| Safety Advisors Sussex Limited | Professional & scientific | 2023 |
| Saffron Caravane Limited | Wholesale & retail | 2025 |
| Saffrons Gate Limited | Households | 1995 |
| Saffrons Mead Management Company Limited | Households | 1997 |
| Safira Brasil UK Limited | Arts & recreation | 2022 |
| Sage & Stone Wellness Ltd | Other services | 2025 |
| Sage Botanicals Ltd | Wholesale & retail | 2024 |
| SAI Assets Ltd | Real estate | 2018 |
| Saintablett Ltd | Wholesale & retail | 2024 |
| Saion Limited | Information & communication | 2017 |
| Sakura LCY Limited | Manufacturing | 2019 |
| Salient Sea Ltd | Manufacturing | 2025 |
| Salon Spencer Ltd | Other services | 2018 |
| Saltmarsh Farmhouse Ltd | Administrative & support | 2008 |
| Saltmarsh Farms Limited | Agriculture & fishing | 2023 |
| Salty Bottom Ltd | Wholesale & retail | 2020 |
| Salvi Consulting Limited | Professional & scientific | 2017 |
| SAM & YIP Limited | Hospitality | 2012 |
| Samaritans Retail (Eastbourne) Limited | Wholesale & retail | 2006 |
| Sambai Advisory Ltd | Professional & scientific | 2026 |
| Sami Alam Limited | Health & social care | 2009 |
| Samms Construction Limited | Construction | 2025 |
| Samtok Limited | Construction | 2024 |
| Samuel Plumbing & Heating Services Ltd | Construction | 2018 |
| Sanaa Foods UK Ltd | Hospitality | 2019 |
| Sanamah Ltd | Wholesale & retail | 2025 |
| Sanara Wellness Limited | Arts & recreation | 2025 |
| Sand Global Investments Limited | Real estate | 2011 |
| Sandamac Limited | Real estate | 2019 |
| Sandford Homes & Developments Limited | Construction | 2019 |
| Sanecommunications Limited | Other services | 2008 |
| Sanoot Limited | Real estate | 2021 |
| Sanshaw Court Eastbourne Limited | Households | 1989 |
| Santana Auto Services Ltd | Wholesale & retail | 2026 |
| Santoscompany Ltd | Wholesale & retail | 2023 |
| SAP Health Limited | Health & social care | 2024 |
| Sapcom Jointing Limited | Construction | 2025 |
| Sapphire Dental Ltd | Health & social care | 2020 |
| Sara Court Residents Limited | Households | 2003 |
| Saragan Games Limited | Information & communication | 2025 |
| Sarah B Productions Ltd | Professional & scientific | 2022 |
| Sarah Barron Limited | Professional & scientific | 2009 |
| Sarah Elizabeth Best Ltd | Arts & recreation | 2024 |
| Sarah James Consulting Ltd | Professional & scientific | 2022 |
| Sarah Jelly Limited | Professional & scientific | 2015 |
| Sarah Warren Art Limited | Arts & recreation | 2003 |
| Sarahmed Limited | Health & social care | 2010 |
| Sargant Blood Services Clinic Ltd | Health & social care | 2026 |
| Sargeant Hall Limited | Wholesale & retail | 2009 |
| Sarvestani Limited | Health & social care | 2013 |
| SAS Electrics Limited | Construction | 2012 |
| Sashpro Limited | Construction | 2007 |
| SAT Developments Limited | Construction | 2019 |
| Sauce Grande Properties Ltd | Financial services | 2025 |
| Saunders & Kinder Limited | Hospitality | 2024 |
| Savan Shah Dental Limited | Health & social care | 2020 |
| Savitaamrutam Ltd | Wholesale & retail | 2022 |
| Sawyer Trading Limited | Administrative & support | 2008 |
| Saxon Design Services Limited | Administrative & support | 2016 |
| SAY Cheers MK02 Ltd | Wholesale & retail | 2018 |
| SAY Dental Ltd | Financial services | 2018 |
| Saygee Estate Holdings Limited | Financial services | 1962 |
| SB & ANA Ltd | Health & social care | 2013 |
| SBE Property Developments Ltd | Real estate | 2023 |
| SBP Events Limited | Administrative & support | 2016 |
| SBP Health Magnetic Products Ltd | Wholesale & retail | 2025 |
| SBR a Ltd | Administrative & support | 2026 |
| SBR Allsorts Ltd | Wholesale & retail | 2025 |
| SC Engineering Solutions Limited | Professional & scientific | 2022 |
| Scandic Health Limited | Health & social care | 2016 |
| Scantec Automotive Limited | Administrative & support | 2016 |
| School of Authenticity CIC | Education | 2025 |
| Scolls Property Ltd | Real estate | 2020 |
| Scorch Comics Ltd | Wholesale & retail | 2015 |
| Scott Kemlo Ltd | Manufacturing | 2019 |
| Scott Owen Lettings Limited | Real estate | 2013 |
| Scotts News Agent Ltd | Wholesale & retail | 2025 |
| Scrap Metal Solutions Limited | Water & waste | 2026 |
| Scriptworks Productions Ltd. | Information & communication | 2020 |
| Scuffs Mobile Body Repairs Limited | Wholesale & retail | 2016 |
| SD32 Limited | Health & social care | 2025 |
| SDC Psychiatry Ltd | Health & social care | 2014 |
| Sdhc Developments Ltd | Administrative & support | 2017 |
| SDJ Property's Ltd | Real estate | 2023 |
| Sea Training Sussex Ltd | Other services | 2010 |
| Seabreeze Cleaning Ltd | Administrative & support | 2013 |
| Seacall Ltd. | Wholesale & retail | 1998 |
| Seafood & More Limited | Wholesale & retail | 2022 |
| Seaford Business Assistance Limited | Professional & scientific | 2009 |
| Seaford Family Care Limited | Health & social care | 2026 |
| Seaford Launderette LLP | | 2021 |
| Seahaven Estate Ltd | Professional & scientific | 2026 |
| Seahill Ltd | Hospitality | 2025 |
| Sean Kirk Fencing Limited | Administrative & support | 2011 |
| Sean Lenihan Brickworks Limited | Construction | 2009 |
| Seashell Hotel Ltd | Hospitality | 2026 |
| Seaside Dental Practice Limited | Health & social care | 2008 |
| Seaside Homes Limited | Real estate | 2017 |
| Seaside Management 1 Limited | Households | 2014 |
| Seaside Sports Ltd | Arts & recreation | 2023 |