| Sebor Associates Limited | Professional & scientific | 2021 |
| Second Life Solar Ltd | Water & waste | 2022 |
| Securenest Management Ltd | Hospitality | 2024 |
| Seductive Ltd | Administrative & support | 2015 |
| Sedulous Rail Ltd | Construction | 2024 |
| Seed Medical Limited | Health & social care | 2026 |
| Seen Ltd | Education | 2012 |
| Sefa Engineering Limited | Manufacturing | 2010 |
| Segnaro Limited | Construction | 2024 |
| Selah Properties Limited | Real estate | 2023 |
| Select Developments Southern Ltd | Construction | 2017 |
| Select Cars Eastbourne Limited | Wholesale & retail | 2006 |
| Self Consultants Limited | Professional & scientific | 2018 |
| Selinon Limited | Administrative & support | 2013 |
| Sellens Business Services Limited | Real estate | 2000 |
| Selmeston House (Eastbourne) RTM Company Limited | Households | 2009 |
| Selwyn House (Eastbourne) Limited | Households | 1963 |
| Senco Support Ltd | Education | 2024 |
| Send a Smile Gifting Limited | Wholesale & retail | 2024 |
| Senko Car Services Limited | Administrative & support | 2022 |
| Senlac Group Travel Ltd | Administrative & support | 2022 |
| Sensorial Skincare Limited | Extraterritorial | 2021 |
| Sensory Retreats Limited | Extraterritorial | 2019 |
| Sensory Sleep Limited | Extraterritorial | 2023 |
| Sensory Treat Box Limited | Extraterritorial | 2021 |
| Sents Technologies Limited | Information & communication | 2021 |
| Separate Doors CIC | Information & communication | 2019 |
| SER Furniture Limited | Wholesale & retail | 2018 |
| SER Group Holdings Limited | Financial services | 2018 |
| SER Logistics Ltd | Transport & logistics | 2017 |
| Serenity With ESE Ltd | Health & social care | 2026 |
| Sereno Care Ltd | Health & social care | 2026 |
| Service to Millions Limited | Professional & scientific | 2017 |
| Setcot Employment Law Limited | Professional & scientific | 2018 |
| Setnova Ltd | Professional & scientific | 2026 |
| Seven Church Lane Ltd | Hospitality | 2026 |
| Seven Cliffs Limited | Real estate | 1958 |
| Seven Haematology Ltd | Health & social care | 2024 |
| Seven Sisters Investments Limited | Real estate | 1996 |
| Seven Sisters Rising Limited | Other services | 2025 |
| Seven Stars Eatery Ltd | Hospitality | 2025 |
| Seven Ways Property Co. Limited | Households | 1969 |
| Sevrona Ltd | Administrative & support | 2017 |
| SEW Sussex | Other services | 2020 |
| Sewell-Jolly Ltd | Health & social care | 2022 |
| Sftb Holdings Limited | Financial services | 2025 |
| SG Construction Southeast Ltd. | Construction | 2016 |
| SG Property Management Ltd | Hospitality | 2025 |
| SGT Building & Civil Contractors Ltd | Extraterritorial | 2024 |
| SGW Investments Limited | Real estate | 2018 |
| SH Property Consultants Ltd | Real estate | 2015 |
| Shades Restaurant (Eastbourne) Limited | Hospitality | 1999 |
| Shah Professional Ltd | Health & social care | 2021 |
| Shahabs Dream Ltd | Real estate | 2024 |
| Shaiyl Investments Limited | Real estate | 2021 |
| Shamanca Spirit Ltd | Wholesale & retail | 2025 |
| Shamil Lulu Properties Ltd | Real estate | 2011 |
| Shams-Ul-Qamer Ltd | Wholesale & retail | 2022 |
| Shanaya Ltd | Health & social care | 2014 |
| Shandon Smiles Limited | Health & social care | 2024 |
| Shanghaitime Ltd | Hospitality | 2025 |
| Shanick Engineering Limited | Manufacturing | 1972 |
| Shanon the Collective Limited | Other services | 2020 |
| Shape Aesthetic Clinic Ltd | Health & social care | 2023 |
| Shapes of Nail Ltd | Other services | 2024 |
| Shapins Group Ltd | Financial services | 2012 |
| Sharan Suthar Limited | Health & social care | 2017 |
| Shardi Shai Limited | Hospitality | 2019 |
| Shared Beauty Secrets Limited | Wholesale & retail | 2009 |
| Shared Dreams Limited | Extraterritorial | 2009 |
| Sharfe Kapital Investition Limited | Financial services | 2018 |
| Sharman Civil Solutions Ltd | Construction | 2018 |
| Sharon Rebbett Book-Keeping Ltd | Professional & scientific | 2002 |
| Sharp Vending Solutions Limited | Wholesale & retail | 2025 |
| Sharp&Shape Barbers Limited | Other services | 2024 |
| Sharpsquares Ltd | Professional & scientific | 2014 |
| Shawn Buckingham Ltd | Information & communication | 2024 |
| SHD Sussex LLP | | 2017 |
| She's Gone MAD Limited | Administrative & support | 2024 |
| Shedon Limited | Health & social care | 2013 |
| Sheelen Patel Ltd | Health & social care | 2023 |
| Sheengate Media Corp Ltd | Professional & scientific | 2021 |
| Sheldon Hotel (Holdings) Limited | Hospitality | 2010 |
| Sheldon Hotel Limited | Hospitality | 2022 |
| Shell Shock Media CIC | Arts & recreation | 2017 |
| Shelleys Estates Limited | Real estate | 2013 |
| Shelton Properties Limited | Real estate | 2003 |
| Shemak Ltd | Real estate | 2017 |
| Shembesh and Belhaj Limited | Health & social care | 2014 |
| Shemsije Construction Limited | Construction | 2025 |
| Shepherds Love Limited | Professional & scientific | 2023 |
| Sherwood Court (Eastbourne) Limited | Households | 2014 |
| Shieldpiercer Limited | Financial services | 2022 |
| Shifty Events Limited | Information & communication | 2025 |
| Shillan Ltd | Professional & scientific | 2023 |
| Shine Private Ltd | Wholesale & retail | 2023 |
| Shinefulness Limited | Other services | 2019 |
| Shinfield Green Limited | Health & social care | 2018 |
| Shipping Direct UK Limited | Transport & logistics | 2018 |
| Shirebrook Dental Care Limited | Health & social care | 2014 |