therapy Sussex Ltd | Health & social care | 2021 |
| Somery Ltd | Professional & scientific | 2025 |
| Sonetto Classics Limited | Information & communication | 2015 |
| South Coast CPD Ltd | Education | 2025 |
| South Coast Veterinary Imaging Ltd | Professional & scientific | 2025 |
| South Downs House Limited | Hospitality | 2021 |
| South Downs View Ltd. | Administrative & support | 2011 |
| South East Aviation and Marine Services Ltd | Other services | 2021 |
| South Eastern Baptist Association | Other services | 2001 |
| Southdown Feeds Limited | Wholesale & retail | 1980 |
| Southern EDM Limited | Professional & scientific | 2016 |
| Southern Medical Services (2008) Limited | Health & social care | 2008 |
| Southern Metal Supplies Limited | Manufacturing | 2010 |
| Southern Steel Services (UK) Limited | Manufacturing | 1997 |
| Southover Manor House (Lewes) Limited | Households | 1996 |
| Southway Developments Limited | Real estate | 2003 |
| Southway Developments London Limited | Construction | 2024 |
| Spa Invest Limited | Financial services | 2019 |
| Spa.Rkle Beauty Salon Limited | Other services | 2012 |
| Spark 3D Limited | Manufacturing | 2022 |